概述

AIDL是一个缩写，全称是Android Interface Definition Language，也就是Android接口定义语言，它是用来实现进程间通讯的，本文使用AIDL写一个小demo来实现夸进程间通讯

AIDL介绍

文件类型：用aidl书写的文件的后缀是.aidl
数据类型：基本类型, 字符串类型(String&CharSequence), List, Map, Parcelable, AIDL接口共六种
AIDL文件类型：1：定义parcelable对象，以供其他AIDL文件使用AIDL中非默认支持的数据类型的，2：用来定义方法接口，用来进行夸进程间通讯使用的

小Demo

本文写的一个小demo，服务端用来提供音乐列表，客户端从服务端拉取音乐列表
demo地址：github.com/syg13579/an…

AIDL

首先定义一个音乐的类型Music类，并实现Parcelable接口

public class Music implements Parcelable {
    public String name; //书名
    public String author; //作者


    public Music(String name ,String author){
        this.name = name;
        this.author = author;
    }

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

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

    public Music() {
    }

    protected Music(Parcel in) {
        this.name = in.readString();
        this.author = in.readString();
    }

    public static final Parcelable.Creator<Music> CREATOR = new Parcelable.Creator<Music>() {
        @Override
        public Music createFromParcel(Parcel source) {
            return new Music(source);
        }

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

    @Override
    public String toString() {
        return "音乐名称："+name +"  歌手："+author;
    }
}

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然后看相关的aidl的music类

package rock.pp.com.aidl_demo;

parcelable Music;

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注意：aidl的Music和java的Music的包名必须一致

下面添加AIDL的接口，是一个接口类用于监听新音乐的到达的接口

package rock.pp.com.aidl_demo;

import rock.pp.com.aidl_demo.Music;

interface INewMusicArrivedListener {
    void onNewBookArrived(in Music newMusic);
}

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下面是音乐管理类的AIDL接口,用来管理音乐的，这个类是进程间通讯的核心类，主要有四个方法，1：获取音乐类别 2：添加音乐 3：注册接口 4：注销接口


package rock.pp.com.aidl_demo;

// Declare any non-default types here with import statements
import rock.pp.com.aidl_demo.Music;
import rock.pp.com.aidl_demo.INewMusicArrivedListener;

interface IMusicManager {

    List<Music> getMusicList(); // 返回书籍列表
    void addMusic(in Music music); // 添加书籍

    void registerListener(INewMusicArrivedListener listener); // 注册接口
    void unregisterListener(INewMusicArrivedListener listener); // 注销接口

}
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所有的自定义的参数都需要标注参数方向, in表示输入类型, out表示输出类型, inout表示输入输出类型. out与inout的开销较大, 不能统一使用高级方向.

AIDL文件通过编译会自动生成对应的java文件，服务端和客户端操作的就是对应的java文件

如上图所以，蓝色框内是我们定义的AIDL文件，红色框内是自动编译生成的java文件

服务端

下面我们看下服务端的代码

/**
 * 音乐管理的服务类
 */
public class MusicManagerService extends Service {

    private static final String TAG =  MusicManagerService.class.getSimpleName();

    private ArrayList<Music> mMusicList = new ArrayList<>();  //生成的音乐列表
    private List<INewMusicArrivedListener> mListenerList = new ArrayList<>(); //客户端注册的接口列表
    private boolean isServiceDestroy = false; //当前服务是否结束
    private int num = 0;

    /**
     * 解绑服务
     * @param conn
     */
    @Override
    public void unbindService(ServiceConnection conn) {
        super.unbindService(conn);
        Log.e(TAG,"unbindService-----");
    }
    
    /**
     * 服务端通过Binder实现AIDL的IMusicManager.Stub接口
     * 这个类需要实现IMusicManager相关的抽象方法
     */
    private Binder mBinder = new IMusicManager.Stub() {
        @Override
        public List<Music> getMusicList() throws RemoteException {
            SystemClock.sleep(1000); // 延迟加载
            return mMusicList;
        }

        @Override
        public void addMusic(Music music) throws RemoteException {
            mMusicList.add(music);
        }

        @Override
        public void registerListener(INewMusicArrivedListener listener) throws RemoteException {
            mListenerList.add(listener);
            int num = mListenerList.size();
            Log.e(TAG, "添加完成, 注册接口数: " + num);
        }

        @Override
        public void unregisterListener(INewMusicArrivedListener listener) throws RemoteException {
            mListenerList.add(listener);
            int num = mListenerList.size();
            Log.e(TAG, "添加完成, 注册接口数: " + num);
        }
    };


