GetPDFServlet_filetype=pdf&id=JVTAD6000022000004001652000001
链接转pdf java
在Java中将链接转换为PDF文件，通常需要使用一些第三方库，如Jsoup 用于抓取网页内容，然后使用iText或PDFBox等库将HTML内容转换为PDF 格式。
以下是一个基本的步骤示例：
1. 添加依赖项：
对于Jsoup：在你的Maven或Gradle构建文件中添加Jsoup依赖。
对于iText或PDFBox：添加相应的PDF生成库依赖。
2. 使用Jsoup抓取网页内容：
java代码：
3. 将HTML内容转换为PDF：
如果使用iText：
java代码：
如果使用PDFBox：
java代码：
注意：上述PDFBox示例中并没有直接将HTML转换为PDF，因为PDFBox 本身并不直接支持HTML到PDF的转换。
你可能需要结合使用Flying Saucer 或Apache FOP等其他库来实现这一功能。
请根据你的具体需求和环境选择合适的库和方法进行链接转PDF的操作。
同时，由于网络抓取和PDF生成可能会涉及到版权和许可问题，确保你在进行此类操作时遵守相关法律法规和网站的使用条款。
pdfjs的getdocument方法
pdfjs的getdocument方法
PDFJS.getDocument是一个用于从PDF文件获取文档对象的方法，它属于PDF.js库。
PDF.js是一个由Mozilla开发的JavaScript库，用于在Web浏览器中查看PDF文件。
使用PDFJS.getDocument方法，你可以加载一个PDF文件并将其转换为可以在Web页面上查看和交互的对象。
这个方法接受一个URL作为参数，该URL指向要加载的PDF文件。
以下是PDFJS.getDocument方法的基本用法：
var pdfDoc = PDFJS.getDocument('url/to/pdf');
在这个例子中，'url/to/pdf'是PDF文件的URL。
这个方法将返回一个Promise对象，表示正在异步加载PDF文档。
当PDF文档成功加载后，可以使用返回的Promise对象的.then方法处理加载完成的文档对象。
注意，你需要先加载PDF.js库，才能使用PDFJS.getDocument方法。
你可以通过CDN链接或本地文件来加载PDF.js库。
最后总结一下，PDFJS.getDocument方法是用于从URL加载PDF文件并将其转换为可在Web页面上查看和交互的文档对象的方法。
这个方法返回一个Promise对象，表示正在异步加载PDF文档。
当文档加载完成后，可以使用.then方法处理加载完成的文档对象。
java pdf读取的几种方法
在Java中，有几种主要的方法可以用来读取PDF文件：1.Apache PDFBox: Apache PDFBox是一个开源的Java库，用于处理PDF文档。
你可以使用它来读取、创建、修改PDF文件等。
它支持各种功能，例如提取文本、图像，添加水印，加密和解密PDF文件等。
2.iText: iText是一个用于处理PDF文件的商业库。
它提供了许多功能，如创建PDF文件、添加文本、图像、表格，以及读取、修改和加密PDF文件等。
3.jPDFBox: jPDFBox是另一个Java库，用于处理PDF文件。
它的功能包括读取PDF文件的内容，提取图像，添加书签等。
4.Batik: Apache Batik是一个用于处理PDF文件的工具集，它是ApacheXML Graphics Project的一部分。
除了处理PDF文件，Batik还支持SVG 文件。
5.Poppler: Poppler是一个用于渲染PDF文档的库。
Poppler基于Qt和Glib，并且是免费的。
Poppler可以用于显示PDF文件，也可以用于提取文本和图像。
Poppler通常与Evince一起使用，Evince是一个开源的PDF 阅读器。
6.PDFBox-Android: PDFBox-Android是Apache PDFBox的一个分支，专门为Android平台设计。
它支持大部分的PDFBox功能，并且针对Android进行了优化。
以上这些库都有自己的优缺点，你可以根据你的具体需求来选择适合你的库。
例如，如果你需要加密和解密PDF文件，那么iText可能更适合你。
如果你只需要读取PDF文件的内容，那么Poppler可能是一个更好的选择。
Servlet习题
username:<input type=”text” name = “userName” id=”myName” value=”yourName”> </form>当表单提交时，下列选项中，能够获取到文本框中值的是 A、request.getAttribute(“userName”); B、request.getParameter(“myName”); C、request.getParameter(“userName”); D、request.getAttribute(“myName”);
B、<servlet> <servlet-name> syxy.Student </servlet-name> <servlet-value> /start/*</servlet-class> </servlet>
C、<servlet> <servlet-name>student</servlet-name> <servletvalue>syxy.Student</servlet-class> </servlet> <servlet-mapping> <servletname>student</servlet-name> <url-pattern>/start/*</url-pattern> </servlet-mapping>
15. 下列关于<servlet-mapping>作用的说法中，正确的是( )
servlet输出PDF到请求端
servlet输出PDF到请求端⼤部分时候会从HttpServletResponse取得PrintWriter实例，使⽤println()⽅法对浏览器进⾏字符输出，但是有时候需要对浏览器进⾏字节输出，这就需要⽤到getOutputStream()⽅法来取得ServletOutputStream实例。
它是OutputStream的⼦类。
下⾯⽤例⼦说明，浏览器请求返回pdf类型的⽂件。
package com.sunyongxing.servlet;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/pdf.do")public class PdfServlet extends HttpServlet {private static final long serialVersionUID = 1L;/*** @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse* response)*/protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {String password = request.getParameter("password");if ("123456".equals(password)) {response.setContentType("application/pdf");InputStream in = getServletContext().getResourceAsStream("/WEB-INF/1.pdf");OutputStream out = response.getOutputStream();byte[] b = new byte[1024];int length = -1;while ((length = in.read(b)) != -1) {System.out.println(length);out.write(b, 0, length);}in.close();out.close();}}}当请求pdf.do的servlet，密码符合时就会返回pdf⽂件，红⾊标记的第⼀⾏是设置返回的类型，这⾥设置的是pdf类型，当浏览器不知道是什么类型时。
HttpServletRequest常用方法
public String getAuthType();返回这个请求的身份验证模式。
2、getCookiespublic Cookie[] getCookies();返回一个数组，该数组包含这个请求中当前的所有cookie。
如果这个请求中没有cookie，返回一个空数组。
3、getDateHeaderpublic long getDateHeader(String name);返回指定的请求头域的值，这个值被转换成一个反映自1970-1-1日（GMT）以来的精确到毫秒的长整数。
如果头域不能转换，抛出一个IllegalArgumentException。
如果这个请求头域不存在，这个方法返回-1。
4、getHeaderpublic String getHeader(String name);返回一个请求头域的值。
（译者注：与上一个方法不同的是，该方法返回一个字符串）如果这个请求头域不存在，这个方法返回-15、getHeaderNamespublic Enumeration getHeaderNames();该方法返回一个String对象的列表，该列表反映请求的所有头域名。
有的引擎可能不允许通过这种方法访问头域，在这种情况下，这个方法返回一个空的列表。
public int getIntHeader(String name);返回指定的请求头域的值，这个值被转换成一个整数。
如果头域不能转换，抛出一个IllegalArgumentException。
如果这个请求头域不存在，这个方法返回-1。
7、getMethodpublic String getMethod();返回这个请求使用的HTTP方法（例如：GET、POST、PUT）8、getPathInfopublic String getPathInfo();这个方法返回在这个请求的URL的Servlet路径之后的请求URL的额外的路径信息。
JAVAWEB 程序设计 习题参考答案(第1 6章)
从表单中获取多个值用 getParameterValues,求数组的长度为 length。
7、用户使用 POST 方式提交的数据中存在汉字（使用 GBK 字符集） ，在 Servlet 中需要使用 下面____个语句处理。 A、request.setCharcterEncoding(“GBK”); B、request.setContentType(“text/html;charset=GBK”); C、reponse.setCharcterEncoding(“GBK”); D、response.setContentType(“text/html;charset=GBK”); 参考答案：A 其中 D 是设置响应的方式的，A 是设置请求的方法。其他两个是错误的。选择：A 8、简述 Servlet 的生命周期。Servlet 在第一次和第二次被访问时，生命周期方法的执行有何 区别。 参考答案： 1、 在 Servlet 容器刚被启动时加载，也可以在容器收到客户请求服务时加载 <servlet> <load-on-startup>1</load-on-startup> </servlet> 标签<load-on-startup>配置该 Servlet 的加载方式， 可选值为 0 和 1， 如果配置为 1.Tomcat 会在启动时候加载该 Servlet，否则，Tomcat 会在有人第一次请求该 Servlet 时才加载该 Servlet 2、 加载成功后，Servlet 容器便可以创建一个 Servlet 实例。Servlet 加载并实例化后，在处 理客户端请求前，容器必须通过调用它的 init 方法进行初始化 3、 实例创建好后，就要对其初始化。Servlet 的 init()方法的主要任务就是完成初始化工作。 该方法由 Servlet 容器调用完成。对于每一个 Servlet 实例，该方法只允许被调用一次。 4、 利用 service 处理请求 在 Servlet 被成功初始化后容器就可以使用它去处理客户端发来的请求了。在使用 HTTP 协议发送请求时，容器必须提供代表请求和回应的 HttpServletRequest 对象和 HttpServlerRespons 5、利用 destroy()方法终止服务 在 Servlet 执行完毕或是在处理请求过程中出现 UnavailiableException 异常，需要移除 Servlet，在移除之前，Servlet 会调用 destroy()方法让 Servlet 自动释放占用的资源。 第一次访问时会执行 init()方法，第二次访问不会执行 init()方法。 9、简述转发和重定向跳转方式的区别，在 Servlet 中分别使用什么方法实现？ 重定向跳转方式的区别：转发和重定向都可以使浏览器获得另外一个 URL 所指向的资 源，区别是转发共享同一个请求对象，而重定向不共享同一个请求对象。 在 Servlet 中分别使用什么方法实现？在 Servlet 中转发使用 RequestDespacher 接口的 forward()方法实现。重定向由 HttpServletResponse 接口的 sendRedirect（）方法实现。
GetPDFServlet
Blue luminescence from Si؉-implanted SiO2films thermally grown on crystalline siliconLiang-Sheng Liao,Xi-Mao Bao,Xiang-Qin Zheng,Ning-Sheng Li,and Nai-Ben MinDepartment of Physics and National Laboratory of Solid State Microstructures,Nanjing University,Nanjing,Jiangsu210093,People’s Republic of China͑Received28July1995;accepted for publication14November1995͒Si ions were implanted into thermally grown SiO2films on crystalline Si at an energy of120keVand with a dose of2ϫ1016cmϪ2.Under an ultraviolet excitation ofϳ5.0eV,the implantedfilmsexhibit blue luminescence with a peak ofϳ2.7eV at room temperature.The blue emission is causedby oxygen vacancies in thefilms.©1996American Institute of Physics.