android 中aidl可以传递哪些数据 android aidl例子

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mob64ca140d2323 2023-10-25 06:54:36

文章标签 移动开发 java python android 客户端 文章分类 Android 移动开发

为使应用程序之间能够彼此通信，Android提供了IPC （Inter Process Communication，进程间通信）的一种独特实现： AIDL （Android Interface Definition Language， Android接口定义语言）。

建立两个Android项目，一个是client，一个是server（提供service）。

这篇文章将通过一个项目来介绍AIDL用法，包含了service和client。可能简单了些，不过轻省许多。

本文提供了一个关于AIDL使用的简单易懂的例子，分为客户端和服务端两部分，分别为客户端和服务端新建一个eclipse工程，实现了从客户端向服务端发送请求，服务端打印log的功能。

客户端和服务端的源码结构如下：

注意，由于客户端和服务端的aidl文件所在包名必须一样，而两个包名一样的程序在安装时会产生冲突，所以这里用了一个技巧，在客户端工程的AndroidManifest.xml里把包名指定为com.styleflying，所以大家就会看到gen目录下的R.java所在的包是com.styleflying而不是com.styleflying.AIDL

现在客户端和服务端工程分别新建一个aidl接口，所在包和文件名必须一样。两个aidl接口是一样的，内容如下：

package com.styleflying.AIDL;
interface mInterface{
	void invokTest();
}
package com.styleflying.AIDL;
interface mInterface{
	void invokTest();
}

自动编译生成.java文件如下：

package com.styleflying.AIDL;
public interface mInterface extends IInterface {
    /** Local-side IPC implementation stub class. */
    public static abstract class Stub extends Binder implements mInterface {
        private static final String DESCRIPTOR = "com.styleflying.AIDL.mInterface";
        /** Construct the stub at attach it to the interface. */
        public Stub() {
            this.attachInterface(this, DESCRIPTOR);
	}
	
	/**
	 * Cast an IBinder object into an com.styleflying.AIDL.mInterface interface,
	 * generating a proxy if needed.
	 */
	public static mInterface asInterface(IBinder obj) {
	    if ((obj==null)) {
		return null;
	    }
	    IInterface iin = (IInterface)obj.queryLocalInterface(DESCRIPTOR);
	    if (((iin!=null)&&(iin instanceof mInterface))) {
		return ((com.styleflying.AIDL.mInterface)iin);
	    }
	    return new com.styleflying.AIDL.mInterface.Stub.Proxy(obj);
	}
	
	public android.os.IBinder asBinder() {
	    return this;
	}
	
	@Override 
	public boolean onTransact(int code, Parcel data, Parcel reply, int flags) 
	        throws RemoteException {
	    switch (code) {
		case INTERFACE_TRANSACTION:
		    reply.writeString(DESCRIPTOR);
		    return true;
		case TRANSACTION_invokTest:
		    data.enforceInterface(DESCRIPTOR);
		    this.invokTest();
		    reply.writeNoException();
		    return true;
	    }
	    return super.onTransact(code, data, reply, flags);
	}
	
	private static class Proxy implements mInterface {
	    private IBinder mRemote;
	    Proxy(IBinder remote) {
		mRemote = remote;
	    }
	    public IBinder asBinder() {
		return mRemote;
	    }
	    public String getInterfaceDescriptor() {
		return DESCRIPTOR;
	    }
	    public void invokTest() throws RemoteException {
		Parcel _data = Parcel.obtain();
		Parcel _reply = Parcel.obtain();
		try {
		    _data.writeInterfaceToken(DESCRIPTOR);
		    mRemote.transact(Stub.TRANSACTION_invokTest, _data, _reply, 0);
		    _reply.readException();
		}finally {
		    _reply.recycle();
		    _data.recycle();
		}
	    }
        }
    
        static final int TRANSACTION_invokTest = (IBinder.FIRST_CALL_TRANSACTION + 0);
    }
    public void invokTest() throws RemoteException;
}
package com.styleflying.AIDL;
public interface mInterface extends IInterface {
    /** Local-side IPC implementation stub class. */
    public static abstract class Stub extends Binder implements mInterface {
        private static final String DESCRIPTOR = "com.styleflying.AIDL.mInterface";
        /** Construct the stub at attach it to the interface. */
        public Stub() {
            this.attachInterface(this, DESCRIPTOR);
	}
	
