<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:orientation="vertical"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     > <TextView  android:id="@+id/tv"     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:text=""     /> <ProgressBar android:id="@+id/down_pb"  android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:max="100"     style="?android:attr/progressBarStyleHorizontal" mce_style="?android:attr/progressBarStyleHorizontal" /> </LinearLayout>

package com.pocketdigi.download; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.URL; import java.net.URLConnection; import org.apache.http.client.ClientProtocolException; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.util.Log; import android.widget.ProgressBar; import android.widget.TextView; import android.widget.Toast; public class main extends Activity {     /** Called when the activity is first created. */  ProgressBar pb;  TextView tv;  int   fileSize;  int   downLoadFileSize;  String fileEx,fileNa,filename;  private Handler handler = new Handler()    {      @Override      public void handleMessage(Message msg)      {//定义一个Handler，用于处理下载线程与UI间通讯        if (!Thread.currentThread().isInterrupted())        {          switch (msg.what)          {            case 0:              pb.setMax(fileSize);            case 1:              pb.setProgress(downLoadFileSize);              int result = downLoadFileSize * 100 / fileSize;              tv.setText(result + "%");              break;            case 2:              Toast.makeText(main.this, "文件下载完成", 1).show();              break;            case -1:              String error = msg.getData().getString("error");              Toast.makeText(main.this, error, 1).show();              break;          }        }        super.handleMessage(msg);      }    };     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);         pb=(ProgressBar)findViewById(R.id.down_pb);         tv=(TextView)findViewById(R.id.tv);         new Thread(){          public void run(){           try {      down_file("http://wallpaper.pocketdigi.com/upload/1/bigImage/1284565196.jpg","/sdcard/");      //下载文件，参数：第一个URL，第二个存放路径     } catch (ClientProtocolException e) {      // TODO Auto-generated catch block      e.printStackTrace();     } catch (IOException e) {      // TODO Auto-generated catch block      e.printStackTrace();     }          }         }.start();     }     public void down_file(String url,String path) throws IOException{      //下载函数          filename=url.substring(url.lastIndexOf("/") + 1);      //获取文件名      URL myURL = new URL(url);      URLConnection conn = myURL.openConnection();      conn.connect();      InputStream is = conn.getInputStream();      this.fileSize = conn.getContentLength();//根据响应获取文件大小      if (this.fileSize <= 0) throw new RuntimeException("无法获知文件大小 ");      if (is == null) throw new RuntimeException("stream is null");      FileOutputStream fos = new FileOutputStream(path+filename);      //把数据存入路径+文件名      byte buf[] = new byte[1024];      downLoadFileSize = 0;      sendMsg(0);      do        {       //循环读取          int numread = is.read(buf);          if (numread == -1)          {            break;          }          fos.write(buf, 0, numread);          downLoadFileSize += numread;          sendMsg(1);//更新进度条        } while (true);      sendMsg(2);//通知下载完成      try        {          is.close();        } catch (Exception ex)        {          Log.e("tag", "error: " + ex.getMessage(), ex);        }     }  private void sendMsg(int flag)  {      Message msg = new Message();      msg.what = flag;      handler.sendMessage(msg);  }  }