͓S0003-6951͑96͒03904-6͔Semiconductor light-emitting materials are very impor-tant to visible displaying devices and to optoelectronics.In thefield of displaying devices,red-and green-light-emitting diodes͑LEDs͒are well developed among the three primary colors.Recently,because of the breakthrough in the research of luminescent GaN,1intense blue LEDs are also put to wide use,and a bright semiconductor full-color display then comes true.In thefield of optoelectronics,because Si is a nonfungible semiconductor microelectronics material,people have long been looking forward to the realization of Si-based integrated optoelectronics by taking advantage of Si planar technique.The discovery of luminescent porous silicon͑PS͒2 has greatly stimulated the interest in the optoelectronics and much progress has been achieved since then.PS can easily exhibit intense photoluminescence͑PL͒from a red to green band under different preparation conditions,but it is difficult to exhibit intense and stable blue luminescence.3,4Because the blue color is also crucial to the Si-based full-color dis-play,some other methods are attempted to achieve blue emission.5–9SiO2films are extensively used in silicon devices and integrated circuits as passivation layers and electrical insula-tion layers.Their optical properties have been investigated. DiMaria et al.10studied the electroluminescence͑EL͒from Si-rich SiO2films prepared by CVD on crystalline Si.Re-cently,SiO2films,as possible Si-based light-emitting mate-rials are attracting new attention.Shimizu-Iwayama et al.11 have carried out studies using Siϩimplantation with MeV energy and a heavy dose(1–4ϫ1017ions/cm2)into ther-mal SiO2films and have shown two PL bands,2.0eV band and1.7eV one,under a488nm excitation.From the view-point of the Si-based full-color display,it is interesting to examine the light emission of the implanted SiO2films in a blue wavelength band.It is known that some bulk SiO2͑such as high-purity silica glasses͒can exhibit a2.7eV band at low temperature, but the2.7eV band was not seen in the thermal dioxide.12 However,we observed a fairly stable blue emission͑ϳ2.7 eV band͒from Siϩ-implanted SiO2films thermally grown on Si substrate under an ultraviolet excitation ofϳ5.0eV at room temperature.We report our observation in this letter.The starting materials are5⍀cm,͗100͘,p-type Si wa-fers.SiO2films were grown on the wafers by thermal oxida-tion in a quartz tubeflushed with wet O2gas͑500ml/min͒at 1100°C for20min.The oxide thickness was about360nm.Siϩwas implanted into the thermal SiO2films at an energyof120keV and with a dose of2ϫ1016cmϪ2.During im-plantation,the substrate was kept at room temperature.Theas-implantedfilms were annealed in N2ambient for30min,at300,400,500,600,700,800,900,and1000°C,respec-tively.The purity of N2gas used for annealing isϾ99%.ThePL spectra and the photoluminescence excitation͑PLE͒spec-tra were taken at room temperature using a Hitachi F-3010fluorescence photospectrometer with correction for instru-mental wavelength dependencies.The light source of thespectrometer is a150W xenon lamp.The electron spin reso-nance͑ESR͒signals were measured at room temperature us-ing a Bruker ER-200D X-band spectrometer,operating at alow microwave power of6.4mW to avoid satuation.A stan-dard sample was used to calibrate the spin density.Figure1shows the PL and PLE spectra of the samples.Curve a is a PL spectrum of the as-implanted SiO2film un-derϳ5.0eV excitation(exϭ250nm͒.Its PL peak is at470 nm͑2.64eV͒with the full width at half-maximum͑FWHM͒of86nm͑0.49eV͒.This curve is unsymmetrical.In fact,itFIG. 1.The PL and PLE spectra of the SiO2films.͑a͒PL of Siϩ-implantedfilm,͑b͒PLE of Siϩ-implantedfilm,and͑c͒PL of nonim-plantedfilm.The dotted curves are the subbands of curve a,and are drawn according to curve-fitting method.The vertical dashed line indicates the PL measuring limit by a310nm cutofffilter.consists of three subbands,ϳ370nm ͑3.4eV ͒band,ϳ467nm ͑2.65eV ͒band,and ϳ520nm ͑2.4eV ͒one,which are shown as dotted lines.These band fit the PL curve very well.Curve b is a PLE spectrum monitored at the emission wave-length (em )of 470nm.Its peak is at 250nm with the FWHM of 35nm ͑0.69eV ͒.For comparison,a PL spectrum of a nonimplanted SiO 2film under the 5.0eV excitation is shown as curve c,which also has a weak band at ϳ370nm.The vertical dashed line indicates the PL measuring limit by a 310nm cutoff filter.Figure 2shows the PL characteristic of the implanted SiO 2films via annealing temperature.The PL peak intensity first increases as the annealing temperatures increases,and reaches its maximum at 500–600°C.Then,the intensity de-creases rapidly with increasing annealing temperature,and it is nearly disappeared at 1000°C ͑shown as curve a ͒.The difference of the PL peak intensity is within 20%in the range of 300–650°C.Moreover,the PL peak wavelength blue-shifts slow as the annealing temperature increases,and the peak wavelength of the 1000°C -annealed sample is about 20nm shorter than that of the as-implanted one ͑shown as curve b ͒.During thermal annealing,not only the PL peak intensity and PL peak wavelength,but also the FWHM of the PL peak,are changed.The FWHM of the PL peak for the as-implanted sample is about 86nm.It first decreases as the annealing temperature increases,and reaches its minimum ͑80nm ͒at 500–600°C.When the annealing temperature is higher than 600°C,the FWHM increases with the decrement of PL peak intensity.When the annealing temperature is at 1000°C,the FWHM of the PL spectrum is about 170nm.Shown in Fig.3are the ESR signals of the SiO 2films.Upon implantation,the film shows an intense signal as curve a in which spin density is about 1.8ϫ1015/cm 2and the zero-crossing g value is 2.0000.This means that some kind of paramagnetic defects are induced in the film by the Si ϩim-plantation.The defects should be the E ’defect centers (O 3ϵSi •͒.13The defect density decreases with thermal an-nealing,and is almost disappeared at 600°C ͑curve e ͒.Forcomparison,a nonimplanted SiO 2film was also measured,and its ESR signal is shown as curve g.We successfully observed the blue emission from Si ϩ-implanted thermal SiO 2films,but Shimizu-Iwayama et al.11did not report this blue band.It is obvious that the blue emission requires ultraviolet excitation,thus,it cannot be observed when a visible range excitation is used.In Si ϩ-implanted thermal SiO 2films both nanocrystal-line Si and defects may induce PL.11If the PL is from nano-crystalline Si,its peak wavelength will redshift as the size of nanocrystalline Si increases according to the quantum size effect.On the other hand,if the PL is from defects,its inten-sity will decrease as the defect densities diminishes.As mentioned above,our as-implanted SiO 2films were annealed at 300–1000°C,and the PL peak wavelength blue-shifts with increasing temperature ͑Fig.2͒.Moreover,instead of Si ϩimplantation,Ar ϩ-implanted thermal SiO 2films also have the same 2.7eV PL peak ͑with weaker intensity ͒.These results indicate that the blue emission in the Si ϩ-implanted SiO 2films is not directly related to nanocrystalline Si.There is a well known optical absorption band,B 2band,with the absorption energy of ϳ5.0eV in high-purity silica glasses.14,15The B 2band is induced by oxygen vacancies (O 3ϵSi–Si ϵO 3).14Under the 5.0eV excitation,the oxygen vacancies may exhibit a ϳ2.7eV PL feature.14,15But no 2.7eV PL peak was observed in the nonimplanted thermal SiO 2films under the excitation energy at/above 5.0eV ͑shown as curve c in Fig.1͒.Upon Si ϩimplantation,theFIG.2.Effect of thermal annealing ͑a ͒on PL peak intensity,and ͑b ͒on PL peak wavelength.The annealing time is 30min.The solid lines are the aid to theeye.FIG.3.ESR signals of the SiO 2films.