Android AIDL 的简单使用

本文完整项目

链接：https://download.youkuaiyun.com/download/yancr/12739358
链接(老版本)：https://download.youkuaiyun.com/download/yancr/11082932

目标

1. A 应用向 B 应用发送两个数字
2. B 应用展示两个数字的和
3. A 应用向B应用获取两个数字的和

项目结构

运行截图

1. 应用A初始界面
   
2. 应用B初始界面
   
3. 应用B生成随机数并发送
   
4. 应用A接收到随机数并计算和
   
5. 应用B获取应用A的计算结果
   

实现

以下未列出的文件，未做特殊修改。代码如果有不规范请不要在意。
没写很多注释，不过应该很容易看懂的。

----app1

文件1，AIDL 接口文件，app2 通过调用 app1 提供的接口与 app1 进行通信。

接口中支持的变量类型只有 int、long、char、boolean、double、String、CharSequence、List Map must be ArrayList HashMap、Parcelable。

若要其他类型需要使用 import 进行声明，如 import com.ycr.aidlserver.Person，而 public class Person implements Parcelable。

// SendTwoNumbersManager.aidl
package com.ycr.app1;

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

interface SendTwoNumbersManager {
    /**
     * Demonstrates some basic types that you can use as parameters
     * and return values in AIDL.
     */
    void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat,
            double aDouble, String aString);
    //app1 gives the interface to app2, with which app2 send two numbers to app1
    void sendTwoNumbers(int a1, int a2);
    //app1 gives the interface to app2, with which app2 is able to get plus result from app1
    int getResult();
}

文件2，app1 的主界面，提供一个 TextView 进行数据的展示。
为了 Activity 与 Service 的通信，使用了 LiveData，LiveData 作为 ViewModel 的成员变量存在。

package com.ycr.app1;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;
import androidx.lifecycle.Observer;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    private TextView iTV;
    private ServiceToActivityViewModel viewModel;
    private Observer<Integer> newValueObserver;

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

        iTV = findViewById(R.id.iTV);
        iTV.setOnClickListener(this);

        viewModel = ServiceToActivityViewModel.get(getApplication());
        newValueObserver = new Observer<Integer>() {
            @Override
            public void onChanged(Integer integer) {
                Log.e("app1", integer + "");
                iTV.setText(String.valueOf(integer));
            }
        };
        viewModel.getNewValue().observe(this, newValueObserver);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        viewModel.getNewValue().removeObserver(newValueObserver);
    }

    @Override
    public void onClick(View v) {
    }
}

文件3，app1 提供给 app2 使用的服务，服务中使用匿名类对 AIDL 接口进行了实现。

package com.ycr.app1;

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

public class GetTwoNumbersService extends Service {
    private int result;
    private ServiceToActivityViewModel viewModel;
    private final SendTwoNumbersManager.Stub sendTwoNumbersManager = new SendTwoNumbersManager.Stub() {
        @Override
        public void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, String aString) { }

        @Override
        public void sendTwoNumbers(int a1, int a2) {
            Log.e("app1", "add");
            synchronized (this) {
                result = a1 + a2;
                viewModel.getNewValue().postValue(result);
            }
        }

        @Override
        public int getResult() {
            return result;
        }
    };

    public GetTwoNumbersService() {
    }
    @Override
    public IBinder onBind(Intent intent) {
        if("com.ycr.app1".equals(intent.getAction())) {
            if(viewModel == null) {
                Log.e("app2-app1", getApplication().getPackageName());
                viewModel = ServiceToActivityViewModel.get(getApplication());
            }
            return sendTwoNumbersManager;
        }
        return null;
    }
}

文件4，ViewModel，用于存放 LiveData，Activity 中注册 Observer，当Service 使用 set 改变LiveData，则 Activity 中的 Observer 会收到 onChanged 回调。

package com.ycr.app1;

import android.app.Application;

import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.ViewModel;
import androidx.lifecycle.ViewModelProvider;

public class ServiceToActivityViewModel extends ViewModel {
    private static ServiceToActivityViewModel viewModel = null;
    private MutableLiveData<Integer> newValue;

    public MutableLiveData<Integer> getNewValue() {
        if(newValue == null) {
            newValue = new MutableLiveData<>();
        }
        return newValue;
    }
    synchronized static ServiceToActivityViewModel get(Application application) {
        if(viewModel == null) {
            viewModel = ViewModelProvider.AndroidViewModelFactory.getInstance(application).create(ServiceToActivityViewModel.class);
        }
        return viewModel;
    }
}

文件5，Manifest 文件，主要修改了 启动 (bind) 服务的action 和 category。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.ycr.app1">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <service
            android:name=".GetTwoNumbersService"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.ycr.app1" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </service>

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

----app2

文件1，app2 的主界面，通过 bind 连接到 app1 的服务，而后 app1 返回的 IBinder 接口 即是 AIDL 接口。app2可以通过这个接口与 app1 进行通信。

package com.ycr.app2;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.os.RemoteException;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.ycr.app1.SendTwoNumbersManager;

import java.util.Random;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    private TextView iTV;
    private Button getResultBtn;
    private Random random;
    private SendTwoNumbersManager sendMsendTwoNumbersManagernager;
    private boolean isConnect;
    private ServiceConnection serviceConnection;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        random = new Random(System.currentTimeMillis());
        isConnect = false;

        iTV = findViewById(R.id.iTV);
        iTV.setOnClickListener(this);

        getResultBtn = findViewById(R.id.getResultBtn);
        getResultBtn.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        if(v.equals(iTV)) {
            if (!isConnect) {
                iTV.setText("Not Connected. Connecting.");
                serviceConnection = new ServiceConnection() {
                    @Override
                    public void onServiceConnected(ComponentName name, IBinder service) {
                        isConnect = true;
                        sendMsendTwoNumbersManagernager = SendTwoNumbersManager.Stub.asInterface(service);
                        iTV.setText("Connected");
                    }

                    @Override
                    public void onServiceDisconnected(ComponentName name) {
                        isConnect = false;
                    }
                };
                Intent intent = new Intent();
                intent.setPackage("com.ycr.app1");
                intent.setAction("com.ycr.app1");
                bindService(intent, serviceConnection, BIND_AUTO_CREATE);
            }
            if (isConnect) {
                int a1 = random.nextInt(20);
                int a2 = random.nextInt(20);
                iTV.setText(a1 + " + " + a2);
                try {
                    sendMsendTwoNumbersManagernager.sendTwoNumbers(a1, a2);
                } catch (RemoteException e) {
                    e.printStackTrace();
                }
            }
        } else if(v.equals(getResultBtn)) {
            int result = 0;
            if(sendMsendTwoNumbersManagernager != null && isConnect) {
                try {
                    result = sendMsendTwoNumbersManagernager.getResult();
                } catch (RemoteException e) {
                    e.printStackTrace();
                }
            }
            iTV.setText(String.valueOf(result));
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(isConnect) {
            unbindService(serviceConnection);
        }
    }
}