从 Activity 调用 AsyncTask答案

【问题标题】：Calling AsyncTask from the Activity从 Activity 调用 AsyncTask
【发布时间】：2013-04-05 08:34:58
【问题描述】：

对于这个代码sn-p（我已经排除了doInBackground(), postExecute()等）从 CheckServer Activity 调用 Async Task 时应该如何传递 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;


        }

【问题讨论】：

创建构造函数HttpTicket（Activity）。 HttpTicket 票=新的 HttpTicket(Activity.this); ticket.execute();

标签： android asynchronous

【解决方案1】：

你可以简单地做

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

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

【讨论】：

【解决方案2】：

在你的活动中 onCreate()

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

如下定义异步任务

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
   }


  }

【讨论】：