计算机网络原理实验(Web服务端)

Experiment Report of Computer Network’s Theory——Web Server(JAVA)Designer’s Name:Guidance Counselors:Profession:Student ID:ContentExperiment Purpose 2Experiment RequestingDesign Ideas and ThoughtCode DescriptionOperation Effect and ResultResult Explanation 12Improvable Part 13Experiment Conclusion 131.E xperiment Purpose1）Deal with a Http Request2）Receiving and analyzing a Http Request3）Attain the requested files from the server file system 4）Establish a http respond message including therequested files5）Send the message to client directly2.E xperiment Requesting1）We should install SDK at first, we can follow the guidance given by 《Instruction of Experiment》.2）Run the code we have edited and see the result only when we just have some compile platform for java.3）For check the result, we can put the edited html files into the folder where server exists at first, then weshould open our browser and input the direct stringsuch as http://196.168.0.2:8080/I:index.html intoaddress bar.4）Follow 3）, if we can just open the webpage and see the content, we can ensure that the web server weestablished is no problem. Else, we need to checkwhere we failed.3.D esign Idea and ThoughtWe have just learned about the theory of http protocols and got the knowledge of server and client. But when we edit the code, thing seems not to be so easy.At this experiment, we use java language and eclipse software to achieve our goals.First of all, we need a class to connect with our browser, for this idea, we establish a class which extends Thread. After that, we need a variable to record the connection times, when the number beyond a special value, we must close theweb server, which means connection is failed!Then, we need to come up with a way to solve such a problem as follow:1）How can the Web Server “understand”the request that our browsers have just sent?2）If the type of this request is “get”, how can the Web Server know which files our browsers need?3）While such a file or files does or do not exist, which action does Web Server should take? (E.g.what kind of message does Web Server shouldrespond to our browsers?)4）At last, we need to seek for a way that Web Server can send the right file or files to client directly.Only when we solve these problems, can we really establish a true-meaning webserver.On the next part, we will show how we solve these problems by explaining the code we have edited!4.C ode Descriptionimport java.io.*;import .*;At the beginning, we imported two main packages that we need.publicclass WebServer {publicstaticvoid main(String args[]) { //主函数int i=1, PORT=8080; //端口设置为8080We defined the socket number we use is 8080 ServerSocket server=null; //创建一个ServerSocket类，同时在运行该语句的计算机的指定端口处建立一个监听服务Socket client=null; //当Client程序需要从Server端获取信息及其他服务时，应创建一个Socket对象The notes we edited have explained well, we do not explain more here.try {server=new ServerSocket(PORT); //在8080端口设置监听服务System.out.println("Web Server is listening on port"+server.getLocalPort());//这只是一个测试The above sentence is not necessary, we can delete such sentence. In our real life, such tips we cannot see.for (;;){client=server.accept(); //接受客户机的连接请求new ConnectionThread(client,i).start();i++; //i用于存放请求数}} catch (Exception e) {System.out.println(e);}}}The above sentence is important, which is the core of Main Function——we connected server with client, and count the connection times.We can see such a fact that if the count number is beyond a special value, we would close the server from the definition of Connection Thread Function./* ConnnectionThread类完成与一个Web浏览器的通信 */class ConnectionThread extends Thread {Socket client; //连接Web浏览器的socket字int counter; //计数器public ConnectionThread(Socket cl,int c) { //构造函数client=cl;counter=c;}Constructors’inlet parameter is defined by specific socket and current connection numberpublicvoid run() //线程体{try {String destIP=client.getInetAddress().toString(); //客户机IP地址int destport=client.getPort(); //客户机端口号System.out.println(destIP);System.out.println("Connection "+counter+"：connected to"+destIP+" on port "+destport+".");//该语句用于测试All the sentences about “System.out.println” are not necessary, only used for test,No longergive unnecessary details after.PrintStreamoutstream=new PrintStream(client.getOutputStream());DataInputStreaminstream=new DataInputStream(client.getInputStream( ));String inline=instream.readLine(); //读取Web浏览器提交的请求信息From now on, it’s time to the communication which between server and client starts.System.out.println("Received："+inline); //该语句用于测试if(getrequest(inline)) { //如果是GET请求 String filename=getfilename(inline);File file=new File(filename);if (file.exists()) { //若文件存在,则将文件送给Web浏览器System.out.println(filename+" requested.");outstream.println("HTTP/1.0 200 OK");outstream.println("MIME_version：1.0");outstream.println("Content_Type：text/html");int len=(int)file.length();outstream.println("Content_Length："+len);outstream.println("");sendfile(outstream,file); //发送文件outstream.flush();}The Above sentences are based on the form of Message between server and client.else { //文件不存在时String notfound="Error 404-file not found";outstream.println("HTTP/1.0 404 no found");outstream.println("Content_Type：text/html");outstream.println("Content_Length："+notfound.length()+2);outstream.println("");outstream.println(notfound);outstream.flush();}}long m1=1;while (m1<11100000) {m1++;} //延时client.close();} catch (IOException e) {System.out.println("Exception："+e);}}/* 获取请求类型是否为“GET” */The Above sentences are based on the format of Message in webpage in common use.boolean getrequest(String s) {if (s.length()>0){if (s.substring(0,3).equalsIgnoreCase("GET")) returntrue;}returnfalse;}/* 获取要访问的文件名 */String getfilename(String s) {String f=s.substring(s.indexOf(' ')+1);f=f.substring(0,f.indexOf(' '));try {if (f.charAt(0)=='/')f=f.substring(1);} catch (StringIndexOutOfBoundsException e) {System.out.println("Exception："+e);}if (f.equals("")) f="index.html";return f;}/*把指定文件发送给Web浏览器 */void sendfile(PrintStreamouts,File file) {try {DataInputStreamin=new DataInputStream(new FileInputStream(file));int len=(int)file.length();byte buf[]=newbyte[len];in.readFully(buf);outs.write(buf,0,len);outs.flush();in.close();} catch (Exception e) {System.out.println("Error retrieving file.");System.exit(1);}}}At last, we send the right file our browsers requested to client.5.O peration Effects and ResultsAt first, we should state that our website pathway is “D: /workplace/WEB”, and the html file used for testing is “index.html” which has been put in website folder.Then, we need to find our IP site:Now, let’s check our Web Server!1）Run the code we have edited.2）Input the right address in our browser’s address bar. —http://219.242.120.11:8080/D:/workplace/WEB/index.html3）Fortunately, we got the right webpage we need!4）At last, we can test more——close the web server ,and input the address again, we can observe such situation!6.R esults ExplanationAs all we know, our web server is successful! When weopen our web server, it starts to wait for any request message from clients wherever. We input the right address (current socket number is 8080, not 80), and web server receive our request and respond to us by sending the html file we need.While we close the web server, we cannot get the right html file after input the address, just because the socket number of 8080 is meaningless now.7.I mportable PartNothing is perfect, there is an apparent weakness is that when we want to close the web server, we must close all the project and software which supporting the code. It’s so inconvenient, and we want to have the function that we can easily handle the running state of web server, for example, we want to close the web server after 8:00 pm every day and open it in the morning and so on.However, such function is additional; we may not have the necessity to add a function whose meaning is a little.8.E xperiment ConclusionWe should be glad to have the chance to operate the experiment at first, no one can learn all only from theories without practices.From such an experiment, we can acquire a deeperunderstanding about Http Protocols and the processes of message require and respond. Besides, we also strengthen our skill of programming either in fact.Generally speaking, we catch the core of the http protocols, and achieve our original goals!。