Android跨进程通信之Binder连接池及选择合适的IPC方式

借鉴自开发艺术

AIDL是最常用的多进程通信的技术，但是每次使用都要创建一个Service，开销太大，应该把所有的AIDL都放到一个Service里。

每个业务模块都创建自己的AIDL接口并实现，业务模块间不能有耦合，然后向服务器提供自己的唯一标识和对应的Binder对象。对于服务端，1个Service足够了。服务端提供一个queryBinder接口，从中可以获取业务模块对应的Binder。拿到Binder就可以远程调用了。所以，Binder连接池的作用是把所有业务模块的Binder请求统一转发到远程Service中去执行。

原理图

两个AIDL接口及其实现类

// ISecurityCenter.aidl
package com.example.test;

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

interface ISecurityCenter {
String encrypt(String content);
String decrypt(String password);
}

// ICompute.aidl
package com.example.test;

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

interface ICompute {
int add(int a, int b);
}

public class ComputeImpl extends ICompute.Stub {
    @Override
    public int add(int a, int b) throws RemoteException {
        return a + b;
    }
}

public class SecurityCenterImpl extends ISecurityCenter.Stub {

    private static final char SECRET_CODE = '^';


    @Override
    public String encrypt(String content) throws RemoteException {
        char[] chars = content.toCharArray();
        for (int i = 0; i < chars.length; i ++) {
            chars[i] ^= SECRET_CODE;
        }
        return new String(chars);
    }

    @Override
    public String decrypt(String password) throws RemoteException {
        return encrypt(password);
    }
}

一个Binder池接口

// IBinderPool.aidl
package com.example.test;

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

interface IBinderPool {
IBinder queryBinder(int binderCode);
}

Binder池管理类，其实相当于工具类

public class BinderPool {
    private static final String TAG = "BinderPool";
    public static final int BINDER_NONE = -1;
    public static final int BINDER_COMPUTE = 0;
    public static final int BINDER_SECURITY_CENTER = 1;

    private Context mContext;
    private IBinderPool mBinderPool;
    private static volatile BinderPool sInstance;
    private CountDownLatch mConnectionBinderPoolCountDownLatch;

    private BinderPool (Context context) {
        mContext = context.getApplicationContext();
        connectBinderPoolService();
    }

    public static BinderPool getInstance(Context context) {
        if (sInstance == null) {
            synchronized (BinderPool.class) {
                if (sInstance == null) {
                    sInstance = new BinderPool(context);
                }
            }
        }
        return sInstance;
    }

    private synchronized void connectBinderPoolService() {
        mConnectionBinderPoolCountDownLatch = new CountDownLatch(1);
        Intent service = new Intent(mContext, BinderPoolService.class);
        mContext.bindService(service, mBinderPoolConnection, Context.BIND_AUTO_CREATE);
        try {
            mConnectionBinderPoolCountDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public IBinder queryBinder(int binderCode) {
        IBinder binder = null;
        if (mBinderPool != null) {
            try {
                binder = mBinderPool.queryBinder(binderCode);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
        return binder;
    }

    private ServiceConnection mBinderPoolConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            mBinderPool = IBinderPool.Stub.asInterface(service);
            try {
                mBinderPool.asBinder().linkToDeath(mBinderPoolDeathRecipient, 0);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

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

    private IBinder.DeathRecipient mBinderPoolDeathRecipient = new IBinder.DeathRecipient() {
        @Override
        public void binderDied() {
            Log.w(TAG, "binderDied: ");
            mBinderPool.asBinder().unlinkToDeath(mBinderPoolDeathRecipient, 0);
            mBinderPool = null;
            connectBinderPoolService();
        }
    };

    public static class BinderPoolImpl extends IBinderPool.Stub {
        public BinderPoolImpl() {
            super();
        }

        @Override
        public IBinder queryBinder(int binderCode) throws RemoteException {
            IBinder binder = null;
            switch (binderCode) {
                case BINDER_SECURITY_CENTER :
                    binder = new SecurityCenterImpl();
                    break;
                case BINDER_COMPUTE :
                    binder = new ComputeImpl();
                    break;
            }
            return binder;
        }
    }
}

service

public class BinderPoolService extends Service {

    private static final String TAG = "xbh";

    private Binder mBinderPool = new BinderPool.BinderPoolImpl();

    @Override
    public void onCreate() {
        super.onCreate();
    }

    public BinderPoolService() {
    }

    @Override
    public IBinder onBind(Intent intent) {
        Log.i(TAG, "onBind: ");
        return mBinderPool;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
    }
}

调用

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "xbh";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new Thread(new Runnable() {
            @Override
            public void run() {
                doWork();
            }
        }).start();
    }

    private void doWork() {
        BinderPool binderPool = BinderPool.getInstance(this);
        IBinder securityBinder = binderPool.queryBinder(BinderPool.BINDER_SECURITY_CENTER);
        ISecurityCenter mSecurityCenter = SecurityCenterImpl.asInterface(securityBinder);
        Log.i(TAG, "visit ISecurityCenter");
        String msg = "helloworld-安卓";
        Log.i(TAG, msg);
        try {
            String password = mSecurityCenter.encrypt(msg);
            Log.i(TAG, password);
            Log.i(TAG, mSecurityCenter.decrypt(password));
        } catch (RemoteException e) {
            e.printStackTrace();
        }

        Log.i(TAG, "visit ICompute");
        IBinder computeBindedr = binderPool.queryBinder(BinderPool.BINDER_COMPUTE);
        ICompute mCompute = ComputeImpl.asInterface(computeBindedr);
        try {
            Log.i(TAG, mCompute.add(3,5) + "");
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }
}

选择合适的IPC方式