Question

对于此代码段（我排除了doInBackground(), postExecute()等）从CheckServer活动调用异步任务时，我应该如何传递Activity参数？

public class CheckServer  extends Activity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);


    HttpTicket ticket= new HttpTicket(); //HOW IS THIS LINE DONE? WHAT PARAM SHOULD BE PASSED?



    }

    @SuppressWarnings("unused")
    private class HttpTicket extends AsyncTask<String, String, String>
    {
        private Activity activity;
        private ProgressDialog dialog;

         public HttpTicket(Activity activity) {

            this.activity = activity;


        }

Answer 1

在你的活动onCreate（）

中

 HttpTicket ticket= new HttpTicket(Activity.this);
 //passing context to the asynctask constructor
 ticket.execute();
 //call execute to laod asynctask

将asynctask定义如下

private class HttpTicket extends AsyncTask<String, String, String>
{
    private Activity activity;
    private ProgressDialog dialog;

     public HttpTicket(Activity activity) {

        this.activity = activity;
        dialog = new ProgressDialog(activity);
        dialog.setTitle("Wait...");
    }
   protected void onPreExecute()
   {
      dialog.show();
   }
   protected String doInBackground(String params)
   {  
      //background opearation

     return "string";
   }
   protected void onPostExecute(String result)
   {
       dialog.dismiss();
       //update ui
   }


  }

Answer 2

你可以狡猾地做

HttpTicket mHttpTicket = new HttpTicket(this); 
mHttpTicket.execute();

您也可以删除构造函数，然后将其作为参数传递给OnPreExecute。然后你在execute(this);

中给出它

从Activity调用AsyncTask

2 个答案: