Android multi-thread download

 

Package my. Thread;

 

Import java. io. BufferedInputStream;

Import java. io. RandomAccessFile;

Import java.net. HttpURLConnection;

Import java.net. URL;

Import java.net. URLConnection;

Import java. util. concurrent. CountDownLatch;

 

 

Import android. app. Activity;

Import android. OS. Bundle;

Import android. OS. Environment;

Import android. view. View;

Import android. view. View. OnClickListener;

Import android. widget. Button;

Import android. widget. TextView;

 

Public class ManyThreadActivity extends Activity {

/** Called when the activity is first created .*/

Private Button button;

Private TextView textView;

Private static final int THREAD_COUNT = 4;

Private CountDownLatch latch = new CountDownLatch (THREAD_COUNT );

Private long completeLength = 0;

Private long fileLength;

Public static String SaveFile = Environment. getExternalStorageDirectory () + "/DownFile/" + "test. Mp3 ";

Public static final String url = "http: // 210.30.12.33: 8080/mp3/Beyond.mp3 ";

@ Override

Public void onCreate (Bundle savedInstanceState ){

Super. onCreate (savedInstanceState );

SetContentView (R. layout. main );

Button = (Button) findViewById (R. id. button1 );

TextView = (TextView) findViewById (R. id. editText1 );

TextView. setText (url );

Button. setOnClickListener (new MyListener ());

}

Class MyListener implements OnClickListener {

 

@ Override

Public void onClick (View v ){

// TODO Auto-generated method stub

Try {

Download (url );

} Catch (Exception e ){

// TODO Auto-generated catch block

E. printStackTrace ();

}

}

}

 

// Download thread

Class DownloadThread extends Thread {

Private URL;

Private RandomAccessFile file;

Private long from;

Private long end;

 

/**

* @ Param url: the download URL.

* @ Param file the file stored after the download is complete

* @ Param from start position of the file corresponding to the current thread

* @ Param end the end position of the file corresponding to the current thread

*/

DownloadThread (URL url, RandomAccessFile file, long from, long end ){

This. url = url;

This. file = file;

This. from = from;

This. end = end;

}

 

Public void run (){

Try {

Long pos = from;

Byte [] buf = new byte [1024*8];

 

HttpURLConnection cn = (HttpURLConnection) url. openConnection ();

// Set the start position and end position of the request.

Cn. setRequestProperty ("Range", "bytes =" + from + "-" + end );

 

BufferedInputStream bis = new BufferedInputStream (cn. getInputStream ());

Int len;

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 (Exception e ){

E. printStackTrace ();

}

Latch. countDown ();

}

}

 

Public void download (String address) throws Exception {

URL url = new URL (address );

URLConnection cn = url. openConnection ();

FileLength = cn. getContentLength ();

Long packageLength = fileLength/THREAD_COUNT; // The number of bytes to be downloaded by each thread

Long leftLength = fileLength % THREAD_COUNT; // remaining bytes

RandomAccessFile file = new RandomAccessFile (SaveFile, "rw ");

System. out. println (fileLength );

// Calculate the start position and end position of each thread request.

/*

* The starting position of the first thread is 0 ~ 0 + packageLength (number of bytes to be downloaded by each thread)

* The starting position of the second thread is endPos + 1 (packageLength + 1 of the first thread )~ EndPos + 1 + packageLength

* The starting position of the second thread is .........

*/

Long pos = 0;

For (int I = 0; I <THREAD_COUNT; I ++ ){

Long endPos = pos + packageLength;

New DownloadThread (url, file, pos, endPos). start ();

If (leftLength> 0 ){

EndPos ++;

LeftLength --;

}

Pos = endPos;

}

Latch. await ();

}

 

}

 

Save as testbench File

 

From Viagra ~ YZ