͑a ͒as-implanted sample.͑b ͒–͑f ͒samples annealed at 300,400,500,600,and 1000°C,respectively,and ͑g ͒nonimplanted film.films become nonstoichiometric with excess Si.As a result,oxygen vacancies in thefilms are induced.Similar to thehigh-purity silica glasses,the as-implanted SiO2films exhibitthe PL peaked at2.7eV under the5.0eV excitation as well.In our experiments,the thickness͑d͒of thefilms is about360nm,the absorption coefficient͑␣͒is less than 104/cm,16and then␣dӶ1.In this case,the PLE can reflect the same transition process as light absorption in thefilms.17Therefore,the PLE peak of250nm is one of the opticalabsorption bands,B2band,which is oxygen vacancy related.Consequently,it is reasonable to assume that the blue emis-sion from Siϩ-implanted SiO2films is induced by the oxy-gen vacancies.The relatively broad PL peak consists of three subbandswhich have different thermal annealing behaviors.Althoughthe intensity of each subbandfirst increases and then de-creases with increasing temperature,it begins to decrease atdifferent temperature.Theϳ520nm band begins to decreaseat300°C,theϳ467nm band at600°C,and the370nmband at700°C.As a result,the PL peak wavelength blue-shifts with increasing temperature.With the same reason,when the intensity ratio of467nm band to520nm bandincreases,the FWHM of the PL peak decreases͑in a tem-perature range of20–500°C͒;when the ratio of370nmband to467nm band increases,the FWHM of the PL peakincreases͑at the temperature higher than600°C͒.Therefore,there is a minimum FWHM value corresponding to someannealing temperature͑at500–600°C͒.As shown in Fig.1,the370nm weak band appears both in the Siϩ-implantedand in the nonimplanted samples.This band may relate tosome intrinsic defects,and the520nm band may relate tosome other kinds of defects in thefilms.Further investiga-tion is underway,and we will discuss these bands elsewhere.Generally,two kinds of defects,diamagnetic defects andparamagnetic defects,are produced by Siϩimplantation.TheB2band(O3ϵSi–SiϵO3͒is a diamagnetic defect,which is also a radiative recombination center.14According to ESRmeasurement,the paramagnetic defect in thefilms is somekind of E’centers(O3ϵSi•͒,which is a Si dangling bond,18 and is a nonradiative recombination center.19The two kinds of defects will affect the blue PL intensity of thefilms oppo-sitely.Furthermore,both the defects have different annealing behavior which will determine the annealing characteristic of the PL in thefilms.Curve a in Fig.2illustrated that up to 600°C the relative proportion of radiative recombination in-creases while that of nonradiative recombination decreases. This may be the result of the diminution of the nonradiative defect density due to thermal annealing.Figure3has con-firmed that the Si dangling bonds are reconstructed and the density of E’centers decreases during annealing.At tempera-ture above600°C,the E’centers almost disappear.There-fore,the increase of the blue peak intensity is consistent with the decrease of E’center density when annealing temperature is lower than600°C.However,when annealing temperature is higher than600°C,the blue PL intensity decreases rap-idly,which may be due to the resolution of the oxygen va-cancies at high temperatures.The thermal annealing at about 600°C can increase the blue PL of the implanted SiO2films and make the emission more stable.In summary,Siϩ-implanted thermal SiO2films on crys-talline Si can exhibit blue PL with a peak at2.7eV under the 5.0eV excitation.The PL intensity reaches its maximum when annealed in N2at500–600°C for30min,and it is quite stable as well.The blue emission is caused by oxygen vacancies induced by Siϩimplantation in thefilms.The preparation of the implanted thermal SiO2films are com-pletely compatible with the current Si planar technique,and is favorable to the realization of integrated optoelectronics.The authors gratefully thank Zhi-Xin Lin,Lian-Zhu Li, and Yun-Xia Sui for their technical assistance,and gratefully thank the helpful discussion from Professor Xiang-Na Liu, Professor Qing-Chen Zeng,and Dr.Feng Yan.This work is supported by the National Natural Science Foundation of China.Partial support from the National Joint Laboratory of Material Modification by Photon-,Electron-,and Ion-Beam, Dalian Polytechnic University,China is acknowledged as well.1S.Nakamura,T.Mukai,and M.Senoh,Appl.Phys.Lett.64,1687͑1994͒. 2L.T.Canham,Appl.Phys.Lett.57,1046͑1990͒.3X.Wang,G.Shi,F.L.Zhang,H.J.Chen,W.Wang,P.H.Hao,and X.Y. Hou,Appl.Phys.Lett.63,2363͑1993͒.4C.I.Harris,M.Syva¨ja¨rvi,J.P.Bergman,O.Kordina,A.Henry,B.Mon-emar,and E.Janze´n,Appl.Phys.Lett.65,2451͑1994͒.5H.Morisaki,H.Hashimoto,F.W.Ping,H.Nozawa,and H.Ono,J.Appl. Phys.74,2977͑1993͒.6D.Ru¨ter,T.Kunze,and W.Bauhofer,Appl.Phys.Lett.64,3006͑1994͒. 7L.S.Liao,X.M.Bao,Z.F.Yang,and N.B.Min,Appl.Phys.Lett.66, 2382͑1995͒.8X.N.Liu,X.W.Wu,X.M.Bao,and Y.L.He,Appl.Phys.Lett.64,220͑1994͒.9S.Tong,X.N.Liu,and X.M.Bao,Appl.Phys.Lett.66,469͑1995͒. 10D.J.DiMaria,J.R.Kertley,E.J.Pakulis,D.W.Dong,T.S.Kuan,F.L. Pesavento,T.N.Theis,J.A.Cutro,and S.D.Brorson,J.Appl.Phys.56, 401͑1984͒.11T.Shimizu-Iwayama,S.Nakao,and K.Saitoh,Appl.Phys.Lett.65,1814͑1994͒.12J.H.Stathis and M.A.Kastner,Phys.Rev.B35,2972͑1987͒.13J.F.Conley Jr.,P.M.Lenahan,H.L.Evans,R.K.Lowry,and T.J. Morthorst,J.Appl.Phys.76,2872͑1994͒.14H.Nishikawa,T.Shiroyama,R.Nakamura,Y.Ohki,K.Nagasawa,and Y. Hama,Phys.Rev.B45,586͑1992͒.15R.Tohmon,Y.Shimogaichi,H.Mizuno,Y.Ohki,K.Nagasawa,and Y. Hama,Phys.Rev.Lett.62,1388͑1989͒.16G.W.Arnold,IEEE Trans.Nucl.Sci.NS-20,220͑1973͒.17L.Wang,M.T.Wilson,and N.M.Haegel,Appl.Phys.Lett.62,1113͑1993͒.18P.M.Lenahan and P.V.Dressendorfer,IEEE Trans.Nucl.Sci.NS-29, 1459͑1982͒.19N.Ookubo,H.Ono,Y.Ochiai,Y.Mochizuki,and S.Matsui,Appl.Phys. Lett.61,940͑1992͒.。
使用pdf.js+jsp预览pdf
使⽤pdf.js+jsp预览pdf参考⼀：准备⼯作1.在pdf.js 官⽹下载到本地2.把下载的压缩包pdfjs-2.2.228-dist.zip解压到pdfjs⽂件夹下，包含两个⽂件夹：build和web3.把pdfjs⽂件夹放⼊你的项⽬ webapp⽬录下 (我的项⽬名称是web-demo)（例如）因为webapp⽬录下的⽂件可以通过浏览器路径访问⼀：先看下pdf.js + jsp 实现预览pdf的效果运⾏项⽬在浏览器输⼊就可以先看⼀下效果了。
4.pdf.js 渲染pdf 就是viewer.html⽂件实现的，它默认渲染的是和viewer.html⽂件同⽬录下的compressed.tracemonkey-pldi-09.pdf设置加载这个⽂件的地⽅是：viewer.html⽂件同⽬录的viewer.js⽂件⾥设置的，修改这个属性的值就能够预览不同的⽂件，中英⽂的pdf⽂件都能成功预览。
