multidownload.java

这是一个由本人编写的基于java编写的实现文件下载的应用程序

package download;
import java.util.*;
import java.io.*;
import java.lang.*;
import java.net.*;
public class MultiDownload {
boolean [] isStop;
Downloadsaction saction;
String url;
int byteCount;
long fileMark=0;
int threadNum;
boolean stopFlag;
DownloadGetFileLengh l=new DownloadGetFileLengh(); 


public void downProcess(String url,int byteCount,int threadNum)//start thread
{
	for(int i=0;i<threadNum;i++)
  {		int start=i*byteCount;
  		int end=byteCount*(i+1);
		File file=new File("temp_file_"+i+".temp");
		DownThread downThread=new DownThread(start,end,file,url,this,i);
		new Thread(downThread).start();
  }
  
	
}
public void uniteFile(int threadNum,File file) throws Exception
{  int i=0;
	while(i<threadNum)
	{File temp=new File("temp_file_" +i+".temp");
		FileInputStream in=new FileInputStream(temp);
	RandomAccessFile out=new RandomAccessFile(file,"rw");
	byte [] bytes=new byte[1024];
	int size=0;
	out.seek(fileMark);
	while((size=in.read(bytes,0,1024))>0)
	{
	out.write(bytes,0,size);
	fileMark=fileMark+(long)size;
	}
	i++;
	
	in.close();
	out.close();
	temp.delete();
	}
	
	
}

public void downMulitFile(List downList) throws Exception 
{
	for(int k=0;k<downList.size();k++)
	{
		Downloadsaction saction=(Downloadsaction)downList.get(k);
	int num=saction.getThreadNum();
	File file=saction.getFileName();
	String  url=saction.getURL();
	
	
	int length=l.getFileLength(url);
	if(length!=-1)
	{ 
		 final int byteNum=(int)length/num;
	    downProcess(url,byteNum,num);
	    isStop=new boolean[num];
	    boolean flag=l.allIsStop(isStop);
	    
	    if(flag)
	    {
	    	uniteFile(num,file);
	    }
	    
	
	}
	
	}
	}
	
}