filesplitterfetch.java

实现java断点续传多线程处理原代码,三种形式下载,

package com.download;

import java.io.*;
import java.net.*;

/**
 * 负责部分文件的抓取。 
 * @author yeqc	
 * 2008-06-28
 */
public class FileSplitterFetch extends Thread {
	
	/**
	 * 文件路径
	 */
	String sURL; //File URL
	
	/**
	 * 开始的指针定位
	 */
	long nStartPos; 
	
	/**
	 * 结束的指针定位
	 */
	long nEndPos; 
	
	/**
	 * 线程id
	 */
	int nThreadID; 
	
	/**
	 * 是否下载结束
	 */
	boolean bDownOver = false; 
	
	/**
	 * 
	 */
	boolean bStop = false; 
	
	/**
	 * 文件访问接口
	 */
	FileAccessI fileAccessI = null; 
	
	
	public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int did) throws IOException
	{
		this.sURL = sURL;
		this.nStartPos = nStart;
		this.nEndPos = nEnd;
		nThreadID = did;
		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");
		String sProperty = "bytes="+nStartPos+"-";
		httpConnection.setRequestProperty("RANGE",sProperty);
		InputStream input = httpConnection.getInputStream();

		byte[] b = new byte[1024];
		int nRead;
		while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos 
		&& !bStop){
			nStartPos += fileAccessI.write(b,0,nRead);
	
		}
	
		bDownOver = true;
		System.out.println("--fileAccessI.write (b,0,nRead);--- ");
		fileAccessI.write (b,0,nRead);
		}
	catch(Exception e){
		e.printStackTrace ();
		
			}
		}
	
	}
	
	
	//打印回应的头信息
	public void logResponseHead(HttpURLConnection con)
	{
	for(int i=1;;i++)
	{
		String header=con.getHeaderFieldKey(i);
		if(header!=null)
			System.out.println(header+" : "+con.getHeaderField(header));
		else
			break;
		}
	
	}
	
	
	public void splitterStop()
	{
		bStop = true;
	}

}