lownloadfilethread.java

java多线程下载(程序源码) 只具备简单功能

import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;

import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JTextArea;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class LownLoadFileThread extends Thread{
private JProgressBar jProgressBar;
String URL;
    long startPos;
    long endPos;
    int threadID;
    JTextArea textArea=new JTextArea();
    RandomAccessFile file;
    private int readPos = 0;
    private int in = 0;
    public LownLoadFileThread(String URL,long startPos,long endPos,int id,JTextArea textArea
       ,JProgressBar jProgressBar,String saveURL)throws IOException{
    this.jProgressBar = jProgressBar;
    this.URL = URL;
    this.startPos = startPos;
    this.endPos = endPos;
    this.threadID = id;
    this.textArea = textArea;
        file=new RandomAccessFile(saveURL,"rw");
        file.seek(startPos);
    }
    public void run(){
    //DownLoad download = new DownLoad();
    try{
    URL url = new URL(URL);
    HttpURLConnection httpConnection=(HttpURLConnection)url.openConnection();
    String sProperty="bytes="+startPos+"-";
    httpConnection.setRequestProperty("RANGE",sProperty);
       // System.out.println("线程"+threadID+"下载文件、、、请等待");
        textArea.append("\n 线程"+threadID+"下载文件、、、请等待");
        InputStream input=httpConnection.getInputStream();
        byte[] buf=new byte[1024];
        int offset;
        offset=(int)endPos-(int)startPos;
        if(offset>1024)
            offset=1024;
        while((in = input.read(buf,0,offset))>0 && startPos<endPos) 
        {   if(((int) endPos - (int) startPos)<1024)
       in = (int) endPos - (int) startPos;
        /*if(in<1024){
        System.out.println("in is :"+in+" -- startpos is "+startPos);
        }*/
        readPos +=in;
        //System.out.println("已读取"+in+"个字节。");
        textArea.append("\n 线程"+threadID+" 已读取"+readPos+"个字节, start is :"+startPos+" and end is:"+endPos+"。");
            offset = (int) endPos - (int) startPos;
            if (offset > 1024)
                offset = 1024;
         //   System.out.println("threadID: "+threadID+" started: "+startPos+" offset: "+offset);
            file.write(buf,0,in);
            startPos+=in;
            
        }
      // System.out.println("线程"+threadID+"下载完毕！！");

        textArea.append("\n 线程"+threadID+"下载完毕！！");
        file.close();
        input.close();
    }catch(Exception ex){
      
    }
    }
public int getReadPos() {
   return readPos;
}
public void setReadPos(int readPos) {
   this.readPos = readPos;
}
    
}