Android学习之多线程开发总结<三>

 1     private void connect() {  
 2         MyTask task = new MyTask(this);  
 3         task.execute(url.getText().toString());  
 4     }    
 5     
 6     private class MyTask extends AsyncTask<String, Integer, String> {  
 7         private Context ctx;
 8         private ProgressDialog pdialog;
 9         public MyTask(Context ctx){
10             super();
11             this.ctx = ctx;
12             //创建ProgressDialog
13             pdialog = new ProgressDialog(ctx, 0);     
14             pdialog.setButton("cancel", new DialogInterface.OnClickListener() {  
15                 public void onClick(DialogInterface dialog, int i) {  
16                     //dialog.cancel();  
17                 }  
18             });  
19             pdialog.setOnCancelListener(new DialogInterface.OnCancelListener() {  
20                 public void onCancel(DialogInterface dialog) {  
21                     finish();  
22                 }  
23             });  
24             pdialog.setCancelable(true);  
25             pdialog.setMax(100);  
26             pdialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);  
27             pdialog.show();  
28         }
29     
30         //onPreExecute方法用于在执行后台任务前做一些UI操作  
31         @Override  
32         protected void onPreExecute() {  
33             Log.i(TAG, "onPreExecute() called");  
34             //textView.setText("loading...");  
35         }  
36           
37         //doInBackground方法内部执行后台任务,不可在此方法内修改UI  
38         @Override  
39         protected String doInBackground(String... params) {  
40             Log.i(TAG, "doInBackground(Params... params) called");  
41             try {  
42                 HttpClient client = new DefaultHttpClient();  
43                 HttpGet get = new HttpGet(params[0]);  
44                 HttpResponse response = client.execute(get);  
45                 if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {  
46                     HttpEntity entity = response.getEntity();  
47                     InputStream is = entity.getContent();  
48                     long total = entity.getContentLength();  
49                     ByteArrayOutputStream baos = new ByteArrayOutputStream();  
50                     byte[] buf = new byte[1024];  
51                     int count = 0;  
52                     int length = -1;  
53                     while ((length = is.read(buf)) != -1) {  
54                         baos.write(buf, 0, length);  
55                         count += length;  
56                         //调用publishProgress公布进度,最后onProgressUpdate方法将被执行  
57                         publishProgress((int) ((count / (float) total) * 100));  
58                         //为了演示进度,休眠500毫秒  
59                         Thread.sleep(500);  
60                     }  
61                     return new String(baos.toByteArray(), "gb2312");  
62                 }  
63             } catch (Exception e) {  
64                 Log.e(TAG, e.getMessage());  
65             }  
66             return null;  
67         }  
68           
69         //onProgressUpdate方法用于更新进度信息  
70         @Override  
71         protected void onProgressUpdate(Integer... values) {  
72             Log.i(TAG, "onProgressUpdate(Progress... values) called");  
73             //pdialog.setProgress(values[0]);
74             //textView.setText("loading..." + values[0] + "%");  
75         }  
76           
77         //onPostExecute方法用于在执行完后台任务后更新UI,显示结果  
78         @Override  
79         protected void onPostExecute(String result) {  
80             Log.i(TAG, "onPostExecute(Result result) called");  
81             //pdialog.dismiss();  
82             //textView.setText(result);   
83         }  
84           
85         //onCancelled方法用于在取消执行中的任务时更改UI  
86         @Override  
87         protected void onCancelled() {  
88             super.onCancelled();  
89             Log.i(TAG, "onCancelled() called");  
90             //textView.setText("cancelled");  
91         }  
92     }