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http断点续传简单实现

王朝other·作者佚名  2008-05-31
窄屏简体版  字體: |||超大  

/*

**SiteFileFetch.Java

*/

package NetFox;

import java.io.*;

import java.net.*;

public class SiteFileFetch extends Thread {

SiteInfoBean siteInfoBean = null; //文件信息Bean

long[] nStartPos; //开始位置

long[] nEndPos; //结束位置

FileSplitterFetch[] fileSplitterFetch; //子线程对象

long nFileLength; //文件长度

boolean bFirst = true; //是否第一次取文件

boolean bStop = false; //停止标志

File tmpFile; //文件下载的临时信息

DataOutputStream output; //输出到文件的输出流

//负责整个文件的抓取,控制内部线程(FileSplitterFetch类)

public SiteFileFetch(SiteInfoBean bean) throws IOException

{

siteInfoBean = bean;

//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath()));

tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info");

if(tmpFile.exists ())

{

bFirst = false;

read_nPos();

}

else

{

nStartPos = new long[bean.getNSplitter()];

nEndPos = new long[bean.getNSplitter()];

}

}

public void run()

{

//获得文件长度

//分割文件

//实例FileSplitterFetch

//启动FileSplitterFetch线程

//等待子线程返回

try{

if(bFirst)

{

nFileLength = getFileSize();

if(nFileLength == -1)

{

System.err.println("File Length is not known!");

}

else if(nFileLength == -2)

{

System.err.println("File is not Access!");

}

else

{

for(int i=0;i<nStartPos.length;i++)

{

nStartPos[i] = (long)(i*(nFileLength/nStartPos.length));

}

for(int i=0;i<nEndPos.length-1;i++)

{

nEndPos[i] = nStartPos[i+1];

}

nEndPos[nEndPos.length-1] = nFileLength;

}

}

//启动子线程

fileSplitterFetch = new FileSplitterFetch[nStartPos.length];

for(int i=0;i<nStartPos.length;i++)

{

fileSplitterFetch[i] = new FileSplitterFetch(siteInfoBean.getSSiteURL(),

siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),

nStartPos[i],nEndPos[i],i);

Utility.log("Thread " + i + " , nStartPos = " + nStartPos[i] + ", nEndPos = " + nEndPos[i]);

fileSplitterFetch[i].start();

}

// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(),

siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1);

// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ",

nEndPos = " + nFileLength);

// fileSplitterFetch[nPos.length-1].start();

//等待子线程结束

//int count = 0;

//是否结束while循环

boolean breakWhile = false;

while(!bStop)

{

write_nPos();

Utility.sleep(500);

breakWhile = true;

for(int i=0;i<nStartPos.length;i++)

{

if(!fileSplitterFetch[i].bDownOver)

{

breakWhile = false;

break;

}

}

if(breakWhile)

break;

//count++;

//if(count4)

// siteStop();

}

System.err.println("文件下载结束!");

}

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

}

//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<nStartPos.length;i++)

{

// 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<nStartPos.length;i++)

{

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<nStartPos.length;i++)

fileSplitterFetch[i].splitterStop();

}

}

//负责部分文件的抓取

**FileSplitterFetch.java

*/

package NetFox;

import java.io.*;

import java.net.*;

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);//定位

}

public void run()

{

while(nStartPos < nEndPos && !bStop)

{

try{

URL url = new URL(sURL);

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

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

String sProperty = "bytes="+nStartPos+"-";

httpConnection.setRequestProperty("RANGE",sProperty);

Utility.log(sProperty);

InputStream input = httpConnection.getInputStream();

//logResponseHead(httpConnection);

byte[] b = new byte[1024];

int nRead;

while((nRead=input.read(b,0,1024)) 0 && nStartPos < nEndPos && !bStop)

{

nStartPos += fileAcces

 
 
 
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