java的http断点续传原理(二)

java的http断点续传原理(二)

//获得文件长度

public long getFileSize()

{

int nFileLength = -1;

try{

URL url = new URL(siteInfoBean.getSSiteURL());

HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); httpConnection.setRequestProperty("User-Agent","NetFox");

int responseCode=httpConnection.getResponseCode();

if(responseCode>=400)

{

processErrorCode(responseCode);

return -2; //-2 represent access is error

}

String sHeader;

for(int i=1;;i++)

{

//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); //Utility.log(in.readLine());

sHeader=httpConnection.getHeaderFieldKey(i);

if(sHeader!=null)

{

if(sHeader.equals("Content-Length"))

{

nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); break;

}

}

else

break;

}

}

catch(IOException e){e.printStackTrace ();}

catch(Exception e){e.printStackTrace ();}

Utility.log(nFileLength);

return nFileLength;

}

//保存下载信息(文件指针位置)

private void write_nPos()

{

try{

output = new DataOutputStream(new FileOutputStream(tmpFile));

output.writeInt(nStartPos.length);

for(int i=0;i< p>

{

// output.writeLong(nPos[i]);

output.writeLong(fileSplitterFetch[i].nStartPos);

output.writeLong(fileSplitterFetch[i].nEndPos);

}

output.close();

}

catch(IOException e){e.printStackTrace ();}

catch(Exception e){e.printStackTrace ();}

}

//读取保存的下载信息(文件指针位置)

private void read_nPos()

{

try{

DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); int nCount = input.readInt();

nStartPos = new long[nCount];

nEndPos = new long[nCount];

for(int i=0;i< p>

{

nStartPos[i] = input.readLong();

nEndPos[i] = input.readLong();

}

input.close();

}

catch(IOException e){e.printStackTrace ();}

catch(Exception e){e.printStackTrace ();}

}

private void processErrorCode(int nErrorCode) {

System.err.println("Error Code : " + nErrorCode); }

//停止文件下载

public void siteStop()

{

bStop = true;

for(int i=0;i< p>

fileSplitterFetch[i].splitterStop();

}

}

/*

**FileSplitterFetch.java

*/

package NetFox;

import java.io.*;

import .*;

public class FileSplitterFetch extends Thread {

String sURL; //File URL

long nStartPos; //File Snippet Start Position

long nEndPos; //File Snippet End Position

int nThreadID; //Thread's ID

boolean bDownOver = false; //Downing is over

boolean bStop = false; //Stop identical

FileAccessI fileAccessI = null; //File Access interface

public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException

{

this.sURL = sURL;

this.nStartPos = nStart;

this.nEndPos = nEnd;

nThreadID = id;

fileAccessI = new FileAccessI(sName,nStartPos);

}

public void run()

{

while(nStartPos < nEndPos && !bStop)

{

try{

URL url = new URL(sURL);

HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();

httpConnection.setRequestProperty("User-Agent","NetFox");