Android下的IPC通信方式

一、Bundle

Android的Activity、Service、Receiver都支持在Intent传递Bundle数据,Bundle实现了Parcelable接口,

所以能很方便的在不同进程之间进行数据传传输.比如A应用打开B应用的某个Activity,如果要传递自定义的类型,

可以继承自Parcelable接口,参考Parcelable的使用方式 Android序列化的几种实现方式

A页面:

public class MainActivity extends AppCompatActivity {
    private final static int OPEN_OTHER_ACTIVITY_REQUEST_CODE = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_main);

	Intent intent = new Intent();
	String packageName = "komine.demos.ipcdemo2";
	String activityName = packageName + ".MainActivity";
	intent.putExtra("msg","来自komine.demos.ipc传递的参数");
	ComponentName componentName = new ComponentName(packageName,activityName);
	intent.setComponent(componentName);

	startActivityForResult(intent,OPEN_OTHER_ACTIVITY_REQUEST_CODE);
    }
  
    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        if(data != null){
            if(requestCode == OPEN_OTHER_ACTIVITY_REQUEST_CODE){
                Toast.makeText(getApplicationContext(),data.getStringExtra("value"),Toast.LENGTH_SHORT).show();
            }
        }
    }
}

B页面:

public class MainActivity extends AppCompatActivity {

    private final static int RESULT_CODE = 0;
    private TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_main);

	textView = findViewById(R.id.tv);
        if(getIntent() != null){
            String msg = getIntent().getStringExtra("msg");
            textView.setText(msg);
        }
    }

    @Override
    public void onBackPressed() {
       Intent intent = new Intent();
       intent.putExtra("value","来自komine.demos.ipcdemo2的MainActivity页面返回的值");
       setResult(RESULT_CODE,intent);

       finish();
    }
}

二、Messenger

1.基本使用

Messenger是基于AIDL的一种轻量化跨进程通信方式,内部是通过Handler进行消息发送的

首先新建一个MessengerService类

public class MessengerService extends Service implements Handler.Callback {

    private static final String TAG = "MessengerService";
    public static final int CLIENT_WHAT = 1;
    public static final int SERVER_WHAT = 2;

    //服务端接收到一条消息就会向客户端发送一条回复消息
    @Override
    public boolean handleMessage(@NonNull Message msg) {
        if (msg.what == CLIENT_WHAT) {
            Log.d(TAG, "收到来自客户端的消息:" + msg.getData());

	    //msg.replyTo是客户端定义的Messenger对象,用来向客户端发送消息
	    Messenger client = msg.replyTo;
            Message replyMessage = Message.obtain(null, SERVER_WHAT);

	    Bundle bundle = new Bundle();
	    bundle.putString("reply", "服务端回复客户端的数据..." + new Date());
	    replyMessage.setData(bundle);

            try {
		//调用客户端的Messenger对象向客户端发送消息
                client.send(replyMessage);
	    } catch (Exception e) {
                e.printStackTrace();
	    }
        }
        return false;
    }

    //服务端的Messenger对象,客户端可以通过onBind中返回的IBinder对象
    //来实例化一个Messenger对象,用来向服务端发送Message,Messenger内部采用
    //的是Message来进行消息传递,所以需要一个Handler对象来进行消息发送
    private final Messenger mMessenger = new Messenger(new Handler(Looper.getMainLooper(),this));

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
	//返回Messenger的Binder对象
        return mMessenger.getBinder();
    }
}

在AndroidManifest.xml注册MessengerService,该服务运行在另外一个进程中,冒号开头表示在当前进程名之前加上完整的包名,

并且该进程为应用的私有进程,不以冒号开头,则表示全局进程,其他可以通过sharedUserId的方式将自己运行在同一个进程中,比如

sharedUserId = "android.uid.system",将自己运行在系统进程中,以取得系统进程的一些权限,以这种方式运行在一起的进程之间

可以互相访问对方的私有数据,比如data目录、files目录,另外签名要保持一致才行,debug版本不需要.

