Android中的跨进程回调

在Android应用程序开发中，可能会遇到跨进程回调问题，比如，调用一个服务，但服务是异步的，服务完成后，需要给客户一个通知，这时就需要用到跨进程回调了。跨进程回调本质上用到了Binder机制，其过程如下：

1.定义aidl

ITest.aidl

package com.example.chirpdemo;
import com.example.chirpdemo.ITestListener;

interface ITest {
int getValue();
void setValue(int value);
void listen(ITestListener listener);
}

ITestListener.aidl

package com.example.chirpdemo;

interface ITestListener {
void onFinished(int result);
}

2.Service定义如下：

package com.example.chirpdemo;

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

public class MyService extends Service {
    final private static String TAG = "MyService";

    public class ServiceImpl extends ITest.Stub {
        private int mValue;
        private ITestListener mListener;

        public ServiceImpl() {
            mValue = 0;
        }

        @Override
        public int getValue() throws RemoteException {
            return mValue;
        }

        @Override
        public void setValue(int value) throws RemoteException {
            mValue = value;

            if (null != mListener) {
                mListener.onFinished(-1);
            }
        }

        @Override
        public void listen(ITestListener listener) throws RemoteException {
            mListener = listener;
        }
    }

    @Override
    public void onCreate() {
        Log.d(TAG, "onCreate");
        super.onCreate();
    }

    @Override
    public void onDestroy() {
        Log.d(TAG, "onDestroy");
        super.onDestroy();
    }

    @Override
    public void onStart(Intent intent, int startId) {
        Log.d(TAG, "onStart");
        super.onStart(intent, startId);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.d(TAG, "onStartCommand");
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public boolean onUnbind(Intent intent) {
        Log.d(TAG, "onUnbind");
        return super.onUnbind(intent);
    }

    @Override
    public void onRebind(Intent intent) {
        Log.d(TAG, "onRebind");
        super.onRebind(intent);
    }

    @Override
    public IBinder onBind(Intent arg0) {
        return new ServiceImpl();
    }

}

3.Client定义如下：

package com.example.easytabdemo;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.graphics.PixelFormat;
import android.graphics.drawable.Drawable;
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.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.example.chirpdemo.ITest;
import com.example.chirpdemo.ITestListener;
import com.example.easytabdemo.SlideTabHost.TabSpec;

public class MainActivity extends Activity {
    final private static String TAG = "MainActivity";
        
    final Intent myIntent = new Intent("com.pyk.les.IlongExistService");
    private boolean startedService = false;
    private ITest leservice = null;
    ServiceConnection myServiceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            leservice = ITest.Stub.asInterface(service);
            
            try {
                leservice.listen(new ITestListener.Stub() {

                    @Override
                    public void onFinished(int result) throws RemoteException {
                    }
                    
                });
            } catch (RemoteException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            leservice = null;
            Log.i("aaaaaaaaaaaa", "onDisconnected:" + Thread.currentThread());
        }
    };

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

        startedService = bindService(new Intent("com.my.IService"),
                myServiceConnection, BIND_AUTO_CREATE);
        Log.i("aaaaaaaaaaaa", "bindService:" + Thread.currentThread());
        
        Button bt = (Button)this.findViewById(R.id.bt1);
        bt.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                if ( startedService ) {
                    if ( null != leservice ) {
                        try {
                            leservice.setValue(leservice.getValue() + 1);
                        } catch (RemoteException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        });
        
        view.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                if ( startedService ) {
                    if ( null != leservice ) {
                        try {
                            mEditText.setText(leservice.getValue() + "");
                        } catch (RemoteException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        });
    }

    @Override
    public void onStart() {
        super.onStart();
        Log.i("aaaaaaaa", "onStart");
    }

    @Override
    public void onPause() {
        super.onPause();
        Log.i("aaaaaaaa", "onPause");
    }

    @Override
    public void onResume() {
        super.onResume();
        Log.i("aaaaaaaa", "onResume");
    }

    @Override
    public void onStop() {
        super.onStop();
        Log.i("aaaaaaaa", "onStop");
    }

    @Override
    protected void onDestroy() {
        if (startedService) {
            unbindService(myServiceConnection);
        }
        Log.i(TAG, "onDestroy");
        super.onDestroy();
    }
}

在以上代码中ITestListener为跨进程回调接口