安卓跨进程通信：Messenger、AIDL远程Service 使用

Messenger

服务端

创建Service：

public class MessengerService extends Service {private static final int MSG_SUM = 0x110;private Messenger messenger = new Messenger(new Handler() {@Overridepublic void handleMessage(@NonNull Message msg) {Message message = Message.obtain(msg);switch (msg.what) {case MSG_SUM:message.what = MSG_SUM;try {Thread.sleep(2000);message.arg2 = msg.arg1 + msg.arg2;msg.replyTo.send(message);} catch (InterruptedException | RemoteException e) {e.printStackTrace();}break;default:break;}super.handleMessage(msg);}});@Nullable@Overridepublic IBinder onBind(Intent intent) {return messenger.getBinder();}
}

在Service中创建Messenger实例，通过Message消息机制进行操作，Service的onBind中返回messenger实例的Binder对象。

注册service：

<serviceandroid:name=".MessengerService"android:enabled="true"android:exported="true"><intent-filter><action android:name="com.example.messengerserver" /></intent-filter>
</service>

此处action值随意设置，后续和intent的action匹配即可。

客户端

public class MainActivity extends AppCompatActivity {private static final int MSG_SUM = 0x110;private Button button;private LinearLayout layout;private TextView mTvState;private Messenger mService;private boolean isConn;private Messenger mMessenger = new Messenger(new Handler() {@Overridepublic void handleMessage(@NonNull Message msg) {switch (msg.what) {case MSG_SUM:TextView tv = (TextView) layout.findViewById(msg.arg1);tv.setText(tv.getText() + "=>" + msg.arg2);break;}super.handleMessage(msg);}});private ServiceConnection mConn = new ServiceConnection() {@Overridepublic void onServiceConnected(ComponentName componentName, IBinder iBinder) {mService = new Messenger(iBinder);isConn = true;mTvState.setText("conn");}@Overridepublic void onServiceDisconnected(ComponentName componentName) {mService = null;isConn = false;mTvState.setText("dis");}};private int mA;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Intent intent = new Intent();
//        intent.setAction("com.example.messengerserver");intent.setPackage("com.example.messengerserver");bindService(intent, mConn, BIND_AUTO_CREATE);mTvState = (TextView) findViewById(R.id.id_tv_callback);button = (Button) findViewById(R.id.id_btn_add);layout = (LinearLayout) findViewById(R.id.id_ll_container);button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {try {int a = mA++;int b = (int) (Math.random() * 100);//创建一个tv,添加到LinearLayout中TextView tv = new TextView(MainActivity.this);tv.setText(a + " + " + b + " = caculating ...");tv.setId(a);layout.addView(tv);Message msg = Message.obtain(null, MSG_SUM, a, b);msg.replyTo = mMessenger;if (isConn) {mService.send(msg);}} catch (RemoteException e) {e.printStackTrace();}}});}
}

注：
①intent设置：隐式必须声明package为service所在包名（而action不必声明，但若声明则必须和服务端设置的action相同，否则service绑定失败）
②ServiceConnection为连接、断开的回调方法
③流程：
a、客户端与服务端通过service绑定成功后，调用ServiceConnection回调方法，客户端依据返回的binder生成给服务端发送信息的messenger

mService = new Messenger(iBinder);

b、客户端创建message给服务端发送

Message msg = Message.obtain(null, MSG_SUM, a, b);
msg.replyTo = mMessenger;      //此处绑定客户端的Messenger，用于接收信息时触发此处的handleMessage
if (isConn) {mService.send(msg);
}

c、服务端接收信息进行数据处理并给在message绑定好的Messenger发送信息

message.arg2 = msg.arg1 + msg.arg2;
msg.replyTo.send(message);

发送回客户端后触发handleMessage

AIDL+远程Service

服务端

interface IPersonAidlInterface {/*** Demonstrates some basic types that you can use as parameters* and return values in AIDL.*/void setName(String name);void setAge(int age);String getInfo();void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat,double aDouble, String aString);
}

创建aidl文件夹及包+aidl文件（包名需与java文件夹内包相同）
aidl文件创建后，makeProject再继续编写。

public class PersonService extends Service {public PersonService() {}@Nullable@Overridepublic IBinder onBind(Intent intent) {return new IPersonImpl();}public class IPersonImpl extends IPersonAidlInterface.Stub {private String name;private int age;@Overridepublic void setName(String name) throws RemoteException {this.name = name;Log.i("server", name);}@Overridepublic void setAge(int age) throws RemoteException {this.age = age;}@Overridepublic String getInfo() throws RemoteException {return "My name is "+name+", age is "+age+"!";}@Overridepublic void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, String aString) throws RemoteException {}}
}

创建aidl.stub子类，重写方法逻辑，在Service的onbind返回stub实例。

声明service：

<service android:name=".PersonService"android:enabled="true"android:exported="true"android:process=":remote"><intent-filter><action android:name="com.example.aidlserver" /></intent-filter>
</service>

此处注意点同messenger

客户端

将服务端创建的aidl文件夹复制到客户端中，再makeProject

public class MainActivity extends AppCompatActivity {private IPersonAidlInterface iPersonAidlInterface;TextView textView;private ServiceConnection serviceConnection = new ServiceConnection() {@Overridepublic void onServiceConnected(ComponentName componentName, IBinder iBinder) {iPersonAidlInterface = IPersonAidlInterface.Stub.asInterface(iBinder);try {iPersonAidlInterface.setName("123");textView.setText(iPersonAidlInterface.getInfo());} catch (RemoteException e) {e.printStackTrace();}}@Overridepublic void onServiceDisconnected(ComponentName componentName) {}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);textView = findViewById(R.id.text);Intent intent = new Intent();
//        intent.setAction("com.example.aidlserver");intent.setPackage("com.example.aidlserver");bindService(intent, serviceConnection, BIND_AUTO_CREATE);}}

注：
①在ServiceConnection中主要执行iPersonAidlInterface = IPersonAidlInterface.Stub.asInterface(iBinder);，后续通过iPersonAidlInterface即可调用服务端方法
②服务绑定注意点与方法和Messenger相同

对比

Messenger主要通过Message消息机制进行通信，省去了AIDL接口的编写与实现
两者都需要通过Service进行服务端、客户端关系绑定，绑定后再实现通信。