客戶端服務的Android異步任務錯誤

Question

我正在創建一個運行Windows服務的簡單系統，其中包含一個用戶表，並且我想通過向服務發送一些內容來驗證某人的登錄憑據。我正在嘗試發送他們的用戶名和密碼，但我一直收到與我的異步任務有關的錯誤。我知道你不應該在那裏混淆UI的東西，我不是。原本我打電話給那裏的另一項活動，但我評論說。現在doInBackground中唯一的事情是如果驗證是好的，則將布爾值設置爲true。在那裏，我讀取了異步執行後的值，然後將一個捆綁到一起移動到下一個地方。我只是不知道這裏有什麼問題。自從我在Android中進行編程已經有一段時間了，所以也許我錯過了一些愚蠢的東西。如果有人能幫助我，我將不勝感激！謝謝。將這些信息發送給服務可能也是一個問題？

更新：在清單中添加互聯網使用情況後，如果我在doInBackground中的程序中有log.d，它會打印出來。如果我沒有它，結果值保持錯誤。它看起來像有一些問題，我的服務和Android應用之間的連接...

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.content.Intent; 
import android.view.Menu; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Toast; 

public class LoginActivity extends Activity { 
    private static final int DATA_FROM_MAIN_ACTIVITY = 1; 
    private static final String SERVICEURL = "http://localhost:56638/ClientService.svc"; 
    private EditText userTextBox, passTextBox; 
    private Button loginButton; 
    private String uName, pass; 
    private Boolean result = false; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_login); 

     userTextBox = (EditText) findViewById(R.id.userTextBox); 
     passTextBox = (EditText) findViewById(R.id.passTextBox); 
     loginButton = (Button) findViewById(R.id.loginButton); 

     loginButton.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 

       uName = userTextBox.getText().toString(); 
       pass = passTextBox.getText().toString(); 

       SendLoginMessage task = new SendLoginMessage(); 
       task.execute(uName, pass); 

       if (result.equals(true)) { 
        Intent goToMainScreen = new Intent(getApplicationContext(), 
          MainActivity.class); 
        goToMainScreen.putExtra("username", uName); 
        goToMainScreen.putExtra("password", pass); 

        startActivityForResult(goToMainScreen, 
          DATA_FROM_MAIN_ACTIVITY); 
       } else { 
        Toast.makeText(
          getApplicationContext(), 
          "There was an issue with your username or password.", 
          Toast.LENGTH_LONG).show(); 
       } 

      } 
     }); 

    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.main, menu); 
     return true; 
    } 

    private class SendLoginMessage extends AsyncTask<String, String, Void> { 
     @Override 
     protected void onPreExecute() { 
      // Log.d("message almost at server, " + textFromArea, selected, 
      // null); 
     } 

     @Override 
     protected Void doInBackground(String... names) { 
      ArrayList<NameValuePair> postParams = new ArrayList<NameValuePair>(); 
      postParams.add(new BasicNameValuePair("username", names[0])); 
      postParams.add(new BasicNameValuePair("password", names[1])); 

      String response = null; 

      try { 
       response = HttpClient.executeHttpPost(SERVICEURL, postParams); 

       String newResponse = response.toString(); 
       newResponse = newResponse.replaceAll("\\s+", ""); 

       // if user was authenticated... 
       if (newResponse.equals(true)) { 
        result = true; 
        // creating an intent to take user to next page. 
        // load their DB objects on the 
        // on create in other activity 
        // pass the username/password to next activity 
        // then make a request to the server for their database 
        // objects. 
        // Intent goToMainScreen = new 
        // Intent(getApplicationContext(), MainActivity.class); 
        // goToMainScreen.putExtra("username", names[0]); 
        // goToMainScreen.putExtra("password", names[1]); 

        // startActivityForResult(goToMainScreen, 
        // DATA_FROM_MAIN_ACTIVITY); 
       } 

      } catch (Exception e) { 
       Log.d("ERROR", "exception in background"); 
      } 

      return null; 

     } 

     @Override 
     protected void onPostExecute(Void result) { 

      // Toast.makeText(getApplicationContext(), 
      // .show(); 

     } 

    } 

} 

Answer 1

做這樣的：

private class SendLoginMessage extends AsyncTask<String, String, Boolean> { 
    @Override 
    protected Boolean doInBackground(String... names) { 
     ArrayList<NameValuePair> postParams = new ArrayList<NameValuePair>(); 
     postParams.add(new BasicNameValuePair("username", names[0])); 
     postParams.add(new BasicNameValuePair("password", names[1])); 

     String response = null; 

     try { 
      response = HttpClient.executeHttpPost(SERVICEURL, postParams); 

      String newResponse = response.toString(); 
      newResponse = newResponse.replaceAll("\\s+", ""); 

      // if user was authenticated... 
      if (newResponse.equals("true")) { 
       return true; 
      } 

     } catch (Exception e) { 
      Log.d("ERROR", "exception in background"); 
     } 

     return false; 

    } 

    @Override 
    protected void onPostExecute(Boolean result) { 
      if (result) { 
       Intent goToMainScreen = new Intent(getApplicationContext(), 
         MainActivity.class); 
       goToMainScreen.putExtra("username", uName); 
       goToMainScreen.putExtra("password", pass); 

       startActivityForResult(goToMainScreen, 
         DATA_FROM_MAIN_ACTIVITY); 
      } else { 
       Toast.makeText(
         getApplicationContext(), 
         "There was an issue with your username or password.", 
         Toast.LENGTH_LONG).show(); 
      } 
    } 

} 

，並在您onClick()就叫​​

uName = userTextBox.getText().toString(); 
pass = passTextBox.getText().toString(); 

SendLoginMessage task = new SendLoginMessage(); 
task.execute(uName, pass); 

執行結束後onPostExecute()將被調用，並且您的Activity將根據結果變量啓動。

由於​​被異步調用，因此在調用​​之後不要檢查結果變量。在您檢查全局結果變量時，您的doInBackground()可能尚未完成。使用我的方法你不需要一個全局變量。使用任何組件前請仔細閱讀文檔。