注册MessengerService

<service android:name="komine.demos.messager.MessengerService" android:process=":remote"/>

MainActivity,布局就一个按钮,绑定了sendMsg方法就不贴代码了

public class MainActivity extends AppCompatActivity implements ServiceConnection,Handler.Callback {

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

	//绑定远程Service
	bindService(new Intent(this, MessengerService.class),this,Context.BIND_AUTO_CREATE);
    }

    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        //通过IBinder对象创建一个Messenger实例
	mService = new Messenger(service);
    }

    //点击发送按钮就会向服务端发送一条Message
    public void sendMsg(View view) {
        Message msg = Message.obtain(null,MessengerService.CLIENT_WHAT);

	Bundle data = new Bundle();
	data.putString("msg","hello,this is client");
	msg.setData(data);

	//指定当前消息是那个Messenger对象发送的,该对象就是我们在服务端
	//向客户端发送Message的Messenger对象
	msg.replyTo = mGetReplyMessenger;
        try{
            mService.send(msg);
	}catch (RemoteException e){
            e.printStackTrace();
	}
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {

    }

    //客户端的Messenger对象
    private Messenger mGetReplyMessenger = new Messenger(new Handler(Looper.getMainLooper(),this));

    //处理服务端发送回来的Message
    @Override
    public boolean handleMessage(@NonNull Message msg) {
        if(msg.what == MessengerService.SERVER_WHAT){
            Log.d("client", "收到来自服务端的消息:" + msg.getData().getString("reply"));
    	}
        return false;
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(mService != null && mService.getBinder().isBinderAlive()){
            unbindService(this);
	}
    }
}

客户端输出:

服务端输出:

注意:由于MessengerService是在不同的线程,需要切换进程才能看到对于的日志输出

Messenger是通过Handler来实现消息发送的,而Handler的内部是通过消息队列来维护每一个Message对象,

队列是一个先进先出的数据结构,所以Messenger无法并发处理多个消息,只能一条一条的处理.

2.绑定其他应用的Service

上述代码是客户端和服务端都在同一个应用之内的两个不同进程,如果要绑定其他应用的xxx服务,需要通过显式Intent来绑定,
并且远程Service要设置 exported = "true",不然会抛异常

<service android:name=".MessengerServer" android:exported="true"/>

a.setClassName()方式

intent.setClassName("包名","包名.Service名称");

b.setComponent() 方式

intent.setComponent(new ComponentName("包名","包名.Service名称"));

例如:

Intent intent = new Intent();
intent.setComponent(new ComponentName("komine.demos.messenegerserver","komine.demos.messenegerserver.MessengerServer"));

//网上有说直接在bindService()之前调用startService()开启服务,我试过是无效的,小米Note4x(7.1)可以
//在调用该方法之前,需要在另一端(要绑定的服务所在的应用)开启对应的Service
//测试环境:模拟器和真机(索尼),Android11必要在对应应用开启Service才能绑定成功
bindService(intent, this, Context.BIND_AUTO_CREATE);

注意:在调用bindService()之前,需要远程进程(指要绑定的服务所在的应用)开启要绑定的Service,

不然bindService()不报错,也不会回调onServiceConnected()

三、AIDL

AIDL是Android 接口定义语言,可以通过AIDL在两个进程之间进行IPC通信.

1.基本使用

新建Game.java

public class Game implements Parcelable {
    public String name;

    public Game(String name){
        this.name = name;
    }

    protected Game(Parcel in) {
        name = in.readString();
    }

    public static final Creator<Game> CREATOR = new Creator<Game>() {
        @Override
	public Game createFromParcel(Parcel in) {
            return new Game(in);
        }

        @Override
	public Game[] newArray(int size) {
            return new Game[size];
	}
    };

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(name);
    }
}

新建Game.aidl

可能会提示名称不唯一的错误,不让创建,可以先随便取个名字,然后再重命名,应该是as的bug

Game.aidl 对应 Game.java

// Game.aidl
package komine.demos.ipcdemo3;

// Declare any non-default types here with import statements
//指向Game.java
parcelable Game;

新建IGameShopManager.aidl

// IGameShopManager.aidl
package komine.demos.ipcdemo3;

// Declare any non-default types here with import statements
//引入Game.aild 即使是在同一包名下也需要import
import komine.demos.ipcdemo3.Game;
import komine.demos.ipcdemo3.IDownloadCompleteListener;

interface IGameShopManager {
    boolean buy(float money);
    void download(in IDownloadCompleteListener listener);
    void registerDownloadListener(in IDownloadCompleteListener listener);
    void unregisterDownloadListener(in IDownloadCompleteListener listener);
}

新建IDownloadCompleteListener.aidl

// IDownloadCompleteListener.aidl
package komine.demos.ipcdemo3;

