Android文件下载进度条的实现

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1. <?xml version="1.0" encoding="utf-8"?>    
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    
3.     android:orientation="vertical"    
4.     android:layout_width="fill_parent"    
5.     android:layout_height="fill_parent"    
6.     >    
7. <TextView  android:id="@+id/tv"    
8.     android:layout_width="fill_parent"     
9.     android:layout_height="wrap_content"     
10.     android:text=""    
11.     />    
12. <ProgressBar android:id="@+id/down_pb"    
13.     android:layout_width="fill_parent"     
14.     android:layout_height="wrap_content"    
15.     android:max="100"    
16.     style="?android:attr/progressBarStyleHorizontal" mce_style="?android:attr/progressBarStyleHorizontal"    
17. />    
18. </LinearLayout>   

main.java:

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1. package com.pocketdigi.download;    
2.      
3. import java.io.FileOutputStream;    
4. import java.io.IOException;    
5. import java.io.InputStream;    
6. import java.net.URL;    
7. import java.net.URLConnection;    
8.      
9. import org.apache.http.client.ClientProtocolException;    
10. import android.app.Activity;    
11. import android.os.Bundle;    
12. import android.os.Handler;    
13. import android.os.Message;    
14. import android.util.Log;    
15. import android.widget.ProgressBar;    
16. import android.widget.TextView;    
17. import android.widget.Toast;    
18.      
19. public class main extends Activity {    
20.     /** Called when the activity is first created. */    
21.     ProgressBar pb;    
22.     TextView tv;    
23.     int   fileSize;    
24.     int   downLoadFileSize;    
25.     String fileEx,fileNa,filename;    
26.     private Handler handler = new Handler()    
27.       {    
28.         @Override    
29.         public void handleMessage(Message msg)    
30.         {//定义一个Handler，用于处理下载线程与UI间通讯    
31.           if (!Thread.currentThread().isInterrupted())    
32.           {    
33.             switch (msg.what)    
34.             {    
35.               case 0:    
36.                 pb.setMax(fileSize);    
37.               case 1:    
38.                 pb.setProgress(downLoadFileSize);    
39.                 int result = downLoadFileSize * 100 / fileSize;    
40.                 tv.setText(result + "%");    
41.                 break;    
42.               case 2:    
43.                 Toast.makeText(main.this, "文件下载完成", 1).show();    
44.                 break;    
45.      
46.               case -1:    
47.                 String error = msg.getData().getString("error");    
48.                 Toast.makeText(main.this, error, 1).show();    
49.                 break;    
50.             }    
51.           }    
52.           super.handleMessage(msg);    
53.         }    
54.       };    
55.     @Override    
56.     public void onCreate(Bundle savedInstanceState) {    
57.         super.onCreate(savedInstanceState);    
58.         setContentView(R.layout.main);    
59.         pb=(ProgressBar)findViewById(R.id.down_pb);    
60.         tv=(TextView)findViewById(R.id.tv);    
61.         new Thread(){    
62.             public void run(){    
63.                 try {    
64.        down_file("http://wallpaper.pocketdigi.com/upload/1/bigImage/1284565196.jpg",  
65. "/sdcard/");    
66.                     //下载文件，参数：第一个URL，第二个存放路径    
67.                 } catch (ClientProtocolException e) {    
68.                     // TODO Auto-generated catch block    
69.                     e.printStackTrace();    
70.                 } catch (IOException e) {    
71.                     // TODO Auto-generated catch block    
72.                     e.printStackTrace();    
73.                 }    
74.             }    
75.         }.start();    
76.      
77.      
78.     }    
79.     public void down_file(String url,String path) throws IOException{    
80.         //下载函数          
81.         filename=url.substring(url.lastIndexOf("/") + 1);    
82.         //获取文件名    
83.         URL myURL = new URL(url);    
84.         URLConnection conn = myURL.openConnection();    
85.         conn.connect();    
86.         InputStream is = conn.getInputStream();    
87.         this.fileSize = conn.getContentLength();//根据响应获取文件大小    
88.         if (this.fileSize <= 0) throw new RuntimeException("无法获知文件大小 ");    
89.         if (is == null) throw new RuntimeException("stream is null");    
90.         FileOutputStream fos = new FileOutputStream(path+filename);    
91.         //把数据存入路径+文件名    
92.         byte buf[] = new byte[1024];    
93.         downLoadFileSize = 0;    
94.         sendMsg(0);    
95.         do    
96.           {    
97.             //循环读取    
98.             int numread = is.read(buf);    
99.             if (numread == -1)    
100.             {    
101.               break;    
102.             }    
103.             fos.write(buf, 0, numread);    
104.             downLoadFileSize += numread;    
105.      
106.             sendMsg(1);//更新进度条    
107.           } while (true);    
108.         sendMsg(2);//通知下载完成    
109.         try    
110.           {    
111.             is.close();    
112.           } catch (Exception ex)    
113.           {    
114.             Log.e("tag", "error: " + ex.getMessage(), ex);    
115.           }    
116.      
117.     }    
118.     private void sendMsg(int flag)    
119.     {    
120.         Message msg = new Message();    
121.         msg.what = flag;    
122.         handler.sendMessage(msg);    
123.     }        
124.      
125.      
126. }