defaultUrl: {value: 'compressed.tracemonkey-pldi-09.pdf',kind: OptionKind.VIEWER}⼆：实战从后端读取⽂件前端页⾯显⽰1.添加依赖包<dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.6</version></dependency><!-- jsp ⽂件 taglib依赖 --><dependency><groupId>taglibs</groupId><artifactId>standard</artifactId><version>1.1.2</version></dependency>2.新建viewPdf.jsp⽂件根据viewer.html⽂件渲染pdf⽂件，⽂件来源是从后端读取的，file后的参数后后端⽅法的mapping,这⾥要注意在file 后的路径上加上项⽬名<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%><%@taglib prefix="c" uri="/jsp/jstl/core"%><html><body><h2>this is viewPdf page</h2><iframesrc="<c:url value="pdfjs/web/viewer.html" />?file=/web-demo/getPdfFile" width="100%" height="800"></iframe></body></html>3.后端controller实现import java.io.File;import java.io.FileInputStream;import java.io.OutputStream;import javax.servlet.http.HttpServletResponse;import mons.io.IOUtils;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;/*** 在线预览pdf*/@Controllerpublic class ViewPDFController {@RequestMapping("/viewPdf")public String viewPDF() {return "viewPdf";}@RequestMapping("/getPdfFile")public void getPDF(HttpServletResponse response) {try {File file = new File("G:/test.pdf");FileInputStream fileInputStream = new FileInputStream(file);response.setHeader("Content-Disposition", "attachment;fileName=test.pdf");response.setContentType("multipart/form-data");OutputStream outputStream = response.getOutputStream();IOUtils.write(IOUtils.toByteArray(fileInputStream), outputStream);} catch (Exception e) {e.printStackTrace();}}}4.运⾏项⽬，在浏览器输⼊就可以看到效果了页⾯会显⽰G盘的test.pdf⽂件。
java生成复杂pdf的方法
java生成复杂pdf的方法摘要：1.Java 生成复杂PDF 的方法1.1.Java 的优势1.2.生成复杂PDF 的方法1.2.1.使用iText 库1.2.2.使用Apache PDFBox 库1.2.3.使用Java 内置的PDF 支持1.3.选择合适的库1.4.总结正文：Java 作为一种广泛应用的编程语言，具有跨平台、可移植性强等优势。
在生成复杂PDF 方面，Java 同样具有很好的表现。
本文将介绍几种Java 生成复杂PDF 的方法。
首先，Java 的优势在于其跨平台性，这意味着在编写代码时，可以忽略底层操作系统和硬件的差异，从而更专注于业务逻辑。
此外，Java 有着丰富的开源库，可以帮助开发者轻松实现各种功能。
在生成复杂PDF 方面，Java 有多种方法可供选择。
其中，使用iText 库、Apache PDFBox 库以及Java 内置的PDF 支持是最常见的几种方式。
iText 库是一个功能强大的Java PDF 库，可以轻松地创建、编辑和处理PDF 文件。
它提供了丰富的API，支持各种PDF 对象的创建和操作。
使用iText 库，可以方便地实现复杂PDF 的生成，例如添加图片、表格、超链接等。
同时，iText 库还支持将PDF 文件转换为其他格式，如HTML、XML 等。
Apache PDFBox 库是另一个常用的Java PDF 库，它提供了一组工具，用于处理PDF 文档。
与iText 库相比，PDFBox 库更注重底层操作，可以实现对PDF 文件的无缝解析。
通过PDFBox 库，可以提取PDF 文件中的文本、图片等元素，并对其进行操作。
这使得Apache PDFBox 库在处理复杂PDF 时具有较高的灵活性。
此外，Java 内置的PDF 支持也是一个值得关注的领域。
随着Java 7 的发布，Java 引入了PDF 支持，使得开发者可以直接在Java 代码中处理PDF 文件。
Servlet习题
11. 下面选项中, 用于根据指定名称获取 ServletContext 的域属性值的方法是( )
A、String getAttibute(String name) B、Object getAttibute(String name) C、String getAttibute(Object name) D、Object getAttibute(Object name)
D、<servlet> <servlet-name>syxy.Student </servlet-name> <servlet-value>student </servlet-class> </servlet> <servlet-mapping> <servlet-name> syxy.Student </servletname> <url-pattern>/start/*</url-pattern> </servlet-mapping>
访问servlet时web服务器直接返回servlet的源码d后者需要在webxml文件中配置url路径判断题servlet是一个服务器上运行处理请求信息并将其发送到客户端的java程序当某个web应用没有缺省servlet时也会使用tomcatdefaultservlet作为默认缺省的servleservlet程序中只有属于同一个请求中的数据才可以通过httpservletrequest对象传递一个servlet只能映射一个虚拟路径一个元素下配置多个子元素能实现servlet的多重映射在servlet映射的路径中使用通配符格式只有两种
2. 在 login.html 中存在如下代码： <form action =”/LoginServlet” method=”post”>
java servlet选择题
以下是与Java Servlet相关的选择题：1. Servlet接口中，与Servlet生命周期相关的方法有（ ）个。
A．2 B．3 C．4 D．5答案：C解释：Servlet接口中，与Servlet生命周期相关的方法有init()、service()、doGet()、doPost()和destroy()共5个方法。
其中，init()方法是用于初始化Servlet的；service()方法是用于处理客户端的请求的；doGet()和doPost()方法是用于处理GET和POST请求的；destroy()方法是用于销毁Servlet 的。
2. Servlet接口中，共提供了（ ）个方法。
A．2 B．3 C．4 D．5答案：B解释：Servlet接口中，共提供了3个方法，包括init()、service()和destroy()。
这些方法用于Servlet 的生命周期中。
3. 下列关于Servlet的说法，有误的是（ ）。
A．Servlet是基于Java语言的Web服务器编程技术B．一个Servlet程序是一个运行在服务器的特殊Java类C．Servlet能够处理来自客户端的请求，但不生成响应D．Servlet具有可移植好、效率高等优点答案：C解释：选项A、B和D都是正确的说法。
而选项C错误，因为Servlet能够处理来自客户端的请求，并生成响应。
4. 与HttpSessionListener接口有关的方法是（ ）。
A．servlet-mapping B．servlet-class C．url-pattern D．tag答案：A解释：HttpSessionListener接口是用于监听HttpSession对象的创建和销毁事件的。
在Servlet中，可以通过实现HttpSessionListener接口来监听session的生命周期事件。
与HttpSessionListener接口有关的方法是servlet-mapping，它用于配置servlet在web.xml中的映射。
Vue集成vue-pdf进行pdf预览
Vue集成vue-pdf进⾏pdf预览1、安装vue-pdfnpm install --save vue-pdf2、前端⽰例代码如下<template><div class="pdf" v-show="fileType === 'pdf'"><sticky class-name="sub-navbar"><Button @click="handelCancel" icon="md-undo">返回</Button></sticky><div v-if="fileList!=null && fileList.length > 0"><label class="prev" @click="prevPage" v-if="currentIndex != 1">上⼀篇</label><pdfv-if="change"v-for="i in numPages":key="i":src="src":page="i"style="display: inline-block; width: 100%"></pdf><label class="next" @click="nextPage" v-if="currentIndex < fileList.length">下⼀篇</label></div><div v-else><h1>⽆PDF⽂件</h1></div></div></template><script>// npm install --save vue-pdfimport pdf from 'vue-pdf'import {getPdfListByRelationId, getPdfListByProjectId} from '@/api/target-attachment'export default {components: {pdf},data() {return {change: true,fileType: 'pdf', // ⽂件类型src: '', // pdf⽂件地址numPages: 1,flowSonStepId: this.$route.query.flowSonStepId,projectId: this.$route.query.projectId,fileList: [],currentIndex: 1}},mounted() {let _this = thiswindow.addEventListener('popstate', function () {_this.$watermark.set('')},false)this.$watermark.set('嘉定区产业项⽬全流程服务信息系统')this.getPdfList()},methods: {// 初始化获取pdf⽂件getPdfList() {let _this = thisif (this.flowSonStepId){getPdfListByRelationId(this.flowSonStepId).then(res => {if (res.code === 200) {_this.fileList = res.data_this.getPdfCode()}})}else if(this.projectId){getPdfListByProjectId(this.projectId).then(res => {if (res.code === 200) {_this.fileList = res.data_this.getPdfCode()}})}},// 初始化获取pdf⽂件if (_this.fileList != null && _this.fileList.length > 0) {let fileLoadUrl = window.configs.testUrlswitch (process.env.NODE_ENV) {case 'test':fileLoadUrl = window.configs.testUrlbreakcase 'production':fileLoadUrl = window.configs.proUrlbreak}_this.loadPDF(fileLoadUrl + "/file/loadPdfFile/" + _this.fileList[0].id)}},prevPage() {this.currentIndex--},nextPage() {this.currentIndex++},loadPDF(pdfUrl) {this.change = falselet self = thislet loadingTask = pdf.createLoadingTask(pdfUrl)console.log(loadingTask)loadingTask.promise.then(pdf => {self.src = loadingTaskself.numPages = pdf.numPages}).catch((err) => {console.error('pdf加载失败')})this.change = true},handelCancel() {this.$watermark.set('')this.$router.go(-1)}}}</script><style>.prev {position: absolute;top: 50%;z-index: 100;}.next {position: absolute;top: 50%;z-index: 100;right: 10px}#app{overflow-y: auto;}</style>3、后端⽰例代码@RestController@RequestMapping("pdf")public class PdfController {@GetMapping("downloadFile/{fileName}")public void downloadFile(@PathVariable("fileName") String fileName, HttpServletResponse response) {response.setHeader("content-type", "application/octet-stream");response.setContentType("application/octet-stream");try {response.setHeader("Content-Disposition", "attachment;filename=" + .URLEncoder.encode(fileName, "UTF-8")); } catch (UnsupportedEncodingException e2) {e2.printStackTrace();}byte[] buff = new byte[1024];BufferedInputStream bis = null;OutputStream os = null;try {String path = "D:\\Ch";os = response.getOutputStream();bis = new BufferedInputStream(new FileInputStream(new File(path + "\\" + fileName + ".pdf")));int i = bis.read(buff);while (i != -1) {os.write(buff, 0, buff.length);}} catch (FileNotFoundException e1) { } catch (IOException e) {e.printStackTrace();} finally {if (bis != null) {try {bis.close();} catch (IOException e) {e.printStackTrace();}}}}}。
