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.
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
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"/>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
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.
OK, that's all! Enjoy it!