用户名和登录与AsyncTask

Question

我最近遵循如何处理用户名和使用PHP和MySQL登录指南。不幸的是，该指南并未涵盖现在需要的AsyncTasks，因为android不允许我在主线程上执行任何网络内容。 （This is the guide）

我用下面的代码。 （在底部创建一个AsyncTask，并移动登录按钮的OnClick Listener的内容，并将其移动到AsyncTask并使该按钮执行asynctask。我是AsyncTask的新手，因此可能存在多个问题。恳求让我知道

Error: 01-22 10:25:13.140 3774-3788/com.Ayman.jokeit E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #2 
    Process: com.Ayman.jokeit, PID: 3774 
    java.lang.RuntimeException: An error occured while executing doInBackground() 
      at android.os.AsyncTask$3.done(AsyncTask.java:300) 
      at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) 
      at java.util.concurrent.FutureTask.setException(FutureTask.java:222) 
      at java.util.concurrent.FutureTask.run(FutureTask.java:242) 
      at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
      at java.lang.Thread.run(Thread.java:841) 
    Caused by: java.lang.NullPointerException 
      at com.Ayman.jokeit.LoginActivity$LoginTask.doInBackground(LoginActivity.java:81) 
      at com.Ayman.jokeit.LoginActivity$LoginTask.doInBackground(LoginActivity.java:70) 
      at android.os.AsyncTask$2.call(AsyncTask.java:288) 
      at java.util.concurrent.FutureTask.run(FutureTask.java:237) 
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
            at java.lang.Thread.run(Thread.java:841) 

我包括以下相关代码：。

package com.Ayman.jokeit; 

import org.json.JSONException; 
import org.json.JSONObject; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 

import com.Ayman.jokeit.library.DatabaseHandler; 
import com.Ayman.jokeit.library.UserFunctions; 

public class LoginActivity extends Activity { 
    Button btnLogin; 
    Button btnLinkToRegister; 
    EditText inputEmail; 
    EditText inputPassword; 
    TextView loginErrorMsg; 

    // JSON Response node names 
    private static String KEY_SUCCESS = "success"; 
    private static String KEY_ERROR = "error"; 
    private static String KEY_ERROR_MSG = "error_msg"; 
    private static String KEY_UID = "uid"; 
    private static String KEY_NAME = "name"; 
    private static String KEY_EMAIL = "email"; 
    private static String KEY_CREATED_AT = "created_at"; 

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

     // Importing all assets like buttons, text fields 
     inputEmail = (EditText) findViewById(R.id.loginEmail); 
     inputPassword = (EditText) findViewById(R.id.loginPassword); 
     btnLogin = (Button) findViewById(R.id.btnLogin); 
     btnLinkToRegister = (Button) findViewById(R.id.btnLinkToRegisterScreen); 
     loginErrorMsg = (TextView) findViewById(R.id.login_error); 

     // Login button Click Event 
     btnLogin.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View view) { 
       //if you want to keep the loader from Ravi 

       //and then, you add the AsyncTask 
       LoginTask AsyncLogin = new LoginTask(); 
       AsyncLogin.execute(); 
      } 

     }); 

     // Link to Register Screen 
     btnLinkToRegister.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View view) { 
       Intent i = new Intent(getApplicationContext(), 
         RegisterActivity.class); 
       startActivity(i); 
       finish(); 
      } 
     }); 
    } 
    public class LoginTask extends AsyncTask<String, Void, Void> { 

     @Override 
     protected Void doInBackground(String... strings) { 
      String email = inputEmail.getText().toString(); 
      String password = inputPassword.getText().toString(); 
      UserFunctions userFunction = new UserFunctions(); 
      JSONObject json = userFunction.loginUser(email, password); 

      // check for login response 
      try { 
       if (json.getString(KEY_SUCCESS) != null) { 
        loginErrorMsg.setText(""); 
        String res = json.getString(KEY_SUCCESS); 
        if(Integer.parseInt(res) == 1){ 
         // user successfully logged in 
         // Store user details in SQLite Database 
         DatabaseHandler db = new DatabaseHandler(getApplicationContext()); 
         JSONObject json_user = json.getJSONObject("user"); 

         // Clear all previous data in database 
         userFunction.logoutUser(getApplicationContext()); 
         db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT)); 

         // Launch Dashboard Screen 
         Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class); 

         // Close all views before launching Dashboard 
         dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
         startActivity(dashboard); 

         // Close Login Screen 
         finish(); 
        }else{ 
         // Error in login 
         loginErrorMsg.setText("Incorrect username/password"); 
        } 
       } 
      } catch (JSONException e) { 
       e.printStackTrace(); 
      } 

      return null; 
     } 
    } 
} 

Answer 1

似乎有什么不对的UserFunctions类loginUser方法，我相信你的Android的代码无法达到你的php server。你需要检查你的php服务器是否运行& running（假设你建立了一个）。你能每个yourIp/ah_login_api/login /？是否有可能错过了在UserFunctions.java中更改ip？