第2天：servlet常见的接口和方法
第2天：servlet常见的接⼝和⽅法1、常见接⼝：2、ServletRequset接⼝Servlet容器对于接受到的每⼀个Http请求，都会创建⼀个ServletRequest对象，并把这个对象传递给Servlet的Sevice( )⽅法。
其中，ServletRequest对象内封装了关于这个请求的许多详细信息。
常⽤的⽅法：public interface ServletRequest {Map<String, String[]> getParameterMap();//返回请求主体参数的key-valueString getContentType();//返回主体的MIME类型String getParameter(String var1);//返回请求参数的值}3、ServletResponse接⼝javax.servlet.ServletResponse接⼝表⽰⼀个Servlet响应，在调⽤Servlet的Service( )⽅法前，Servlet容器会先创建⼀个ServletResponse对象，并把它作为第⼆个参数传给Service( )⽅法。
ServletResponse隐藏了向浏览器发送响应的复杂过程。
⽅法：public interface ServletResponse {String getCharacterEncoding();String getContentType();ServletOutputStream getOutputStream() throws IOException;PrintWriter getWriter() throws IOException;void setCharacterEncoding(String var1);void setContentLength(int var1);void setContentLengthLong(long var1);void setContentType(String var1);void setBufferSize(int var1);int getBufferSize();void flushBuffer() throws IOException;void resetBuffer();boolean isCommitted();void reset();void setLocale(Locale var1);Locale getLocale();}其中的getWriter()⽅法，它返回了⼀个可以向客户端发送⽂本的的Java.io.PrintWriter对象。
java获取数据并转换为pdf的方法
java获取数据并转换为pdf的方法Java中可以使用第三方库iText来生成PDF文件。
下面是一个简单的示例代码，演示如何使用iText生成PDF文件并将数据写入其中：javaimport java.io.FileOutputStream;import com.itextpdf.text.Document;import com.itextpdf.text.Element;import com.itextpdf.text.Paragraph;import com.itextpdf.text.pdf.PdfWriter;public class PDFGenerator {public static void main(String[] args) throws Exception {// 创建PDF文档Document document = new Document();PdfWriter.getInstance(document, new FileOutputStream("example.pdf"));// 打开文档document.open();// 写入数据Paragraph paragraph = new Paragraph("Hello World!");document.add(paragraph);// 关闭文档document.close();}}在上面的代码中，我们首先创建了一个PDF文档对象，然后使用PdfWriter类将其写入到文件中。
接下来，我们打开文档，创建一个包含文本"Hello World!"的段落，并将其添加到文档中。
最后，我们关闭文档。
执行该程序后，将生成一个名为"example.pdf"的PDF文件，其中包含文本"Hello World!"。
需要注意的是，iText库需要单独下载并添加到Java项目中。
java解析pdf的原理
java解析的原理
Java解析PDF的原理是通过使用PDF解析库来读取PDF文件的内容，提取其中的文本、图像和图形等信息，并进行解析和处理。
Java解析PDF的原理是通过解析PDF文件的结构和内容，将其中的文本、图像和图形等信息提取出来，并转换成Java可用的格式进行处理和展示。
在这个过程中，需要使用PDF解析库来辅助完成解析操作。
具体的解析过程如下：
1. 打开PDF文件：使用Java的文件操作库打开PDF文件，并读取其中的内容。
2. 解析文件结构：PDF文件采用的是二进制格式，需要解析其文件结构。
PDF文件由多个对象组成，包括页面、字体、图像等。
3. 解析字体信息：PDF文件中的文本通常使用字体进行描述。
解析器会读取PDF 文件中的字体信息，并将其保存为Java可用的格式。
4. 解析页面信息：PDF文件由多个页面组成，每个页面包含了文本、图像和图形等元素。
解析器会读取并保存每个页面的信息。
5. 提取文本内容：解析器通过解析页面信息，提取文本内容。
根据PDF文件中的字体信息，将文本内容转换成可读的格式。
6. 提取图像信息：PDF文件中可能含有嵌入的图像。
解析器会读取图像的信息，并将其保存为Java可用的格式，如BufferedImage。
7. 处理图形信息：PDF文件中的图形通常是由矢量图形描述的。
解析器会读取图形的绘制指令，将其转换成Java中的图形绘制指令。
8. 关闭文件：解析器读取完PDF文件的内容后，会关闭文件以释放相关资源。
创建PDF模板，java添加内容、导出下载PDF
创建PDF模板，java添加内容、导出下载PDF 本⽂主要内容是：⽤java在pdf模板中加⼊数据，图⽚。
废话不多说，举个⾮常简单的例⼦：⾸先创建word⽂档,导出PDF。
⽤软件adobe acrobat打开，操作步骤如图：在指定位置添加⽂本域，保存退出。
pdf模板创建完成，我们保存到 E：盘，起名叫练习。
接下来是java内容。
在pom.xml⽂件加⼊，<!-- itext 图⽚转pdf --><dependency><groupId>com.itextpdf</groupId><artifactId>itextpdf</artifactId><version>5.5.10</version></dependency>在Controller层创建，节约时间直接附上代码package com.boot.controller;import java.io.OutputStream;import java.io.UnsupportedEncodingException;import .URLEncoder;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;import java.util.HashMap;import java.util.Map;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.itextpdf.text.Image;import com.itextpdf.text.Rectangle;import com.itextpdf.text.pdf.AcroFields;import com.itextpdf.text.pdf.BaseFont;import com.itextpdf.text.pdf.PdfContentByte;import com.itextpdf.text.pdf.PdfReader;import com.itextpdf.text.pdf.PdfStamper;@RestControllerpublic class PdfController {/*** 导出pdf* @author Changhai* @param response* @return* @throws UnsupportedEncodingException*/@RequestMapping(value={"/exportpdf"})public String exportPdf(HttpServletResponse response) throws UnsupportedEncodingException { // 指定解析器System.setProperty("javax.xml.parsers.DocumentBuilderFactory",".apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl");//String path = request.getSession().getServletContext().getRealPath("/upload/");String filename="练习.pdf";String path="e:/";response.setContentType("application/pdf");response.setHeader("Content-Disposition", "attachment;fileName="+ URLEncoder.encode(filename, "UTF-8"));OutputStream os = null;PdfStamper ps = null;PdfReader reader = null;try {os = response.getOutputStream();// 2 读⼊pdf表单reader = new PdfReader(path+ "/"+filename);// 3 根据表单⽣成⼀个新的pdfps = new PdfStamper(reader, os);// 4 获取pdf表单AcroFields form = ps.getAcroFields();// 5给表单添加中⽂字体这⾥采⽤系统字体。
getPDF.jsp
I. INTRODUCTION Electric vehicles (EV’s) have been around since before the tum of the century. They were very popular and sold reasonably well until about 1918. However, the use of EV’s for transportation died out as the gasoline powered intemal combustion engine (ICE) continued to improve [ 11. By 1933, the number of EV’s was reduced to nearly zero because the EV was slower and more expensive than its ICE counterpart. The shortcomings which caused the EV to lose its early competitive edge have not yet been totally overcome. Significant advances in power electronics and microelectronics have been utilized to make EV powertrains that provide performance competitive with ICE powertrains. Although there have been no similar advances in battery energy storage, the evolution of materials and production technologies provide means to achieve the optimistic battery system goals. Significant factors which stimulate the revival of EV’s are energy cost, energy independence, and environmental protection. Because of the upcoming shortage of gasoline products, their cost and limitations in supply have encouraged people to look at EV’s as a possible alternative mode of transportation.As electricity can be generated from many alternate energy resources, EV’s are the ultimate flexible fuel vehicle. Moreover, they are generally recharged when power utilities have excess energy available. The major reason for the rekindling of interest in EV’s are environmental considerationsthat electricity is superior to gasoline. EV’s can dramatically reduce air pollution in congested
java从远程服务器获取PDF文件并后台打印（使用pdfFox）