// Declare any non-default types here with import statements
import komine.demos.ipcdemo3.Game;

interface IDownloadCompleteListener {
    void onDownloadCompleted(in Game game);
}

新建EShopManagerService.java

public class EShopManagerService extends Service {

    //Android提供的用于跨进程删除listener的接口,内部维护了一个Map集合,key是IBinder,通过
    //比对key来删除对应的listener,如果不使用这个类,而使用普通的集合,在服务解绑,页面关闭之后,listener也不会
    //移除,可以在循环中不断回调打印日志试试
    private RemoteCallbackList<IDownloadCompleteListener> listeners = new RemoteCallbackList<>();

    private Binder mBinder = new IGameShopManager.Stub() {
        @Override
	public boolean buy(float money) throws RemoteException {
            return money >= 100;
        }

        @Override
	public void download(IDownloadCompleteListener listener) throws RemoteException {
            Game game = new Game("黑暗之魂重置版");
            try {
                //模拟耗时操作
		Thread.sleep(3000);

		//固定写法,从RemoteCallbackList取数据的固定写法
		listeners.beginBroadcast();

                int size = listeners.getRegisteredCallbackCount();

                for (int i = 0;i < size;i++){
                    //Android26+可以使用getRegisteredCallbackItem()方法直接获取
                    listeners.getBroadcastItem(i).onDownloadCompleted(game);
	      	}

                //固定写法
		listeners.finishBroadcast();

	   } catch (InterruptedException e) {
                e.printStackTrace();
	   }
        }

        @Override
	public void registerDownloadListener(IDownloadCompleteListener listener) throws RemoteException {
	    //注册回调接口
            listeners.register(listener);
	}

        @Override
	public void unregisterDownloadListener(IDownloadCompleteListener listener) throws RemoteException {
	    //移除回调接口
            listeners.unregister(listener);
	}
    };

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }
}

注册EShopManagerService

<service android:name=".EShopManagerService" android:process=":remote"/>

MainActivity.java

public class MainActivity extends AppCompatActivity implements ServiceConnection {
    private IGameShopManager mShopManager;

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

	bindService(new Intent(this,EShopManagerService.class),this, Context.BIND_AUTO_CREATE);
    }

    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        mShopManager = IGameShopManager.Stub.asInterface(service);
        try {
	    //注册回调接口
            mShopManager.registerDownloadListener(downloadCompleteListener);
	} catch (RemoteException e) {
            e.printStackTrace();
	}
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {

    }

    public void buy(View view) throws RemoteException {
        boolean buyResult = mShopManager.buy(100);
        if(buyResult){
            Toast.makeText(getApplicationContext(),"购买成功!",Toast.LENGTH_SHORT).show();
	}
    }

    public void download(View view) {
        try{
            mShopManager.download(downloadCompleteListener);
	}catch (Exception e){
            e.printStackTrace();
	}
    }

    private IDownloadCompleteListener downloadCompleteListener = new IDownloadCompleteListener.Stub() {
        @Override
	public void onDownloadCompleted(final Game game) throws RemoteException {
            runOnUiThread(new Runnable() {
                @Override
		public void run() {
                    Toast.makeText(getApplicationContext(),"下载完成:" + game.name,Toast.LENGTH_SHORT).show();
		}
            });
	}
    };

    @Override
    protected void onDestroy() {
        super.onDestroy();
	//如果mShopManager的Binder未被销毁
        if(mShopManager != null && mShopManager.asBinder().isBinderAlive()){
            unbindService(this);
            try {
                mShopManager.unregisterDownloadListener(downloadCompleteListener);
	    } catch (RemoteException e) {
                e.printStackTrace();
	    }
        }
    }
}

---------------------------------2022-04-09 更新----------------------------------

2.AIDL绑定远程服务

绑定过程跟Messenger绑定远程服务是一致的.

首先将前面生成好的aidl文件夹全部拷贝到另一个app(服务端)中,直接复制main/aidl文件夹,粘贴就好了

注意:客户端的aidl 文件夹的包名要和服务端的aidl包名一致,复制后会报错,需要build生成所需的文件.

