Android的Eclipse中的AsyncTask - 但結果是空的 - 有人可以看看

Question

遺憾的是一種痛苦，但我一直在這一個時間過長，我相信這是一個簡單的人，但我累了，不能看它。所有工作正常，但在「字符串結果」爲空

package com.example.me; 

import java.util.ArrayList; 

import org.apache.http.NameValuePair; 
import org.apache.http.message.BasicNameValuePair; 

import android.os.AsyncTask; 
import android.os.Bundle; 
import android.app.Activity; 
import android.widget.Button; 
import android.widget.TextView; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 

public class MainActivity extends Activity { 

    Button btnLoginButton; 
    TextView tmpError, tmpUsername, tmpPassword; 
    ArrayList<NameValuePair> postParameters; 
    String response; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     tmpError = (TextView) findViewById(R.id.lblMessage); 
     tmpUsername = (TextView) findViewById(R.id.txtUsername); 
     tmpPassword = (TextView) findViewById(R.id.txtPassword); 

     addListenerOnButton(); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.activity_main, menu); 
     return true; 
    } 

    public void addListenerOnButton() { 

     btnLoginButton = (Button) findViewById(R.id.btnLogin); 
     btnLoginButton.setOnClickListener(new OnClickListener() { 
      public void onClick(View arg) { 
       try{ 
        triggerClick(); 
       } 
       catch (Exception e) {   
        tmpError.setText("[]" + e.toString()); 
       } 
      } 
     }); 
    } 

    private void triggerClick() { 

     postParameters = new ArrayList<NameValuePair>(); 
     postParameters.add(new BasicNameValuePair("username", tmpUsername.getText().toString())); 
     postParameters.add(new BasicNameValuePair("password", tmpPassword.getText().toString())); 

     final class HttpTask 
       extends 
       AsyncTask<String/* Param */, Boolean /* Progress */, String /* Result */> { 

      @Override 
      protected String doInBackground(String... params) { 
       publishProgress(true); 
       try { 
       response = CustomHttpClient.executeHttpPost("http://some.url/thatiknoworks/check.php", postParameters); 
          return response; 
       } catch (Exception e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
       }  

      } 

      @Override 
      protected void onPostExecute(String result) { 
       publishProgress(false); 

       result = result.replaceAll("\\s+",""); 

       if(result.equals("1")) { 
        tmpError.setText("Correct"); 
       } 
       else { 
        tmpError.setText("Sorry!!("+result+")"); 
       } 
      } 

     }  

     new HttpTask().execute(); 
    } 
} 

因爲在doInBackground()返回空字符串，你應該做一個空的「結果」的字符串:-(

Answer 1

回來一次又一次：

protected String doInBackground(String... params) { 
      publishProgress(true); 
      try { 
       return CustomHttpClient.executeHttpPost("http://some.url/thatiknoworks/check.php", postParameters); 
      } catch (Exception e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
       return ""; 
      }  

     } 

Answer 2

字符串的結果，因爲你是從返回的doInBackground()空字符串爲空

return ""; 

。

Answer 3

請聲明String response;作爲一個全局變量。

protected String doInBackground(String... params) 
{ 
    publishProgress(true); 
    try 
    { 
    response=CustomHttpClient.executeHttpPost("http://some.url/thatiknoworks/check.php", postParameters); 
    return response; 
    } 
    catch (Exception e) 
    { 
     e.printStackTrace(); 
    }  
}