java从远程服务器获取PDF⽂件并后台打印（使⽤pdfFox）⼀、java原⽣⽅式打印PDF⽂件正反⾯都打印，还未研究出只打印单⾯的⽅法，待解决public static void printFile(String path) throws Exception {File file = new File(path);File[] fies=file.listFiles();for(File f:fies){System.out.println("file "+f.getName());String fileExt=f.getName().substring(f.getName().indexOf(".")+1,f.getName().length());if("pdf".equalsIgnoreCase(fileExt)){String filepath=path+File.separator+f.getName();File pdfFile=new File(filepath);//构建打印请求属性集PrintRequestAttributeSet pras = new HashPrintRequestAttributeSet();//设置打印格式，因为未确定⽂件类型，这⾥选择AUTOSENSEDocFlavor flavor = DocFlavor.INPUT_STREAM.AUTOSENSE;//查找所有的可⽤打印服务PrintService printService[] = PrintServiceLookup.lookupPrintServices(flavor, pras);//定位默认的打印服务PrintService defaultService = PrintServiceLookup.lookupDefaultPrintService();//显⽰打印对话框//PrintService service = ServiceUI.printDialog(null, 200, 200, printService, defaultService, flavor, pras);if(defaultService!=null){DocPrintJob job = defaultService.createPrintJob(); //创建打印作业FileInputStream fis = new FileInputStream(pdfFile); //构造待打印的⽂件流DocAttributeSet das = new HashDocAttributeSet();Doc doc = new SimpleDoc(fis, flavor, das); //建⽴打印⽂件格式job.print(doc, pras); //进⾏⽂件的打印}f.delete();}}}public static void main(String[] args) {//System.out.println("Value:"+test());//打印pdf的⼀个⽅法，⾸先安装下PDFCreator软件try {printFile("D:"+File.separator);} catch (Exception e) {System.out.println("打印⽂件异常："+e.getMessage());e.printStackTrace();}}View Code⼆、使⽤pdfBox⽅式此问题解决1.maven依赖<dependency><groupId>org.apache.pdfbox</groupId><artifactId>pdfbox</artifactId><version>2.0.3</version></dependency>View Code2.代码（有打印预览）import java.awt.print.Book;import java.awt.print.PageFormat;import java.awt.print.Paper;import java.awt.print.PrinterException;import java.awt.print.PrinterJob;import java.io.*;import .HttpURLConnection;import .URL;import javax.print.attribute.HashPrintRequestAttributeSet;import javax.print.attribute.PrintRequestAttributeSet;import javax.print.attribute.standard.PageRanges;import org.apache.pdfbox.pdmodel.PDDocument;import org.apache.pdfbox.printing.PDFPageable;import org.apache.pdfbox.printing.PDFPrintable;public final class PrintUtils{public static void main(String[] args) {String fileURL = "http";String fileName = ".pdf⽂件";downloadFile(fileURL,fileName);printWithDialog(getFilePath(fileName));}public static void printWithDialog(String filePath) {try {PDDocument document = PDDocument.load(new File(filePath));PrinterJob job = PrinterJob.getPrinterJob();job.setPageable(new PDFPageable(document));if (job.printDialog()){job.print();}} catch (IOException e) {e.printStackTrace();} catch (PrinterException e) {e.printStackTrace();}}public static String getFilePath(String fileName){File path = new File(System.getProperty("user.dir").concat("/downFile"));if (!path.exists() && !path.isDirectory()) {path.mkdir();}String filePath = path + "/" + fileName;return filePath;}public static boolean downloadFile(String fileURL,String fileName) {try {URL url = new URL(fileURL);HttpURLConnection connection = (HttpURLConnection) url.openConnection();DataInputStream in = new DataInputStream(connection.getInputStream());DataOutputStream out = new DataOutputStream(new FileOutputStream(getFilePath(fileName)));byte[] buffer = new byte[4096];int count = 0;while ((count = in.read(buffer)) > 0) {out.write(buffer, 0, count);}out.close();in.close();return true;} catch (Exception e) {return false;}}}View Code。
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Ethanol reactions over Au–RhÕCeO2catalysts.Total decomposition and H2formationP.Y.Sheng and H.Idriss a)Department of Chemistry,The University of Auckland,Private Bag92019,Auckland,New Zealand͑Received27October2003;accepted15December2003;published21July2004͒The reaction of ethanol has been investigated on the surface of Au–Rh/CeO2by temperatureprogrammed desorption͑TPD͒,infrared spectroscopy and in steady state conditions.Most ofadsorbed ethanol is found in the form of ethoxides͑O–C at1045and1096cmϪ1͒.Heating thesurface resulted in the transformation of ethoxides to carbonates͑COO at1561and1347cmϪ1͒without the presence of stable acetaldehyde or formaldehyde species.By673K all surface specieshas been desorbed.The relative instability of these carbonates when compared to CeO2or Rh/CeO2indicates that Au is enhancing the rate of oxidation.Most of CO2formed during TPD is resultingfrom carbonate decomposition.Catalytic reactions showed that both CO2and H2can be formedwith high yield over a wide temperature range.©2004American Vacuum Society.͓DOI:10.1116/1.1705591͔I.INTRODUCTIONGold has now been receiving considerable attention since the important observation of Haruta’s and collaborators showing that when well dispersed on several supports͑such as Ti and Fe oxides͒it is very active for CO oxidation.1–5H2 as a source of energy is one of the mostly wanted fuel be-cause of its very high British thermal unit value and because its oxidation leads to H2O formation and is thus not directly contributing to further contamination of the environment by carbon containing products.6,7Among the potential sources for H2,ethanol is particularly attractive because of its re-newable origin͑biofuel͒.8In this work we present a funda-mental study of ethanol reaction on the surface of a Au–Rh/CeO2catalyst and compare it to that on CeO2,9 Rh/CeO2,10and Au/CeO2.11For example we have shown that the adsorption of ethanol on Rh/CeO2leads directly to carbon–carbon bond dissociation10while that on Au/CeO2 mainly results in ethoxide species.11Moreover,while consid-erable amounts of CO were detected over Rh/CeO2from ethanol,Au/CeO2has shown high formation of CO2.The main objectives of this work are the following.͑1͒To see into the combined effect of Au and Rh on the surface species as probed by in situ infrared͑IR͒.͑2͒To probe the reaction pathway by temperature programmed desorption͑TPD͒.͑3͒To obtain direct information from catalytic reaction of etha-nol on the surface in steady state conditions and compare them to stoichiometric reactions by TPD and in situ IR. II.EXPERIMENTCerium oxide(CeO2)was prepared by precipitating white crystalline cerous nitrate͓Ce͑NO3)3•6H2O]͑100g͒,dis-solved in de-ionized water at373K,using ammonia͑0.91 mol LϪ1͒at a p H of8.The resulting white slurry precipitate was than collected byfiltration,washed with de-ionized wa-ter,and left to dry in an oven at373K for12h.The pale purple dried powder was calcined in a furnace at773K for4 h withflowing air.The sample was then ground but not sieved to a consistent powder.Stock solutions of Rh͑ex. RhCl3)and Au͑ex.51%Au in1g of tetra chloroauric acid͒were made in1M of hydrochloric acid.The monometallic and bimetallic catalysts1wt%Au/CeO2and 1wt%Au–1wt%Rh/CeO2were prepared by impregna-tion,followed by drying and calcination at673K for4h. The1wt%will be omitted in the remaining of the manu-script for simplicity.Catalysts were characterized by Brunauer–Emmett–Teller͑BET͒surface area measurements, x-ray diffraction͑XRD͒,and x-ray photoelectron spectros-copy͑XPS͒.IR study was conducted in situ as previously indicated9–11while steady state catalytic reactions were con-ducted in afixed bedflow reactor connected to two gas chro-matographs equipped with TCD andflame