(android实战)AsycTask实现异步加载

1 实现效果说明:

1.1   加载题目信息之前,显示正在加载

 

1.2加载题目信息成功后,进行题目绑定

 

1.3加载不成功,转到加载失败

 

 

2 异步加载实现

2.1  界面设定

   加载前界面

 

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:background="#ffffff"
  android:orientation="horizontal"
  >
<ProgressBar   
        android:id="@+id/circleProgressBar"    
style="?android:attr/progressBarStyleLarge" mce_style="?android:attr/progressBarStyleLarge"  
 android:layout_width="wrap_content"   
android:layout_height="wrap_content"  
 android:visibility="gone"   
  android:max="100"
 android:progress="20"
      />  
  <TextView android:text="加载信息中。。。。。" 
            android:id="@+id/textView1" 
            android:layout_width="wrap_content" 
            android:textColor="#000000"
            android:layout_height="wrap_content"></TextView>
</LinearLayout>

   加载失败界面

 

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:background="#ffffff"
  android:orientation="horizontal"
  >
  <TextView android:text="网络异常,不能加载数据" android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView>
  <Button android:text="重新加载" android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button> 

</LinearLayout>

2.2 创建自定义异步类

 

//AsyncTask
    class AsyncLoader_GuessInfo extends AsyncTask<String, Void, Integer>{
      @Override
      protected Integer doInBackground(String... params) {
         int result=0;
    	  try{
    		  gi=GuessDataServiceHelper.GetGuessInfo(params[0]);
    		  result=2;
    	  }
         catch(Exception ex){
        	 result=-1; 
         }
    	  
        return result;
      } 
    }

 

 

2.3 调用异步类,并根据反馈结果进行显示不同的内容

 /*
     * 负责做下载题目信息
     * */
    private BegindownHandler mbegindownHandler = new BegindownHandler();
    
    class BegindownHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
             AsyncTask<String,Void, Integer>  results=   new AsyncLoader_GuessInfo().execute(GuessNo);
             try{
              if( results.get()==2)
                {
                  LoadAndBandingData(GuessNo);
                }
              else
                  setContentView(R.layout.async_error);
             }
             catch(Exception ex)
             {
                 setContentView(R.layout.async_error);
                 
             }
            
        }
        public void sleep(long delayMillis) {
            this.removeMessages(0);
            sendMessageDelayed(obtainMessage(0), delayMillis);
        }
    };