AsyncTask异步通信工具

class PageTask extends AsyncTask<String, Integer, String> {
        // 可变长的输入参数，与AsyncTask.exucute()对应
        ProgressDialog pdialog;
        public PageTask(Context context){
            pdialog = new ProgressDialog(context, 0);   
            pdialog.setButton("cancel", new DialogInterface.OnClickListener() {
             public void onClick(DialogInterface dialog, int i) {
              dialog.cancel();
             }
            });
            pdialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
             public void onCancel(DialogInterface dialog) {
              finish();
             }
            });
            pdialog.setCancelable(true);
            pdialog.setMax(100);
            pdialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pdialog.show();


        }
        @Override
        protected String doInBackground(String... params) {

            try{

               HttpClient client = new DefaultHttpClient();
               // params[0]代表连接的url
               HttpGet get = new HttpGet(params[0]);
               HttpResponse response = client.execute(get);
               HttpEntity entity = response.getEntity();
               long length = entity.getContentLength();
               InputStream is = entity.getContent();
               String s = null;
               if(is != null) {
                   ByteArrayOutputStream baos = new ByteArrayOutputStream();

                   byte[] buf = new byte[128];

                   int ch = -1;

                   int count = 0;

                   while((ch = is.read(buf)) != -1) {

                      baos.write(buf, 0, ch);

                      count += ch;

                      if(length > 0) {
                          // 如果知道响应的长度，调用publishProgress（）更新进度
                          publishProgress((int) ((count / (float) length) * 100));
                      }

                      // 让线程休眠100ms
                      Thread.sleep(100);
                   }
                   s = new String(baos.toByteArray());              }
               // 返回结果
               return s;
            } catch(Exception e) {
               e.printStackTrace();

            }

            return null;

        }

        @Override
        protected void onCancelled() {
            super.onCancelled();
        }

        @Override
        protected void onPostExecute(String result) {
            // 返回HTML页面的内容
            message.setText(result);
            pdialog.dismiss(); 
        }

        @Override
        protected void onPreExecute() {
            // 任务启动，可以在这里显示一个对话框，这里简单处理
            message.setText(R.string.task_started);
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            // 更新进度
              System.out.println(""+values[0]);
              message.setText(""+values[0]);
              pdialog.setProgress(values[0]);
        }

     }

}