ionization detec-tor͑FID͒,as previously described elsewhere.9–11TPD studies were also conducted at the conditions given in details in Refs.9–11.Quantitative analyses of TPD are typical to what we have already conducted in Refs.9–13.More details of the experimental conditions will be given in the results part when necessary.III.RESULTSThe results will start by presenting a brief description of the characterization of the catalysts,followed by IR analyses of ethanol adsorption as a function of temperature in order to monitor irreversibly the adsorbed species and their evolution. TPD will then be presented and compared to IR results. Product distribution during steady state reactions will be pre-sented and compared to both IR and TPD results.IV.CHARACTERIZATIONBET surface areas of CeO2,Au/CeO2,and Rh–Au CeO2 were found equal to33,29,and26m2gϪ1,respectively.The decrease in BET area͑when compared to CeO2)might be due to blocking of some CeO2pores by the metal clusters.a͒Electronic mail:h.idriss@16521652 J.Vac.Sci.Technol.A22…4…,JulÕAug20040734-2101Õ2004Õ22…4…Õ1652Õ7Õ$19.00©2004American Vacuum SocietyThe fluorite CeO 2structure is maintained for all catalysts with an additional very small line at 2of 38.34°,corre-sponding to the ͑111͒cut,attributed to the small 1wt %of Au.Rh could not be seen ͑Fig.1͒.The mean particle dimen-sion for CeO 2computed from the ͑111͒,͑200͒,͑220͒,and ͑310͒lines is found very small in the nanometer size,equal to 15,18,and 15nm for CeO 2,Au/CeO 2,and Au–Rh/CeO 2,respectively.XPS ͑ex situ ͒was also con-ducted.CeO 2is partially reduced to Ce 3ϩ͑presence of Ce 3d 5/2and Ce 3d 3/2XPS lines at 886.9and 904.6eV at-tributed to v Јand u Ј,respectively ͒,XPS of CeO 2and CeO 2Ϫx were published by several workers,including our group,and it is not necessary to present them again here.13–16The presence of Au in both Au/CeO 2and Au–Rh/CeO 2was clear with Au 4f 7/2at 85.5Ϯ0.1eV that is most likely due to Au 2O 3clusters.17Rh was seen at 308.7Ϯ0.1eV (Rh 3d 5/2)indicating its presence,possibly as Rh 2O 3.18Table I shows the elemental distribution of the catalysts.V.SURFACE REACTIONSWe have previously investigated the reaction of ethanol on the surfaces of CeO 2,9Pd/CeO 2,9Pt/CeO 2,19Au/CeO 2,11and Rh/CeO 210by in situ IR.In brief,at room temperature the adsorption of ethanol is via the following channels:CeO 2⇒ethanol to ethoxides to acetates,Pt/CeO 2and Pd/CeO 2⇒ethanol to ethoxides to adsorbed acetaldehyde,andRh/CeO 2⇒ethanol to ethoxides to adsorbed CO.Rh was the only metal capable of breaking the C–C bond of ethanol at room temperature.While oxidation to acetates occurred only on CeO 2,the addition of any of the above metals has resulted in suppressing the room temperature oxi-dation to acetates.Figures 2and 3present IR regions scanned upon adsorption of ethanol on a self-supported Au–Rh/CeO 2at 295K ͑saturation exposure to ethanol was obtained at Ϸ2min,7Torr of ethanol ͒.All scans were con-ducted at 10Ϫ5Torr or lower.Figures 2͑a ͒and 2͑b ͒show the ethanol/ethoxide regions ͑O–C:1000–1200cm Ϫ1and C–H:2700–3000cm Ϫ1,respectively ͒.IR bands at 2971,2938,2905,2878,͑1451in Fig.3͒,1096,and 1044cm Ϫ1are attributed to the a (CH 3),a (CH 2),s (CH 3),s (CH 2),␦a (CH 3),͑CO ͒,and ͑CO ͒vibrational modes of ethoxides,respectively.The bands at 1096and 1044cm Ϫ1indicate that two types of ethoxy groups are present ͑monodentate and bidentate ͒on the surface as in the case of all M/CeO 2cata-lysts that we have investigated so far.9–11,19The main obser-vation from this figure is that ethoxides bands decreased with heating ͓all spectra are recorded at 295K,with a forced liquid N 2cooling from the indicated ͑flashed ͒temperatures ͔and disappeared by 673K.Ethoxides are transformed to other species ͑in addition to a partial hydrogenation back to ethanol ͒.The species resulting from ethoxide reactions are shown in Fig.3.Most of ethoxides have been oxidizedtoF IG . 1.X-ray diffraction of ͑a ͒CeO 2,͑b ͒Au/CeO 2,͑c ͒Au–Rh/CeO 2,and ͑d ͒Rh/CeO 2catalysts.A transmission electron mi-croscopy image of Rh/CeO 2catalyst shows the nanosize dimension of CeO 2in agreement with XRD analy-ses.T ABLE I.Atomic percent composition of each element as obtained from XPS analyses.Catalysts O Ce Au Rh M/Ce Au/CeO 269.7530.010.19¯0.006Au–Rh/CeO 258.6540.500.270.570.021JVST A -Vacuum,Surfaces,and Filmsand subsequentflashing to͑b͒343,͑c͒375,͑d͒425,͑e͒480,͑f͒520,͑g͒570,and͑h͒673K.F IG.3.CO͑a͒andCOO͑b͒band regions obtained by FTIR following adsorption of ethanol at300K͑a͒over Au–Rh/CeO2and subsequentflashing to ͑b͒343,͑c͒375,͑d͒425,͑e͒480,͑f͒520,͑g͒570,and͑h͒673K.J.Vac.Sci.Technol.A,Vol.22,No.4,JulÕAug2004F IG .4.TPD following adsorption of ethanol over Au–Rh/CeO 2͑a ͒at room temperature.Shown in ͑b ͒the noncorrected intensities of the IR peaks,corresponding to Figs.2and 3,as a function of temperature.T ABLE II.Relative yield,carbon yield,and percentage selectivity of products desorbing during ethanol-TPD on Au–Rh/CeO 2.ProductDesorption temperature ͑K ͒Relative yield %carbon yield %carbon selectivity Hydrogen 370,4400.006¯¯Methane 380,4300.4107.411.5Water400,500,565,6401.565¯¯Carbon monoxide 575–6950.243 4.4 6.8Carbon dioxide 690 1.36224.538.3Acetaldehyde 380,4300.75427.442.5Ethanol 370,420 1.00036.0¯Butadiene 475Ͻ0.001Ͻ0.1Ͻ0.1Butene 485Ͻ0.001Ͻ0.10.2Acetone 585Ͻ0.001Ͻ0.1Ͻ0.1Furan475Ͻ0.001Ͻ0.1Ͻ0.1Crotonaldehyde 480Ͻ0.001Ͻ0.1Ͻ0.1Benzene375,505,5500.0030.40.6T ABLE III.Mole percent yield of products from ethanol reaction over Au–Rh/CeO 2.473K573K 673K 773K 873K 973K 1073K CH 3CHO 66.60.7Ͻ0.1Ͻ0.1Ͻ0.1Ͻ0.1Ͻ0.1CH 418.019.017.014.411.211.012.6CH 3C ͑O ͒CH 3¯ 1.50.10.2¯¯¯CO ¯24.314.015.719.721.623.9CO 2¯49.456.254.653.752.849.0H 215.45.012.715.115.314.614.8JVST A -Vacuum,Surfaces,and Filmscarbonate species,presumably by a fast CO oxidation,upon breaking of the carbon–carbon bond of ethanol.Carbonates can be seen at 1561and 1347cm Ϫ1(a and s of monoden-tate carbonates ͒.20These surface carbonates are not very stable,however,since they are decomposed by 673K.Since Ce carbonates are relatively stable at 673K ͑see Fig.10in Ref.9͒it is thus likely that these carbonates are interfaced with Au and Rh oxide particle.Small amounts of CO are seen at 2089cm Ϫ1͑linear ͒with the absence of bridging CO ͑expected bands at Ϸ1900cm Ϫ1͒.Thus,the whole CO re-gion is totally different from that of Rh/CeO 2where clear formation of linear,bridging,and gem dicarbonyl CO spe-cies was seen from ethanol;10and in Fig.6in the discussion section.The observation of CO 2bands at 2458and 2346cm Ϫ1that are formed with increasing flashing temperatures,is probably due to irreversible adsorption of CO 2upon cool-ing;CO 2is most likely formed by the oxidation of some adsorbed CO and not from carbonates because the concen-tration of the latter was still rising.By 673K no species seem to be present on the surface.In order to follow the reaction products TPD was con-ducted and compared to IR data.Figure 4͑a ͒shows the TPD profile while the computed yield and selectivity is given in Table II.Unreacted ethanol (m /z ϭ31)desorbed in two do-mains at 370and 420K.It accounted for nearly 35%of the total carbon yield.Acetaldehyde (m /z ϭ29)desorbed in two temperature domains at 380and 430K with a combinedselectivity of 42%.Methane (m /z ϭ15)desorption peaks were found at 380and 430K,coinciding with those of ac-etaldehyde.After subtraction of acetaldehyde contribution to the m /z 15,the total selectivity for methane was found equal to 12%.Products formed immediately after ethanol desorp-tion were water,and hydrogen.