使用AIDL实现Android的跨进程通信

AIDL(Android Interface Definition Language), 即Android接口定义语言. 在Android中, AIDL是跨进程通信的主要实现方式. 我们同样也可以使用AIDL, 实现自己的跨进程方案. 本文介绍AIDL的使用方式.

AIDL

服务端: 创建Service服务监听客户端的请求, 实现AIDL接口.

客户端: 绑定服务端, 调用AIDL的方法.

AIDL接口: 跨进程通信的接口, AIDL的包名需要与项目的包名相同, 默认生成即可.

AIDL支持的数据类型: 基本类型, 字符串类型(String&CharSequence), List, Map, Parcelable, AIDL接口. 共六种.

流程: 客户端注册服务端, 服务端添加新书, 客户端接收, 并提供客户端的查询书数量的接口.

本文源码的GitHub下载地址

AIDL

本文使用自定义的数据类型Book类, 实现Parcelable接口, 具体参考.

 public class Book implements Parcelable {      public int bookId;     public String bookName;      public Book(int bookId, String bookName) {         this.bookId = bookId;         this.bookName = bookName;     }      @Override public int describeContents() {         return 0;     }      @Override public void writeToParcel(Parcel dest, int flags) {         dest.writeInt(bookId);         dest.writeString(bookName);     }      public static final Parcelable.Creator<Book> CREATOR = new Parcelable.Creator<Book>() {         @Override public Book createFromParcel(Parcel source) {             return new Book(source);         }          @Override public Book[] newArray(int size) {             return new Book[size];         }     };      private Book(Parcel source) {         bookId = source.readInt();         bookName = source.readString();     }      @Override public String toString() {         return "ID: " + bookId + ", BookName: " + bookName;     } }

AIDL使用自定义类, 需要声明Parcelable类.

 // IBook.aidl package org.wangchenlong.wcl_aidl_demo;  // Declare any non-default types here with import statements  parcelable Book;

添加AIDL的接口, 用于通知新书到达.

 // IOnNewBookArrivedListener.aidl package org.wangchenlong.wcl_aidl_demo;  // Declare any non-default types here with import statements import org.wangchenlong.wcl_aidl_demo.Book;  interface IOnNewBookArrivedListener {     /**      * 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);      void onNewBookArrived(in Book newBook); }

AIDL文件注释较多, 都是自动生成, 不影响阅读.

核心AIDL类, 书籍管理器, 四个方法, 获取图书列表, 添加书籍, 注册接口, 解注册接口. 注意, 使用其他方法, 需要import导入相应文件.

 // IBookManager.aidl package org.wangchenlong.wcl_aidl_demo;  // Declare any non-default types here with import statements  import org.wangchenlong.wcl_aidl_demo.Book; import org.wangchenlong.wcl_aidl_demo.IOnNewBookArrivedListener;  interface IBookManager {     /**      * 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);     List<Book> getBookList(); // 返回书籍列表     void addBook(in Book book); // 添加书籍     void registerListener(IOnNewBookArrivedListener listener); // 注册接口     void unregisterListener(IOnNewBookArrivedListener listener); // 注册接口 }

所有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.

服务端

服务端通过Binder实现AIDL的IBookManager.Stub接口.

 private Binder mBinder = new IBookManager.Stub() {     @Override public List<Book> getBookList() throws RemoteException {         SystemClock.sleep(5000); // 延迟加载         return mBookList;     }      @Override public void addBook(Book book) throws RemoteException {         mBookList.add(book);     }      @Override     public void registerListener(IOnNewBookArrivedListener listener) throws RemoteException {         mListenerList.register(listener);         int num = mListenerList.beginBroadcast();         mListenerList.finishBroadcast();         Log.e(TAG, "添加完成, 注册接口数: " + num);     }      @Override     public void unregisterListener(IOnNewBookArrivedListener listener) throws RemoteException {         mListenerList.unregister(listener);         int num = mListenerList.beginBroadcast();         mListenerList.finishBroadcast();         Log.e(TAG, "删除完成, 注册接口数: " + num);     } };

服务启动时, 添加两本新书, 并使用线程继续添加.

