使用AIDL实现Android的跨进程通信
gztzq
8年前
<p><strong>AIDL(Android Interface Definition Language)</strong>, 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.</p> <p style="text-align: center;"><img alt="使用AIDL实现Android的跨进程通信" src="https://simg.open-open.com/show/6034a0757457f1ae9eae6e0d054bac6e.jpg"></p> <p style="text-align: center;">AIDL</p> <p>服务端: 创建Service服务监听客户端的请求, 实现AIDL接口.</p> <p>客户端: 绑定服务端, 调用AIDL的方法.</p> <p>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.</p> <blockquote> <p>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.</p> </blockquote> <p><strong>流程</strong>: 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.</p> <p>本文源码的GitHub<a href="/misc/goto?guid=4959674332251497097">下载地址</a></p> <h2>AIDL</h2> <p>本文使用自定义的数据类型<strong>Book</strong>类, 实现Parcelable接口, 具体<a href="/misc/goto?guid=4959672537061666462">参考</a>.</p> <pre> <code class="language-java">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; } }</code></pre> <p>AIDL使用自定义类, 需要声明Parcelable类.</p> <pre> <code class="language-java">// IBook.aidl package org.wangchenlong.wcl_aidl_demo; // Declare any non-default types here with import statements parcelable Book;</code></pre> <p>添加AIDL的接口, 用于通知新书到达.</p> <pre> <code class="language-java">// 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); }</code></pre> <blockquote> <p>AIDL文件注释较多, 都是自动生成, 不影响阅读.</p> </blockquote> <p>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<strong>import</strong>导入相应文件.</p> <pre> <code class="language-java">// 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 }</code></pre> <blockquote> <p>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.</p> </blockquote> <h2>服务端</h2> <p>服务端通过<strong>Binder</strong>实现AIDL的<code>IBookManager.Stub</code>接口.</p> <pre> <code class="language-java">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); } };</code></pre> <p>服务启动时, 添加两本新书, 并使用线程继续添加.</p> <pre> <code class="language-java">@Override public void onCreate() { super.onCreate(); mBookList.add(new Book(1, "Android")); mBookList.add(new Book(2, "iOS")); new Thread(new ServiceWorker()).start(); }</code></pre> <p>添加书籍, 并发送通知.</p> <pre> <code class="language-java">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(); } } };</code></pre> <p>向注册监听的, 发送新书的添加通知.</p> <pre> <code class="language-java">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(); }</code></pre> <p>在AndroidManifest中, Service与Activity不在同一进程.</p> <pre> <code class="language-java"><!--与主应用不在同一进程中--> <service android:name=".BookManagerService" android:process=":remote"/></code></pre> <h2>客户端</h2> <p>绑定服务和解绑服务, 绑定服务的具体内容, 都是在<code>mConnection</code>中实现.</p> <pre> <code class="language-java">@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(); }</code></pre> <p>添加内容, 注册监听接口.</p> <pre> <code class="language-java">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"); } };</code></pre> <p>当调用监听接口时, 异步显示图书列表.</p> <pre> <code class="language-java">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; } } };</code></pre> <p>点击<code>绑定服务</code>按钮, 执行绑定服务. 点击<code>获取图书数量</code>按钮, 获取当前列表的数量.</p> <p>效果</p> <p><img alt="使用AIDL实现Android的跨进程通信" src="https://simg.open-open.com/show/2afcebd1cc2c0217800f017fa9ff6683.gif"></p> <p>效果</p> <p>Android跨进程通信比较复杂, 但是意义重大, 目前常用的动态加载框架都需要处理跨进程通信等问题, 熟练基本原理, 掌握使用方式.</p> <p>OK, that's all! Enjoy it!</p> <p>文／<a href="/misc/goto?guid=4959674332373165653">SpikeKing</a>（简书）<br> </p> <p> </p>