下载进度条

<?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"
/>
</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);
	}	 
 
 
}

源代码：
Android DownloadFile (1966)