 @Override public void onCreate() {     super.onCreate();     mBookList.add(new Book(1, "Android"));     mBookList.add(new Book(2, "iOS"));     new Thread(new ServiceWorker()).start(); }

添加书籍, 并发送通知.

 private class ServiceWorker implements Runnable {     @Override public void run() {         while (!mIsServiceDestroyed.get()) {             try {                 Thread.sleep(5000);             } catch (InterruptedException e) {                 e.printStackTrace();             }             num++;             if (num == 5) {                 mIsServiceDestroyed.set(true);             }             Message msg = new Message();             mHandler.sendMessage(msg); // 向Handler发送消息,更新UI         }     } }  private Handler mHandler = new Handler() {     public void handleMessage(Message msg) {         int bookId = 1 + mBookList.size();         Book newBook = new Book(bookId, "新书#" + bookId);         try {             onNewBookArrived(newBook);         } catch (RemoteException e) {             e.printStackTrace();         }     } };

向注册监听的, 发送新书的添加通知.

 private void onNewBookArrived(Book book) throws RemoteException {     mBookList.add(book);     Log.e(TAG, "发送通知的数量: " + mBookList.size());     int num = mListenerList.beginBroadcast();     for (int i = 0; i < num; ++i) {         IOnNewBookArrivedListener listener = mListenerList.getBroadcastItem(i);         Log.e(TAG, "发送通知: " + listener.toString());         listener.onNewBookArrived(book);     }     mListenerList.finishBroadcast(); }

在AndroidManifest中, Service与Activity不在同一进程.

 <!--与主应用不在同一进程中--> <service     android:name=".BookManagerService"     android:process=":remote"/>

客户端

绑定服务和解绑服务, 绑定服务的具体内容, 都是在mConnection中实现.

 @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     mTextView = (TextView) findViewById(R.id.main_tv_book_list); }  @Override protected void onDestroy() {     if (mRemoteBookManager != null && mRemoteBookManager.asBinder().isBinderAlive()) {         try {             Log.e(TAG, "解除注册");             mRemoteBookManager.unregisterListener(mOnNewBookArrivedListener);         } catch (RemoteException e) {             e.printStackTrace();         }     }     unbindService(mConnection);     super.onDestroy(); }

添加内容, 注册监听接口.

 private ServiceConnection mConnection = new ServiceConnection() {     @Override public void onServiceConnected(ComponentName name, IBinder service) {         IBookManager bookManager = IBookManager.Stub.asInterface(service);         try {             mRemoteBookManager = bookManager;             Book newBook = new Book(3, "学姐的故事");             bookManager.addBook(newBook);             new BookListAsyncTask().execute();             bookManager.registerListener(mOnNewBookArrivedListener);         } catch (RemoteException e) {             e.printStackTrace();         }     }      @Override public void onServiceDisconnected(ComponentName name) {         mRemoteBookManager = null;         Log.e(TAG, "绑定结束");     } };

当调用监听接口时, 异步显示图书列表.

 private IOnNewBookArrivedListener mOnNewBookArrivedListener = new IOnNewBookArrivedListener.Stub() {     @Override public void onNewBookArrived(Book newBook) throws RemoteException {         mHandler.obtainMessage(MESSAGE_NEW_BOOK_ARRIVED, newBook).sendToTarget();     } };  private Handler mHandler = new Handler() {     @Override public void handleMessage(Message msg) {         switch (msg.what) {             case MESSAGE_NEW_BOOK_ARRIVED:                 Log.e(TAG, "收到的新书: " + msg.obj);                 new BookListAsyncTask().execute();                 break;             default:                 super.handleMessage(msg);                 break;         }     } };

点击绑定服务按钮, 执行绑定服务. 点击获取图书数量按钮, 获取当前列表的数量.

效果

使用AIDL实现Android的跨进程通信