单向消息分发工具，用于简化 Handler 与 Messenger 的使用，以及简化 MediaSession 的 CustomAction 和 SessionEvent 的使用。
第 1 步：在你的项目的根目录下的 build.gradle 文件中添加以下配置：
allprojects {
repositories {
// ...
maven { url 'https://jitpack.io' }
}
}第 2 步：添加依赖
dependencies {
implementation 'com.github.jrfeng.channel-helper:helper:1.2.7'
implementation 'com.github.jrfeng.channel-helper:pipe:1.2.7'
annotationProcessor 'com.github.jrfeng.channel-helper:processor:1.2.7'
}第 1 步：创建一个接口，如下例所示：
注意：接口中方法的返回值类型必须是 void。
public interface Duck {
void eat();
void quack(int voice);
void swing(int speed);
void fly(int high, int speed);
}第 2 步：使用 @Channel 注解标注创建的接口，如下例所示：
import channel.helper.Channel;
@Channel
public interface Duck {
void eat();
void quack(int voice);
void swing(int speed);
void fly(int high, int speed);
}第 3 步：使用 ChannelHelper 工具类创建一个 emitter 和一个 dispatcher。
ChannelHelper 的工厂方法：
public final class ChannelHelper {
...
// Emitter 工厂
public static <T> T newEmitter(Class<T> clazz, Emitter pipe) {...}
// Dispatcher 工厂
// 需要持有 receiver 的一个强引用
public static <T> Dispatcher newDispatcher(Class<T> clazz, T receiver) {...}
}注意： channel-helper 使用弱引用来避免内存泄露，因此需要持有 receiver 的一个强引用
例 1：与 HandlerPipe 配合使用
// 需要持有 receiver 的一个强引用
private Duck mReceiver = new Duck() {
@Override
public void eat() {
Log.d("App", "eat");
}
@Override
public void quack(int voice) {
Log.d("App", "quack: {voice:" + voice + "}");
}
@Override
public void swing(int speed) {
Log.d("App", "swing: {speed:" + speed + "}");
}
@Override
public void fly(int high, int speed) {
Log.d("App", "fly: {high:" + high + ", speed:" + speed + "}");
}
};
...
Dispatcher duckDispatcher = ChannelHelper.newDispatcher(Duck.class, mReceiver);
Duck emitter = ChannelHelper.newEmitter(Duck.class, new HandlerPipe(duckDispatcher));
emitter.eat(); // 输出: eat
emitter.quack(8); // 输出: quack: {voice:8}
emitter.fly(5, 12); // 输出: fly: {high:5, speed:12}
emitter.swing(7); // 输出: swing: {speed:12}例 2：与 MessengerPipe 配合使用，用于 IPC
Service：
public class TestService extends Service {
private MessengerPipe mMessengerPipe;
private Duck mReceiver;
@Override
public void onCreate() {
super.onCreate();
...
// 需要持有 receiver 的一个强引用
mReceiver = new Duck() {
@Override
public void eat() {
Log.d("App", "eat");
}
@Override
public void quack(int voice) {
Log.d("App", "quack: {voice:" + voice + "}");
}
@Override
public void swing(int speed) {
Log.d("App", "swing: {speed:" + speed + "}");
}
@Override
public void fly(int high, int speed) {
Log.d("App", "fly: {high:" + high + ", speed:" + speed + "}");
}
};
Dispacher dispatcher = ChannelHelper.newDispatcher(Duck.class, mReceiver);
mMessengerPipe = new MessengerPipe(dispatcher);
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return mMessengerPipe.getBinder();
}
}ServiceConnection：
public class TestServiceConnection implements ServiceConnection {
private MessengerPipe mMessengerPipe;
private Duck mEmitter;
private boolean mConnected;
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
mMessengerPipe = new MessengerPipe(service);
mEmitter = ChannelHelper.newEmitter(Duck.class, mMessengerPipe);
mConnected = true;
test();
}
@Override
public void onServiceDisconnected(ComponentName name) {
// ...
}
private void test() {
if (!mConnected) {
return;
}
mEmitter.eat();
mEmitter.quack(8);
mEmitter.fly(5, 12);
mEmitter.swing(7);
}
}注意：如果你使用 MessengerPipe 用于进程间通信，请确保接口中方法的参数类型满足 Parcel.writeValue(Object) 的要求。
CustomActionPipe：帮助处理 custom action.SessionEventPipe：帮助处理 session event.
