Android更新下载进度条

下载文件会阻塞UI主线程，所以需要new一个新线程来执行下载操作，通过handler执行更新UI进度条操作。代码如下：

[java] view plain copy print ?

1. public class AndroidTest extends Activity { 
2.     private static final String TAG = "AndroidTest"; 
3.  
4.     private ProgressBar progressBar = null; 
5.     private Button startButton = null; 
6.     private EditText filenameText = null; 
7.     private MyHandler handler = null; 
8.  
9.     private Message message = null; 
10.     private boolean flag = true; 
11.     private int size = 1; 
12.     private int hasRead = 0; 
13.     private int len = 0; 
14.     private byte buffer[] = new byte[1024*4]; 
15.     private int index = 0;  
16.      
17.     @Override 
18.     public void onCreate(Bundle savedInstanceState) { 
19.     super.onCreate(savedInstanceState); 
20.         setContentView(R.layout.main); 
21.          
22.         progressBar = (ProgressBar)findViewById(R.id.progress_horizontal); 
23.         startButton = (Button)findViewById(R.id.mybutton); 
24.         startButton.setOnClickListener(new ButtonClick()); 
25.      
26.         filenameText = (EditText)findViewById(R.id.fileNameID); 
27.      
28.         handler = new MyHandler(); 
29.     } 
30.  
31.  
32.     public boolean downloadFile(final String urlStr, final String filename) { 
33.         new Thread(new Runnable(){   
34.             public void run() {  
35.                 try { 
36.                     URL url = new URL(urlStr); 
37.                     HttpURLConnection connection = (HttpURLConnection)url.openConnection(); 
38.                     size = connection.getContentLength(); 
39.                     InputStream inputStream = connection.getInputStream(); 
40.                     OutputStream outputStream = new FileOutputStream(Environment.getExternalStorageDirectory()+"/"+filename); 
41.                      
42.                     while((len=inputStream.read(buffer))!=-1){ 
43.                         outputStream.write(buffer); 
44.                         hasRead+=len; 
45.                         index = (int)(hasRead*100)/size; 
46.                         message = new Message(); 
47.                         message.what = 1; 
48.                         handler.sendMessage(message); 
49.                         Log.d(TAG, "index = " + index); 
50.                         System.out.println("has = "+hasRead+" size = "+size+" index = "+index); 
51.                     } 
52.                  
53.                     inputStream.close(); 
54.                     outputStream.close(); 
55.                 } catch (Exception e) { 
56.                     flag = false; 
57.                     e.printStackTrace(); 
58.                 } 
59.             } 
60.         }).start(); 
61.          
62.         return flag; 
63.     } 
64.  
65.     class ButtonClick implements OnClickListener { 
66.  
67.         public void onClick(View v) { 
68.      
69.             String url = filenameText.getText().toString(); 
70.             String filename = url.substring(url.lastIndexOf('/') + 1); 
71.             Log.d(TAG, "url = " + url); 
72.             Log.d(TAG, "filename = " + filename); 
73.              
74.             if(!downloadFile(url, filename)) { 
75.                 String rs = "下载失败 "; 
76.                 Toast.makeText(AndroidTest.this, rs, Toast.LENGTH_SHORT).show(); 
77.             } 
78.      
79.         } 
80.  
81.     } 
82.  
83.     class MyHandler extends Handler{ 
84.  
85.         @Override 
86.         public void handleMessage(Message msg) { 
87.             if (msg.what == 1) { 
88.                 progressBar.setProgress(index); 
89.                 Log.d(TAG, "setProgress index:" + index); 
90.                 if (index >= 99) { 
91.                     String rs = "下载完成"; 
92.                     Toast.makeText(AndroidTest.this, rs, Toast.LENGTH_SHORT).show(); 
93.                 } 
94.             } 
95.              
96.             super.handleMessage(msg); 
97.         } 
98.  
99.     } 
100.  
101. }