	/**
	 * Cast an IBinder object into an com.styleflying.AIDL.mInterface interface,
	 * generating a proxy if needed.
	 */
	public static mInterface asInterface(IBinder obj) {
	    if ((obj==null)) {
		return null;
	    }
	    IInterface iin = (IInterface)obj.queryLocalInterface(DESCRIPTOR);
	    if (((iin!=null)&&(iin instanceof mInterface))) {
		return ((com.styleflying.AIDL.mInterface)iin);
	    }
	    return new com.styleflying.AIDL.mInterface.Stub.Proxy(obj);
	}
	
	public android.os.IBinder asBinder() {
	    return this;
	}
	
	@Override 
	public boolean onTransact(int code, Parcel data, Parcel reply, int flags) 
	        throws RemoteException {
	    switch (code) {
		case INTERFACE_TRANSACTION:
		    reply.writeString(DESCRIPTOR);
		    return true;
		case TRANSACTION_invokTest:
		    data.enforceInterface(DESCRIPTOR);
		    this.invokTest();
		    reply.writeNoException();
		    return true;
	    }
	    return super.onTransact(code, data, reply, flags);
	}
	
	private static class Proxy implements mInterface {
	    private IBinder mRemote;
	    Proxy(IBinder remote) {
		mRemote = remote;
	    }
	    public IBinder asBinder() {
		return mRemote;
	    }
	    public String getInterfaceDescriptor() {
		return DESCRIPTOR;
	    }
	    public void invokTest() throws RemoteException {
		Parcel _data = Parcel.obtain();
		Parcel _reply = Parcel.obtain();
		try {
		    _data.writeInterfaceToken(DESCRIPTOR);
		    mRemote.transact(Stub.TRANSACTION_invokTest, _data, _reply, 0);
		    _reply.readException();
		}finally {
		    _reply.recycle();
		    _data.recycle();
		}
	    }
        }
    
        static final int TRANSACTION_invokTest = (IBinder.FIRST_CALL_TRANSACTION + 0);
    }
    public void invokTest() throws RemoteException;
}

客户端的mAIDLActivity.java如下：

package com.styleflying.AIDL;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import com.styleflying.R;
public class mAIDLActivity extends Activity {
	
	private static final String TAG = "AIDLActivity";
	private Button btnOk;
	private Button btnCancel;
	private Button btnCallBack;
	
	private void Log(String str){
		Log.d(TAG,"----------" + str + "----------");
	}
	
		
	mInterface mService;
	private ServiceConnection mConnection = new ServiceConnection(){
		public void onServiceConnected(ComponentName className,
				IBinder service){
			Log("connect service");
			mService = mInterface.Stub.asInterface(service);
		}
		
		public void onServiceDisconnected(ComponentName className){
			Log("disconnect service");
			mService = null;
		}
	};
	
	
	
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.main);
        
        btnOk = (Button)findViewById(R.id.btn_ok);
        btnCancel = (Button)findViewById(R.id.btn_cancel);
        btnCallBack = (Button)findViewById(R.id.btn_callback);
        
        btnOk.setOnClickListener(new OnClickListener(){
        	public void onClick(View v){
        		Bundle args = new Bundle();
        		Intent intent = new Intent("com.styleflying.AIDL.service");
        		intent.putExtras(args);
        		bindService(intent,mConnection,Context.BIND_AUTO_CREATE);
        	}
        });
        
        btnCancel.setOnClickListener(new OnClickListener(){
        	public void onClick(View v){
        		unbindService(mConnection);
        	}
        });  	
        btnCallBack.setOnClickListener(new OnClickListener(){
        	public void onClick(View v){
        		try{
        			Log.i(TAG,"current Thread id = " + Thread.currentThread().getId());
        			mService.invokTest();
        		}
        		catch(RemoteException e){
        			
        		}
        	}
        });
        
        
    }
}
package com.styleflying.AIDL;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import com.styleflying.R;
public class mAIDLActivity extends Activity {
	
	private static final String TAG = "AIDLActivity";
	private Button btnOk;
	private Button btnCancel;
	private Button btnCallBack;
	
	private void Log(String str){
		Log.d(TAG,"----------" + str + "----------");
	}
	
		
	mInterface mService;
	private ServiceConnection mConnection = new ServiceConnection(){
		public void onServiceConnected(ComponentName className,
				IBinder service){
			Log("connect service");
			mService = mInterface.Stub.asInterface(service);
		}
		
		public void onServiceDisconnected(ComponentName className){
			Log("disconnect service");
			mService = null;
		}
	};
	
	
	
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.main);
        
        btnOk = (Button)findViewById(R.id.btn_ok);
        btnCancel = (Button)findViewById(R.id.btn_cancel);
        btnCallBack = (Button)findViewById(R.id.btn_callback);
        
        btnOk.setOnClickListener(new OnClickListener(){
        	public void onClick(View v){
        		Bundle args = new Bundle();
        		Intent intent = new Intent("com.styleflying.AIDL.service");
        		intent.putExtras(args);
        		bindService(intent,mConnection,Context.BIND_AUTO_CREATE);
        	}
        });
        
        btnCancel.setOnClickListener(new OnClickListener(){
        	public void onClick(View v){
        		unbindService(mConnection);
        	}
        });  	
        btnCallBack.setOnClickListener(new OnClickListener(){
        	public void onClick(View v){
        		try{
        			Log.i(TAG,"current Thread id = " + Thread.currentThread().getId());
        			mService.invokTest();
        		}
        		catch(RemoteException e){
        			
