Java实现断点续传(HTTP)代码,Python代码库,德仔网

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【Python】 Java实现断点续传(HTTP)
作者:Lucien / 发布于2014/10/10/ 920

	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
	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(count>4)
	// 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();
	}
	}
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