    //新音乐到达后给客户端发送相关通知
    private void onNewMusicArrived(Music music) throws Exception {
        mMusicList.add(music);
        Log.e(TAG, "发送通知的数量: " + mMusicList.size());
        int num = mListenerList.size();
        for (int i = 0; i < num; ++i) {
            INewMusicArrivedListener listener = mListenerList.get(i);
            listener.onNewBookArrived(music);
        }
        for (Music b : mMusicList){
            Log.e(TAG,b.name+"  "+b.author);
        }
    }

    @Override public void onCreate() {
        super.onCreate();
        Log.e(TAG,"onCreate-------------");
        //首先添加两首歌曲
        mMusicList.add(new Music("《封锁我一生》", "王杰"));
        mMusicList.add(new Music("《稻香》", "周杰伦"));
        //音乐制造机器
        new Thread(new ServiceWorker()).start();
    }

    @Override public void onDestroy() {
        isServiceDestroy = true;
        super.onDestroy();
        Log.e(TAG,"onDestroy-----");
    }
    
    //音乐制造机
    //每5秒生产一首音乐
    private class ServiceWorker implements Runnable {
        @Override public void run() {
            while (!isServiceDestroy) {
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                num++;
                if (num == 5) {
                    isServiceDestroy= true;
                }
                Message msg = new Message();
                mHandler.sendMessage(msg); // 向Handler发送消息,更新UI
            }
        }
    }

    private Handler mHandler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            int id = 1 + mMusicList.size();
            Music music = new Music("《张学友——新歌》"+id, "张学友");
            try {
                onNewMusicArrived(music);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    };

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

}
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如上所示，我们通过IMusicManager.Stub生成进程间通讯的binder类，然后新启一个线程动态生成音乐，然后告知客户端

客户端

下面我们看下客户端的代码

 private TextView music_list;

    private IMusicManager mRemoteMusicManager; //音乐管理类  通过aidl文件编译生成的java类


    //监听新音乐的到达的接口
    private INewMusicArrivedListener musicArrivedListener = new INewMusicArrivedListener.Stub() {
        /**
         * 服务端有新音乐生成
         * @param newMusic
         * @throws RemoteException
         */
        @Override
        public void onNewBookArrived(Music newMusic) throws RemoteException {
            mHandler.obtainMessage(MESSAGE_ARRIVED, newMusic ).sendToTarget();
        }
    };

    private Handler mHandler = new Handler() {
        @Override public void handleMessage(Message msg) {
            switch (msg.what) {
                case MESSAGE_ARRIVED:
                    Log.e(TAG, "收到的新书: " + msg.obj);
                    new BookListAsyncTask().execute();
                    break;
                default:
                    super.handleMessage(msg);
                    break;
            }
        }
    };


    //绑定服务时的链接参数
    private ServiceConnection mConnection = new ServiceConnection() {
        @Override public void onServiceConnected(ComponentName name, IBinder service) {
            IMusicManager musicManager = IMusicManager.Stub.asInterface(service);

            try {
                mRemoteMusicManager = musicManager;
                Music newMusic = new Music("《客户端音乐》", "rock");
                musicManager.addMusic(newMusic);
                musicManager.registerListener(musicArrivedListener);
                new BookListAsyncTask().execute();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override public void onServiceDisconnected(ComponentName name) {
            mRemoteMusicManager = null;
            Log.e(TAG, "绑定结束");
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        music_list = findViewById(R.id.music_list);
    }

    /**
     * 获取music列表
     *
     * @param view 视图
     */
    public void getMusicList(View view) {
        if (mRemoteMusicManager !=null){
            List<Music> list = null;
            try {
                list = mRemoteMusicManager.getMusicList();
            }catch (Exception e){

            }
            if (list!=null){
                String content = "";
                for (int i = 0; i < list.size(); ++i) {
                    content += list.get(i).toString() + "\n";
                }
                music_list.setText(content);
            }
        }
        Toast.makeText(getApplicationContext(), "正在获取中...", Toast.LENGTH_SHORT).show();
    }


    /**
     * 绑定服务按钮的点击事件
     *
     * @param view 视图
     */
    public void bindService(View view) {
        Intent intent = new Intent(this, MusicManagerService.class);
        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
    }


    /**
     * 解绑服务
     */
    public void unbindService(View view){
        unbindService(mConnection);
    }


    private class BookListAsyncTask extends AsyncTask<Void, Void, List<Music>> {
        @Override
        protected List<Music> doInBackground(Void... params) {
            List<Music> list = null;
            try {
                list = mRemoteMusicManager.getMusicList();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
            return list;
        }

        @Override
        protected void onPostExecute(List<Music> musicList) {
            String content = "";
            for (int i = 0; i < musicList.size(); ++i) {
                content += musicList.get(i).toString() + "\n";
            }
            music_list.setText(content);
        }
    }
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客户端代码如上，我们绑定一个服务，然后注册一个新音乐到达的接口，当服务端有新音乐生成的时候就会触发这个接口