CustomActionPipe 示例：
// 发送端
CustomActionPipe pipe = new CustomActionPipe(mTransportControls);
Duck emitter = ChannelHelper.newEmitter(Duck.class, pipe);
emitter.eat();
emitter.quack(8);
emitter.fly(5, 12);
emitter.swing(7);
// 接收端：MediaSessionCompat.Callback
public class Callback extends MediaSessionCompat.Callback {
private CustomActionPipe mPipe;
private Duck mReceiver;
public Callback() {
// 需要持有 receiver 的一个强引用
mReceiver = new Duck() {
@Override
public void eat() {
Log.d("App", "eat");
}
@Override
public void quack(int voice) {
Log.d("App", "quack: {voice:" + voice + "}");
}
@Override
public void swing(int speed) {
Log.d("App", "swing: {speed:" + speed + "}");
}
@Override
public void fly(int high, int speed) {
Log.d("App", "fly: {high:" + high + ", speed:" + speed + "}");
}
};
Dispacher dispatcher = ChannelHelper.newDispatcher(Duck.class, mReceiver);
mPipe = new CustomActionPipe(dispatcher);
}
...
@Override
public void onCustomAction(String action, Bundle extras) {
mPipe.dispatch(action, extras);
}
}SessionEventPipe 示例：
// 发送端
SessionEventPipe pipe = new SessionEventPipe(mMediaSessionCompat);
Duck emitter = ChannelHelper.newEmitter(Duck.class, pipe);
emitter.eat();
emitter.quack(8);
emitter.fly(5, 12);
emitter.swing(7);
// 接收端：MediaControllerCompat.Callback
public class Callback extends MediaControllerCompat.Callback {
private SessionEventPipe mPipe;
private Duck mReceiver;
public Callback() {
// 需要持有 receiver 的一个强引用
mReceiver = new Duck() {
@Override
public void eat() {
Log.d("App", "eat");
}
@Override
public void quack(int voice) {
Log.d("App", "quack: {voice:" + voice + "}");
}
@Override
public void swing(int speed) {
Log.d("App", "swing: {speed:" + speed + "}");
}
@Override
public void fly(int high, int speed) {
Log.d("App", "fly: {high:" + high + ", speed:" + speed + "}");
}
};
Dispacher dispatcher = ChannelHelper.newDispatcher(Duck.class, mReceiver);
mPipe = new SessionEventPipe(dispatcher);
}
...
@Override
public void onSessionEvent(String event, Bundle extras) {
mPipe.dispatch(event, extras);
}
}可以使用 @UseOrdinal 注解标记一个枚举类型的参数，这将使用枚举值的序数整数替换枚举值。这对 IPC 很有帮助，因为 Parcel 不支持枚举类型。
例：
public enum Color {
REG, GREEN, BLUE
}
public interface Foo {
void setColor(@UseOrdinal Color color);
}可以使用静态方法 DispatcherUtil.merge(Dispacher dispatcher, Dispacher... others) 合并多个 dispatcher。这样的话，你就可以在多个接口之间共享同一个 pipe 实例（例如 HandlerPipe），而不需要为每个接口创建一个新的 pipe 实例。
例：
// 需要持有 receiver 的一个强引用
private Duck mDuckReceiver = new Duck() {/*...*/};
private Chicken mChickenReceiver = new Chicken() {/*...*/});
...
// 合并多个 dispatcher
Dispatcher mergeDispatcher = DispatcherUtil.merge(
ChannelHelper.newDispatcher(Duck.class, mDuckReceiver),
ChannelHelper.newDispatcher(Chicken.class, mChickenReceiver)
);
// 创建一个 HandlerPipe 对象
HandlerPipe handlerPipe = new HandlerPipe(mergeDispatcher);
// 创建 emitter：共享同一个 HandlerPipe 对象
Duck duckEmitter = ChannelHelper.newEmitter(Duck.class, handlerPipe);
Chicken chickenEmitter = ChannelHelper.newEmitter(Chicken.class, handlerPipe);MIT License
Copyright (c) 2020 jrfeng
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SOFTWARE.