然后将之前创建的EShopManagerService.java复制到app下的(服务端)MainActivity同级目录下,

在AndroidManifest.xml中注册服务

<service android:name=".EShopManagerService" android:exported="true"/>

然后通过显式Intent绑定到远程Service

客户端绑定服务端Service

Intent intent = new Intent();
intent.setComponent(new ComponentName("包名(应用的包名)","(Service所在文件的包名).服务名称"));

bindService(intent,this, Context.BIND_AUTO_CREATE);

由于是复制粘贴的,包名有可能填错,最不会出错的办法是直接去Service文件的最上方复制package后面的包名

3.AIDL权限验证

默认情况下,我们创建的服务任何人都能绑定,只要知道包名和服务的名称就可以连接,

那么如何添加权限验证呢

3.1 在Service的onBind()方法中验证,只要return null,验证失败的客户端就无法绑定服务

@Nullable
@Override
public IBinder onBind(Intent intent) {
    Boolean noAuthorized = true;
    ...
    ...
    //至于验证方式有很多,比如在AndroidManifest.xml中自定义permission,然后判断是否有声明这个权限
    //调用checkCallingOrSelfPermission()检查是否有权限
    if(!noAuthorized){
        return null;
    }
    return mBinder;
}

服务端AndroidManifest.xml

//申明一个连接到远程Service所需的自定义权限
<permission android:name="komine.demos.messenegerserver.EShopManagerService"/>

...
...
//在Service上指定android:permission:komine.demos.messenegerserver.EShopManagerService
<service android:name="komine.demos.ipcdemo3.EShopManagerService" android:exported="true" android:permission="komine.demos.messenegerserver.EShopManagerService"/>

客户端必须显式声明这个权限,不然会抛权限拒绝的异常

客户端AndroidManifest.xml

//komine.demos.messenegerserver.EShopManagerService 在服务端申明的自定义权限
<uses-permission android:name="komine.demos.messenegerserver.EShopManagerService"/>

3.2 在服务端的onTransact()验证

在Service中重写onTransact()方法,然后进行验证

private Binder mBinder = new IGameShopManager.Stub() {
    ...
    ...
    @Override
    public boolean onTransact(int code, Parcel data, Parcel reply, int flags) throws RemoteException {
	//验证方式按自己需求进行选择,返回false表示验证失败
        return super.onTransact(code, data, reply, flags);
}

四、ContentProvider

ContentProvider是Android中提供用于不同应用之间进行数据共享的方式.

1.基本使用

使用很简单,只需要新建一个类继承自ContentProvider即可

public class MyContentProvider extends ContentProvider {
    private final static String TAG = "MyContentProvider";

    @Override
    public boolean onCreate() {
        Log.d(TAG,"onCreate...");
        return false;
    }

    @Nullable
    @Override
    public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection,     @Nullable String[] selectionArgs, @Nullable String sortOrder) {
        Log.d(TAG,"query " + Thread.currentThread().getName());
        return null;
    }

    @Nullable
    @Override
    public String getType(@NonNull Uri uri) {
        return "getType";
    }

    @Nullable
    @Override
    public Uri insert(@NonNull Uri uri, @Nullable ContentValues values) {
        Log.d(TAG,"insert" + Thread.currentThread().getName());
        return null;
    }

    @Override
    public int delete(@NonNull Uri uri, @Nullable String selection, @Nullable String[] selectionArgs) {
        Log.d(TAG,"delete" + Thread.currentThread().getName());
        return 0;
    }

    @Override
    public int update(@NonNull Uri uri, @Nullable ContentValues values, @Nullable String selection, @Nullable String[] selectionArgs) {
        Log.d(TAG,"update" + Thread.currentThread().getName());
        return 0;
    }
}

然后在AndroidManifest.xml的application标签下注册

<provider
    android:authorities="komine.demos.ipcdemo4.provider"
    android:exported="true"
    android:name=".MyContentProvider"/>

接下来就能在其他应用中访问

public class MainActivity extends AppCompatActivity{

    private Messenger mService;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_main);
	//authorities:其他应用的provider中定义的authorities值
	//uri = content:// + authorities
	Uri uri = Uri.parse("content://komine.demos.ipcdemo4.provider");
	getContentResolver().query(uri,null,null,null,null);
	getContentResolver().insert(uri,null);
	getContentResolver().delete(uri,null,null);
	getContentResolver().update(uri,null,null,null);
    }
}

Android11+ 更改了应用之间交互的方式,需要在AndroidManifest.xml中添加queries标签,然后在其中添加目标应用的包名,才能访问到目标应用提供的ContentProvider.

放在manifest节点

<queries>
    <package android:name="komine.demos.ipcdemo4" />
</queries>