Android 一个下载任务分为多个线程下载

[java] view plain copy print ?

packagemy.Thread;
importjava.io.BufferedInputStream;
importjava.io.RandomAccessFile;
importjava.net.HttpURLConnection;
importjava.net.URL;
importjava.net.URLConnection;
importjava.util.concurrent.CountDownLatch;
importandroid.app.Activity;
importandroid.os.Bundle;
importandroid.os.Environment;
importandroid.view.View;
importandroid.view.View.OnClickListener;
importandroid.widget.Button;
importandroid.widget.TextView;
publicclassManyThreadActivityextendsActivity{
/**Calledwhentheactivityisfirstcreated.*/
privateButtonbutton;
privateTextViewtextView;
privatestaticfinalintTHREAD_COUNT=4;
privateCountDownLatchlatch=newCountDownLatch(THREAD_COUNT);
privatelongcompleteLength=0;
privatelongfileLength;
publicstaticStringSaveFile=Environment.getExternalStorageDirectory()+"/DownFile/"+"test.Mp3";
publicstaticfinalStringurl="http://210.30.12.33:8080/mp3/Beyond.mp3";
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
button=(Button)findViewById(R.id.button1);
textView=(TextView)findViewById(R.id.editText1);
textView.setText(url);
button.setOnClickListener(newMyListener());
}
classMyListenerimplementsOnClickListener{
@Override
publicvoidonClick(Viewv){
//TODOAuto-generatedmethodstub
try{
download(url);
}catch(Exceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
}
}
//进行下载的线程
classDownloadThreadextendsThread{
privateURLurl;
privateRandomAccessFilefile;
privatelongfrom;
privatelongend;
/**
*@paramurl下载的URL
*@paramfile下载完成之后存储的文件
*@paramfrom当前线程对应文件的起始位置
*@paramend当前线程对应文件的结束位置
*/
DownloadThread(URLurl,RandomAccessFilefile,longfrom,longend){
this.url=url;
this.file=file;
this.from=from;
this.end=end;
}
publicvoidrun(){
try{
longpos=from;
byte[]buf=newbyte[1024*8];
HttpURLConnectioncn=(HttpURLConnection)url.openConnection();
//设置请求的起始和结束位置。
cn.setRequestProperty("Range","bytes="+from+"-"+end);
BufferedInputStreambis=newBufferedInputStream(cn.getInputStream());
intlen;
while((len=bis.read(buf))>0){
synchronized(file){
file.seek(pos);
file.write(buf,0,len);
}
pos+=len;
completeLength+=len;
System.out.println(completeLength*100/fileLength+"%");
}
cn.disconnect();
}catch(Exceptione){
e.printStackTrace();
}
latch.countDown();
}
}
publicvoiddownload(Stringaddress)throwsException{
URLurl=newURL(address);
URLConnectioncn=url.openConnection();
fileLength=cn.getContentLength();
longpackageLength=fileLength/THREAD_COUNT;//每个线程要下载的字节数
longleftLength=fileLength%THREAD_COUNT;//剩下的字节数
RandomAccessFilefile=newRandomAccessFile(SaveFile,"rw");
System.out.println(fileLength);
//计算每个线程请求的起始位置和结束位置。
/*
*第一个线程的起始位置是0~0+packageLength(每个线程要下载的字节数)
*第二个线程的起始位置是endPos+1(第一个线程的packageLength+1)~endPos+1+packageLength
*第二个线程的起始位置是.........
*/
longpos=0;
for(inti=0;i<THREAD_COUNT;i++){
longendPos=pos+packageLength;
newDownloadThread(url,file,pos,endPos).start();
if(leftLength>0){
endPos++;
leftLength--;
}
pos=endPos;
}
latch.await();
}
}

Android 一个下载任务分为多个线程下载_第1张图片

保存为test.mp3文件

Android 一个下载任务分为多个线程下载_第2张图片

本文出自:http://blog.csdn.net/rwyz1314/article/details/6919596

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