08 Service通信

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一、应用内通信

1、启动Service并传递数据

启动一个Service并且向该Service传递数据:

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Intent intent = new Intent(this, MyService.class);
intent.putExtra("data", mEditText.getText().toString().trim());
startService(intent);

MyService接收数据：

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private String data = "MyService default info";
@Override
public int onStartCommand(Intent intent, int flags, int startId) { 
    data = intent.getStringExtra("data");
    return super.onStartCommand(intent, flags, startId);
}

2、绑定Service进行通信——>

与被绑定的Service进行通信，首先自定义一个Binder的实现类，拥有setData(String data)方法，并在onBind方法中返回自定义类的对象：

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public class MyService extends Service {
    private String data = "MyService default info";
    @Override
    public IBinder onBind(Intent intent) {
        return new MyBinder();
    }
    public class MyBinder extends Binder {
        public void setData(String data) {
            MyService.this.data = data;
        }
    }
    ...
}

在ServiceConnection实现类中onServiceConnected方法里获取服务绑定成功时返回的对象

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public class MainActivity extends AppCompatActivity implements View.OnClickListener, ServiceConnection {
    private MyService.MyBinder mMyBinder;
    ...
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        mMyBinder = (MyService.MyBinder) service;
    }
}

然后MainActivity就可以实时的想MyService同步数据了：

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if (mMyBinder != null)
    mMyBinder.setData(mEditText.getText().toString().trim());

输出日志

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I/System.out: MyService onCreate
I/System.out: MyService default info
I/System.out: MyService default info
I/System.out: MyService default info
I/System.out: MyService default info
I/System.out: MainActivity say something
I/System.out: MainActivity say something
I/System.out: MainActivity say something
I/System.out: MyService onDestroy

3、绑定Service进行通信<——

侦听被绑定的Service的内部状态，需要借助回调接口。首先定义回调接口并设置set(callBack)方法：

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public class MyService extends Service {
    private CallBack mCallBack;
    public void setCallBack(CallBack callBack) {
        mCallBack = callBack;
    }
    public static interface CallBack {
        public void onDataChange(String data);
    }
    ...
}

自定义类MyBinder中增加一个方法，返回当前Service的对象，以便于外部客户端调用set(callBack)方法

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public class MyBinder extends Binder {
    ...
    public MyService getService() {
        return MyService.this;
    }
}

在Service中将状态信息通过回调接口通知外界

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i++;
if (mCallBack != null)
    mCallBack.onDataChange(i + " " + data);

ServiceConnection的实现类（此处为MainActivity）在onServiceConnected方法中获取Service对象，并将自定义的回调接口告知Service：

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@Override
public void onServiceConnected(ComponentName name, IBinder service) {
    mMyBinder = (MyService.MyBinder) service;
    mMyBinder.getService().setCallBack(new MyService.CallBack() {
        @Override
        public void onDataChange(String data) {
            Message msg = new Message();
            Bundle bundle = new Bundle();
            bundle.putString("data", data);
            msg.setData(bundle);
            mHandler.sendMessage(msg);
        }
    });
}

借助Handler，将数据同步到TextView上：

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private Handler mHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        super.handleMessage(msg);
        mTextView.setText(msg.getData().getString("data"));
    }
};

二、跨应用通信——AIDL

1、跨应用启动Service

从Android5.0以后，只能通过显示Intent来启动服务。

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package com.xianxiaotao.firstapp;
public class MainActivity extends AppCompatActivity {
    private Intent mIntent;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
        mIntent = new Intent();
        mIntent.setComponent(new ComponentName("com.xianxiaotao.secondapp", "com.xianxiaotao.secondapp.AppService"));
        startService(mIntent)
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        stopService(mIntent);
    }
}

2、跨应用绑定Service

新建AIDL文件：New -> AIDL -> AIDL File -> IAppServiceRemoteBinder.aidl

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package com.xianxiaotao.secondapp;
interface IAppServiceRemoteBinder {
    void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, String aString);
}

在Service里实现该接口：

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package com.xianxiaotao.secondapp;
public class AppService extends Service {
    
    ...
    @Override
    public IBinder onBind(Intent intent) {
        return new IAppServiceRemoteBinder.Stub() {
            @Override
            public void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, String aString) {
                // TODO
            }
        };
    }
}

在第一个应用中绑定服务和解除绑定服务：

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bindService(mIntent, this, Context.BIND_AUTO_CREATE);
unbindService(this);

3、跨应用绑定Service并通信

在IAppServiceRemoteBinder接口中新增setData方法

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interface IAppServiceRemoteBinder {
    void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, String aString);
    void setData(String data);
}

其子类需要实现该方法

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@Override
public IBinder onBind(Intent intent) {
    return new IAppServiceRemoteBinder.Stub() {
        @Override
        public void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, String aString) {
            // TODO
        }
        @Override
        public void setData(String data) throws RemoteException {
            AppService.this.data = data;
        }
    };
}

在第一个应用里创同样的IAppServiceRemoteBinder.aidl文件，注意包名也要一致。

  • firstApp -> New -> Folder -> AIDL Folder
  • aidl -> New -> Package -> com.xianxiaotao.secondapp -> OK
  • 在该文件夹里创建同样的IAppServiceRemoteBinder.aidl文件，测试时可以直接复制粘贴。
    上述操作执行完毕后，该应用绑定secondapp的AppService时，可以获取到IBinder的实例了。
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    private IAppServiceRemoteBinder binder = null;
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        // 此处不能用强制类型转换，虽然类名相同，但两个类在内存中地址不一样
        binder = IAppServiceRemoteBinder.Stub.asInterface(service);
    }
    ...
    if (binder != null) {
        try {
            binder.setData(mEditText.getText().toString().trim());
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }