的Android AIDL的IBinder NullPointerException异常

Question

用途：使用AIDL通信的两个应用程序（一个被称为服务，一个被称为客户端）

条件：IDE：Android Studio中，在服务，我定义了一个IPerson.aidl（在这个文件我定义了一个名为queryPerson的接口），AS将在GENERATED dir中生成IPerson.java。我还在main中添加IntentFilter（action，category）AndroidMainfest.xml并创建一个AIDLService来扩展IPerson.Stub并实现接口queryPerson。从那以后，我让所谓的客户端与服务进行通信的另一个应用程序，但有NOPOINTER异常

这里是代码服务： IPerson.aidl：

// IPerson.aidl 
package com.example.jason.aidldemo; 

// Declare any non-default types here with import statements 

interface IPerson { 
    /** 
    * Demonstrates some basic types that you can use as parameters 
    * and return values in AIDL. 
    */ 

    String queryPerson(int num); 
} 

AIDLService.java：

package com.example.jason.aidldemo; 

import android.app.Service; 
import android.content.Intent; 
import android.os.IBinder; 
import android.os.RemoteException; 

public class AIDLService extends Service { 

    private IBinder iBinder=new PersonQueryBinder(); 

    private String [] names={"Apple","Banana","peach"}; 

    private String query(int num) 
    { 
     if(num>0 && num<4) 
     { 
      return names[num-1]; 
     } 
     return null; 
    } 
    public AIDLService() { 
    } 

    private final class PersonQueryBinder extends IPerson.Stub 
    { 
     @Override 
     public String queryPerson(int num) throws RemoteException { 
      return query(num); 
     } 
    } 
    @Override 
    public IBinder onBind(Intent intent) { 
     // TODO: Return the communication channel to the service. 
     return null; 
    } 
} 

AndroidMainfest .xml：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.example.jason.aidldemo" > 

    <application 
     android:allowBackup="true" 
     android:icon="@mipmap/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name=".MainActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 

     <service 
      android:name=".AIDLService" 
      android:enabled="true" 
      android:exported="true" > 
      <intent-filter> 
       <action android:name="android.intent.action.AIDLService"/> 
       <category android:name="android.intent.category.DEFAULT"/> 
      </intent-filter> 
     </service> 
    </application> 

</manifest> 

在客户端：

活动的main.xml中：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context=".MainActivity"> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="@string/hello_world" 
     android:id="@+id/textView" /> 
    <EditText 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:id="@+id/edit_num" 
     android:layout_below="@+id/textView" 
     android:layout_alignParentStart="true" /> 

    <Button 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Query" 
     android:id="@+id/btn_query" 
     android:layout_below="@+id/edit_num" 
     android:layout_alignParentStart="true" 
     android:layout_marginTop="26dp" /> 
    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/tx_name" 
     android:layout_marginTop="20dp" 
     android:layout_below="@+id/btn_query" /> 
</RelativeLayout> 

MainActivity.java：

package com.example.jason.aidlclient; 

import android.app.Activity; 
import android.content.ComponentName; 
import android.content.Intent; 
import android.content.ServiceConnection; 
import android.os.IBinder; 
import android.os.RemoteException; 
import android.support.v7.app.ActionBarActivity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 

import com.example.jason.aidldemo.IPerson; 


public class MainActivity extends Activity implements View.OnClickListener { 

    private IPerson iPerson; 
    private Button btn_query; 
    private TextView tx_name; 
    private EditText edit_name; 
    private PersonConnection pconn=new PersonConnection(); 


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

     bindView(); 
     //bind remoted service 
     Intent service=new Intent("android.intent.action.AIDLService"); 
     service.setPackage("com.example.jason.aidldemo"); 
     bindService(service,pconn,BIND_AUTO_CREATE); 

    } 

    private void bindView() 
    { 
     edit_name= (EditText) findViewById(R.id.edit_num); 
     btn_query= (Button) findViewById(R.id.btn_query); 
     tx_name= (TextView) findViewById(R.id.tx_name); 
     btn_query.setOnClickListener(this); 
    } 

    /** 
    * Called when a view has been clicked. 
    * 
    * @param v The view that was clicked. 
    */ 
    @Override 
    public void onClick(View v) { 
     switch (v.getId()) 
     { 
      case R.id.btn_query: 
       String number=edit_name.getText().toString(); 
       int num=Integer.valueOf(number); 
       try{ 
        String temp=iPerson.queryPerson(num); 
        tx_name.setText(temp); 
       } catch (RemoteException e) { 
        e.printStackTrace(); 
       } 
       edit_name.setText(""); 
       break; 
     } 
    } 

    private final class PersonConnection implements ServiceConnection{ 


     @Override 
     public void onServiceConnected(ComponentName name, IBinder service) { 
      iPerson= (IPerson.Stub) IPerson.Stub.asInterface(service); 
     } 

     @Override 
     public void onServiceDisconnected(ComponentName name) { 
      iPerson=null; 
     } 
    } 

} 

而且我想演示这样运行：

enter image description here

但有问题NOPOINTER 希望有人教我！谢谢！！

Answer 1

您的服务正在返回空活页夹。你必须返回AIDL接口存根这样的：

@Override 
public IBinder onBind(Intent intent) { 
    // TODO: Return the communication channel to the service. 
    return new IPerson.Stub(){ 
      @Override 
      public String queryPerson(int num) throws RemoteException { 
       return query(num); 
      } 
     } 
}