        		}
        	}
        });
        
        
    }
}

客户端在执行bindService的时候，成功绑定服务之后，会回调mConnection的onServiceConnected(),并且传回了服务端的通信接口IBinder，此IBinder即服务onBind()时返回的IBinder，详见mAIDLService.java。

在onServiceConnected(),客户端成功获取了服务端通信接口，实际上是本地代理对象，该对象存在于客户端进程空间，客户端只和代理对象交互，真正的IPC通信是本地代理对象和服务端的通信。

mAIDLService.java如下：

package com.styleflying.AIDL;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.Looper;
import android.os.RemoteException;
import android.util.Log;
import android.widget.Toast;
public class mAIDLService extends Service{

    private static final String TAG = "AIDLService";
	
    private void Log(String str){
	Log.i(TAG,"----------" + str + "----------");
    }
	
    public void onCreate(){
	Log("service created");
    }
	
    public void onStart(Intent intent, int startId){
	Log("service started id = " + startId);
    }
	
    public IBinder onBind(Intent t){
	Log("service on bind");
	return mBinder;
    }
	
    public void onDestroy(){
	Log("service on destroy");
	super.onDestroy();
    }
	
    public boolean onUnbind(Intent intent){
	Log("service on unbind");
	return super.onUnbind(intent);
    }
	
    public void onRebind(Intent intent){
	Log("service on rebind");
	super.onRebind(intent);
    }
	
	
    private final mInterface.Stub mBinder = new mInterface.Stub() {		
	public void invokTest() throws RemoteException {
	    // TODO Auto-generated method stub
	    Log.e(TAG, "remote call from client! current thread id = " + Thread.currentThread().getId());
	}
    };
}
package com.styleflying.AIDL;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.Looper;
import android.os.RemoteException;
import android.util.Log;
import android.widget.Toast;
public class mAIDLService extends Service{

    private static final String TAG = "AIDLService";
	
    private void Log(String str){
	Log.i(TAG,"----------" + str + "----------");
    }
	
    public void onCreate(){
	Log("service created");
    }
	
    public void onStart(Intent intent, int startId){
	Log("service started id = " + startId);
    }
	
    public IBinder onBind(Intent t){
	Log("service on bind");
	return mBinder;
    }
	
    public void onDestroy(){
	Log("service on destroy");
	super.onDestroy();
    }
	
    public boolean onUnbind(Intent intent){
	Log("service on unbind");
	return super.onUnbind(intent);
    }
	
    public void onRebind(Intent intent){
	Log("service on rebind");
	super.onRebind(intent);
    }
	
	
    private final mInterface.Stub mBinder = new mInterface.Stub() {		
	public void invokTest() throws RemoteException {
	    // TODO Auto-generated method stub
	    Log.e(TAG, "remote call from client! current thread id = " + Thread.currentThread().getId());
	}
    };
}

注意onBind()函数，返回了mBinder，而mBinder实现了mInterface.Stub，实现了mInterface接口，执行了打印log的操作。

整个交互流程如下：

1）客户端通过绑定服务，获取了服务的句柄(本地代理对象)；

2）客户端执行onClick()，调用本地代理对象的invokTest()函数，本地代理对象调用mRemote.transact()发出远程调用请求（见 mInterface.java）；

3）服务端响应onTransact()执行this.invokTest()，并将执行结果返回；

由于客户端只和本地代理对象即服务句柄通信，由代理对象进行真正的IPC操作，所以对客户端来说，IPC过程是透明的，调用远程操作如同调用本地操作一样。在客户端调用transact()时，会将服务描述DSCRIPTION写入到data里，在客户端onTransact时会验证，如果两个不一样，则不能通信。而DSCRIPTION是根据mInterface包名和接口名自动生成的，这就是为什么两个工程里的mInterface.aidl要在同一个包的原因。

在这个过程中，mInterface.aidl起到了桥梁的作用，规定统一了客户端和服务端的通信接口，使得客户端和服务端得以成功的通信。

具体的通信transact和onTransact的过程也就是利用Binder驱动通信的过程，在这里就不多叙述。

最后补上两个工程的AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.styleflying"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".AIDL.mAIDLActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-sdk android:minSdkVersion="8" />
</manifest>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.styleflying"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".AIDL.mAIDLActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-sdk android:minSdkVersion="8" />
</manifest>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.styleflying.AIDL"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <service android:name=".mAIDLService">
        		<intent-filter>
                <action android:name="com.styleflying.AIDL.service" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </service>
    </application>
    <uses-sdk android:minSdkVersion="8" />
</manifest>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.styleflying.AIDL"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <service android:name=".mAIDLService">
        		<intent-filter>
                <action android:name="com.styleflying.AIDL.service" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </service>
    </application>
    <uses-sdk android:minSdkVersion="8" />
</manifest>

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