Android 下载文件 显示进度条

加入两个权限

一个是联网，另一个是读写SD卡

 <uses-permission android:name="android.permission.INTERNET"></uses-permission>   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

下载地址是本人的另外一台主机，现在当服务器了，路径可以测试

http://210.30.12.1:8080/mp3/DJ.mp3

import java.io.File;  import java.io.FileNotFoundException;  import java.io.FileOutputStream;  import java.io.IOException;  import java.io.InputStream;  import java.io.OutputStream;  import java.io.RandomAccessFile;  import java.net.MalformedURLException;  import java.net.URL;  import java.net.URLConnection;    import android.app.Activity;  import android.os.Bundle;  import android.os.Environment;  import android.os.Handler;  import android.os.Message;  import android.util.Log;  import android.view.View;  import android.view.View.OnClickListener;  import android.widget.Button;  import android.widget.ProgressBar;  import android.widget.TextView;  import android.widget.Toast;    public class FileDownProcessBarActivity extends Activity {      /** Called when the activity is first created. */   private static final String Path="http://210.30.12.1:8080/mp3/DJ.mp3";   private ProgressBar progressBar;   private TextView textView;   private Button button;   private int FileLength;   private int DownedFileLength=0;   private InputStream inputStream;   private URLConnection connection;   private OutputStream outputStream;      @Override      public void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.main);          progressBar=(ProgressBar) findViewById(R.id.progressBar1);          textView=(TextView) findViewById(R.id.textView2);          button=(Button) findViewById(R.id.button1);          button.setOnClickListener(new ButtonListener());      }      class ButtonListener implements OnClickListener{      @Override    public void onClick(View v) {     DownedFileLength=0;     // TODO Auto-generated method stub       Thread thread=new Thread(){      public void run(){       try {       DownFile(Path);      } catch (Exception e) {       // TODO: handle exception      }      }       };       thread.start();    }       }      private Handler handler=new Handler()      {        public void handleMessage(Message msg)        {    if (!Thread.currentThread().isInterrupted()) {     switch (msg.what) {     case 0:      progressBar.setMax(FileLength);      Log.i("文件长度----------->", progressBar.getMax()+"");       break;     case 1:      progressBar.setProgress(DownedFileLength);      int x=DownedFileLength*100/FileLength;      textView.setText(x+"%");      break;     case 2:      Toast.makeText(getApplicationContext(), "下载完成", Toast.LENGTH_LONG).show();      break;           default:      break;     }    }     }              };     private void DownFile(String urlString)      {           /*     * 连接到服务器     */           try {      URL url=new URL(urlString);      connection=url.openConnection();      if (connection.getReadTimeout()==5) {      Log.i("---------->", "当前网络有问题");      // return;        }      inputStream=connection.getInputStream();         } catch (MalformedURLException e1) {     // TODO Auto-generated catch block     e1.printStackTrace();    } catch (IOException e) {     // TODO Auto-generated catch block     e.printStackTrace();    }        /*     * 文件的保存路径和和文件名其中Nobody.mp3是在手机SD卡上要保存的路径，如果不存在则新建     */    String savePAth=Environment.getExternalStorageDirectory()+"/DownFile";    File file1=new File(savePAth);    if (!file1.exists()) {        file1.mkdir();    }    String savePathString=Environment.getExternalStorageDirectory()+"/DownFile/"+"DJ.mp3";    File file =new File(savePathString);    if (!file.exists()) {     try {      file.createNewFile();     } catch (IOException e) {      // TODO Auto-generated catch block      e.printStackTrace();     }     }    /*     * 向SD卡中写入文件,用Handle传递线程     */    Message message=new Message();    try {     outputStream=new FileOutputStream(file);     byte [] buffer=new byte[1024*4];     FileLength=connection.getContentLength();     message.what=0;     handler.sendMessage(message);     while (DownedFileLength<FileLength) {      outputStream.write(buffer);         DownedFileLength+=inputStream.read(buffer);         Log.i("-------->", DownedFileLength+"");         Message message1=new Message();         message1.what=1;         handler.sendMessage(message1);     }     Message message2=new Message();     message2.what=2;     handler.sendMessage(message2);    } catch (FileNotFoundException e) {     // TODO Auto-generated catch block     e.printStackTrace();    } catch (IOException e) {     // TODO Auto-generated catch block     e.printStackTrace();    }      }          }