͑See Table III.͒Water (m /z ϭ18)was found to desorb in four temperature domains at 400,500,565,and 640K.Hydrogen (m /z ϭ2)desorbed at 370and 440K.Ethylene desorption was not observed.In the high temperature domain,CO and CO 2were detected.Trace amounts of acetone (m /z 58)were found to desorb at 585K.Other hydrocarbons such as butadiene (m /z ϭ54)at 475K,butene (m /z ϭ56)at 485K,furan (m /z ϭ68),and crotonal-dehyde (m /z ϭ70)desorbed at 480K.Benzene (m /z ϭ78)gave three desorption peaks located at 375,505,and 550K.All these hydrocarbon products combined represented ϳ7%of the amount of converted ethanol.Figure 4͑b ͒shows the uncorrected intensity of the IR bands of Figs.2and 3.The relationship between ethanol desorption and ethoxide species consumption is clear.Acetaldehyde desorption is most likely due to ethoxide dehydrogenation requiring an activation en-ergy higher than that for its adsorption energy ͑desorption is reaction limited ͒since IR have shown very small amounts.Most of CO and CO 2during TPD ͓Fig.4͑a ͔͒are probably provided from carbonate decomposition ͓Fig.4͑b ͔͒.F IG .5.Steady state catalytic reactions of ethanol/O 2͑1/1.5͒as a function of reaction temperature.Shown in ͑a ͒are ethanol,acetaldehyde,acetone,and methane while in ͑b ͒are CO,CO 2,andH 2.Amount of catalyst:50mg,total flow rate ϭ200ml min Ϫ1͑containing O 2with N 2as balance ͒,reactor volume 8ml.͓Ethanol ͔ϭ3ϫ10Ϫ6mol ml Ϫ1.The inset shows the rate of ethanol consumption ͑mol g Ϫ1min Ϫ1͒as a function of temperature.J.Vac.Sci.Technol.A,Vol.22,No.4,Jul ÕAug 2004VI.CATALYTIC REACTIONSResults of steady state reactions are given in Figs.5͑a͒and5͑b͒and Table III.Figure5͑a͒shows products detected by FID while those by TCD are given in Fig.5͑b͒.All prod-ucts are corrected to externally calibrated gases.Ethanol was cofed with O2at a ratio1:1.5.Changing the ratio to1:2did not result in a considerable change.Initial runs were con-ducted in order to work in an optimum ethanol to O2ratios using an on line mass spectrometer.Higher ratios resulted in higher conversion but less H2production͑in favor of water formation͒,while ratios less than one were not practical for an efficient decomposition.The main differences between stoichiometric and catalytic reactions are the following.͑1͒Continuous feeding of ethanol at high temperatures in the presence of oxygen results in considerable methane forma-tion;that decreases at still higher temperatures.͑2͒Both CO and CO2are formed at lower temperatures than during TPD. The ratio CO/CO2is in general larger than during TPD.͑3͒H2formation was clear at high temperature and remained relatively unchanged with further increasing temperatures. VII.DISCUSSIONThe main results from this work are as follows.͑1͒Most of the adsorbed species upon ethanol exposure at room temperature are in the form of ethoxide species.͑2͒A competition between hydrogenation of these ethoxide species͑to ethanol͒and their further oxidation͑to acetal-dehyde then to CH4and surface carbonates͒occurs.͑3͒In presence of oxygen,most of gas phase ethanol reacts by600K to give CO and CO2with non-negligible amount of hydrogen͑about15mol%of the reactionproduct͒.The discussion will focus on two points.͑i͒The change ofthe reaction activity and selectivity of CeO2with the additionof the noble metals.͑ii͒The differences and similarities be-tween the reaction of Rh/CeO2and that of Au–Rh/CeO2.͑i͒Although not presented here ethanol adsorption on CeO2results in the almost exclusive formation of acetatespecies:9CH3CH2OH͑a)ϩ3͓O͔→CH3COO͑a)ϩH2OϩOH͑a). CeO2is an excellent oxidation catalyst and as such the oxi-dation of ethanol to stable acetates is intuitive.20–22 The addition of Au,Rh,or both metals in very small amountϽ2at.%resulted in the suppression of this route. This is due to two factors that are both thermodynamically driven.First,the addition of the metal has partially reduced the CeO2surface even at ambient conditions͑as evidenced by ex situ XPS͒and this will hinder the capacity of CeO2to further oxidize ethanol in stoichiometric conditions͑TPD and IR͒.Second,ethoxide species are stabilized by the pres-ence of the metal͑present as dominant species͒;in other words diffusion of ethoxides occurs from CeO2surfaces to M y–O x/CeO2Ϫx͑assuming that most of the oxygen used to oxidize the Au or Rh is taken from CeO2and that M is present mainly in M2O3form͒.A recent study of Au/CeO2 has shown that Au cations are also present and are most likely the active center for the water gas shift reaction.23͑ii͒Comparing ethanol reaction on Rh/CeO2͑Fig.6͒to that on Au–Rh/CeO2͓Fig.3͑a͔͒,shows that CO and acetal-dehyde formation on the surface from ethanol are character-istic of Rh/CeO2.In presence of Au,Rh has lost its capacity to stabilize CO,most likely because of a fast oxidation to carbonates and CO2.The addition of Au to Rh has resulted in a behavior similar to that of Au/CeO2,yet more active (Au/CeO2IR data are presented elsewhere͒;11they qualita-tively differ little from those of Au–Rh/CeO2).The main effect of Au on Rh/CeO2is the considerable formation of CO2,and this can be tracked͑according to IR data͒to sur-face carbonates.The CO2/CO͑obtained during ethanol-TPD͒for Au–Rh/CeO2is5.6while that of Rh/CeO2is1.8;10 although far less than that of Au/CeO2(CO2/COϭ24)11it is nevertheless a threefold increase.In summary,from TPD,IR,and steady state catalytic re-actions results it appears that Au–Rh/CeO2is a more active than Au/CeO2and more selective than Rh/CeO2catalysts for the oxidation of ethanol.The production of H2is sustained at a wide range of temperature with relatively large amounts of CO2when compared to Rh/CeO2catalystsalone.F IG.6.FTIR after adsorption of ethanol over Rh/CeO2at309K and con-sequent annealing at increment temperatures to473K.The bands at1700 cmϪ1are due to1-CH3CHO,while those at1900–2100cmϪ1are due to several modes of adsorption of CO͑mainly linear and bridging modes͒.JVST A-Vacuum,Surfaces,and Films1M.Haruta,N.Yamada,T.Kobayashi,and S.Iijima,J.Catal.115,301͑1989͒.2M.Haruta,S.Tsubota,T.Kobayashi,H.Kageyama,M.J.Genet,and B. 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