通过 Handler 、Messenger、Message 实现跨进程通信（IPC）
- 实际传递的是Message，可以复用信息池
- 支持信息回调
- 不需要编写aidl
-
Server 端 MyService 实现 代码：
public class MyService extends Service { private static final int RECEIVE_MESSAGE_CODE = 0x0001; private static final int SEND_MESSAGE_CODE = 0x0002; //保存当前连接的所有 客户端. ArrayList<Messenger> mClients = new ArrayList<>(); static final int MSG_REGISTER_CLIENT = 1; static final int MSG_UNREGISTER_CLIENT = 2; static final int MSG_SET_VALUE = 3; private Messenger clientMessenger = null; private Messenger serviceMessenger = new Messenger(new ServiceHandler()); private class ServiceHandler extends Handler { @Override public void handleMessage(@NonNull Message msg) { super.handleMessage(msg); Log.d("MyService", "handleMessage:" + msg.what); switch (msg.what) { case MSG_REGISTER_CLIENT: Log.d("MyService", "client added :" + msg.replyTo.toString()); mClients.add(msg.replyTo); break; case MSG_UNREGISTER_CLIENT: mClients.remove(msg.replyTo); break; case MSG_SET_VALUE: int a = msg.arg1; int b = msg.arg2; int c = a+b; for (int i = mClients.size() - 1; i >= 0; i--) { try { Thread.sleep(5000);//模拟耗时 // 给 客户端发消息 mClients.get(i).send(Message.obtain(null, MSG_SET_VALUE, c, 0)); } catch (RemoteException | InterruptedException e) { mClients.remove(i);// 客户端连接异常， 删除客户端 } } break; default: super.handleMessage(msg); } } }// end ServiceHandler @Override public IBinder onBind(Intent intent) { Log.d("MyService", "onBind:"); return serviceMessenger.getBinder(); } @Override public void onDestroy() { Log.d("MyService", "onDestroy:"); super.onDestroy(); clientMessenger = null; } }
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Client 端 MainActivity 实现 代码：
public class MainActivity extends AppCompatActivity {
private Button mBtBind;
private Button mBtUnBind;
private TextView mTvMsg;
static final int MSG_REGISTER_CLIENT = 1;
static final int MSG_UNREGISTER_CLIENT = 2;
static final int MSG_SET_VALUE = 3;
private boolean isBound = false;
private String SERVICE_ACTION = "tk.iovr.messagehandlerservice.MyService";
private Messenger serviceMessenger = null;
private Messenger clientMessenger = new Messenger(new ClientHandler());
private class ClientHandler extends Handler {
@Override
public void handleMessage(@NonNull Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case MSG_SET_VALUE:
Log.d("MainActivity","Received value from service: " + msg.arg1);
mTvMsg.setText("Received from service: " + msg.arg1);
break;
default:
super.handleMessage(msg);
}
}
}
private ServiceConnection connection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Log.d("MainActivity","onServiceConnected:");
serviceMessenger = new Messenger(service);
isBound = true;
mTvMsg.setText("Attached.");
try {
Message message = Message.obtain(null,MSG_REGISTER_CLIENT);
message.replyTo = clientMessenger;
serviceMessenger.send(message);
int a = new Random().nextInt(10);
int b = new Random().nextInt(10);
Log.d("MainActivity","send to remote a:"+a+", b:"+b);
// 调用 Server 端代码
message = Message.obtain(null,MSG_SET_VALUE, a,b);
serviceMessenger.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
// 发送 参数变量
// Message msg = Message.obtain();
// msg.what =SEND_MESSAGE_CODE;
//
// Bundle data = new Bundle();
// data.putString("msg","你好，MyService，我是客户端");
// msg.setData(data);
//
// msg.replyTo = clientMessenger;
// try {
// serviceMessenger.send(msg);
// } catch (RemoteException e) {
// e.printStackTrace();
// }
}
@Override
public void onServiceDisconnected(ComponentName name) {
serviceMessenger = null;
isBound = false;
mTvMsg.setText("Disconnected.");
Log.d("MainActivity","remote service disconnected:");
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mBtBind = findViewById(R.id.bound);
mBtUnBind = findViewById(R.id.unbound);
mTvMsg = findViewById(R.id.msgshow);
mTvMsg.setText("Not attached.");
mBtBind.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!isBound){
doBindService();
}
}
});
mBtUnBind.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (isBound){
doUnBindService();
}
}
});
}
private void doBindService() {
Log.d("mainActivity","doBindService");
//Android 11 查询其他应用 信息需要获取权限 详见 AndroidManifest.xml
Intent intent = new Intent(SERVICE_ACTION);
intent.setComponent(new ComponentName("tk.iovr.messagehandlerservice",
"tk.iovr.messagehandlerservice.MyService"));
mTvMsg.setText("Binding.");
bindService(intent,connection,BIND_AUTO_CREATE);//绑定服务
isBound = true;
}
private void doUnBindService() {
Log.d("mainActivity","doUnBindService");
if (isBound){
if (serviceMessenger !=null){
try {
//发送解绑消息
Message message = Message.obtain(null,MSG_UNREGISTER_CLIENT);
message.replyTo = clientMessenger;
serviceMessenger.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
unbindService(connection); //解绑服务
isBound = false;
mTvMsg.setText("Unbinding");
}
}
}客户端 在 setComponent 来 BindService 时，Android 11 上面 查询其他 应用信息 需要进行权限申请：
-
第一种方式：只指定需要查询 的应用包名
<queries> <package android:name="tk.iovr.messagehandlerservice"/> </queries>
第二种方式：声明 查询所有应用信息的权限
-
<uses-permission android:name="android.permission.QUERY_ALL_PACKAGES" tools:ignore="QueryAllPackagesPermission" />
- messenger 适合一个个消息传递，不适合高并发