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简介
EventBus#xff1a;github
EventBus是Android和Java的发布/订阅事件总线。
简化组件之间的通信 解耦事件发送者和接收者 在 Activities, Fragments, background threads中表现良好 避免复杂且容易出错的依赖关系和生命周期问题
Publisher使用post发出…EventBus
简介
EventBusgithub
EventBus是Android和Java的发布/订阅事件总线。
简化组件之间的通信 解耦事件发送者和接收者 在 Activities, Fragments, background threads中表现良好 避免复杂且容易出错的依赖关系和生命周期问题
Publisher使用post发出一个Event事件Subscriber在onEvent()函数中接收事件。 EventBus 是一款在 Android 开发中使用的发布/订阅事件总线框架基于观察者模式将事件的接收者和发送者分开简化了组件之间的通信使用简单、效率高、体积小下边是官方的 EventBus 原理图 导入
Android Projects
implementation(org.greenrobot:eventbus:3.2.0)Java Projects:
implementation(org.greenrobot:eventbus-java:3.2.0)dependencygroupIdorg.greenrobot/groupIdartifactIdeventbus-java/artifactIdversion3.2.0/version
/dependency配置
配置混淆文件
-keepattributes *Annotation*
-keepclassmembers class * {org.greenrobot.eventbus.Subscribe methods;
}
-keep enum org.greenrobot.eventbus.ThreadMode { *; }# If using AsyncExecutord, keep required constructor of default event used.
# Adjust the class name if a custom failure event type is used.
-keepclassmembers class org.greenrobot.eventbus.util.ThrowableFailureEvent {init(java.lang.Throwable);
}# Accessed via reflection, avoid renaming or removal
-keep class org.greenrobot.eventbus.android.AndroidComponentsImpl使用
简单流程
创建事件类
public static class MessageEvent { /* Additional fields if needed */ }在需要订阅事件的地方声明订阅方法并注册EventBus。
Subscribe(threadMode ThreadMode.MAIN)
public void onMessageEvent(MessageEvent event) {// Do something
}public class EventBusActivity extends AppCompatActivity {Overrideprotected void onCreate(Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);}Overrideprotected void onStart() {super.onStart();//注册EventBusEventBus.getDefault().register(this);}//接收事件Subscribe(threadMode ThreadMode.POSTING, sticky true, priority 1)public void onReceiveMsg(MessageEvent message){Log.e(EventBus_Subscriber, onReceiveMsg_POSTING: message.toString());}//接收事件Subscribe(threadMode ThreadMode.MAIN, sticky true, priority 1)public void onReceiveMsg1(MessageEvent message){Log.e(EventBus_Subscriber, onReceiveMsg_MAIN: message.toString());}//接收事件Subscribe(threadMode ThreadMode.MAIN_ORDERED, sticky true, priority 1)public void onReceiveMsg2(MessageEvent message){Log.e(EventBus_Subscriber, onReceiveMsg_MAIN_ORDERED: message.toString());}Overrideprotected void onDestroy() {super.onDestroy();//取消事件EventBus.getDefault().unregister(this);}
}提交订阅事件
OnClick(R2.id.send_event_common)
public void clickCommon(){MessageEvent message new MessageEvent(1, 这是一条普通事件);EventBus.getDefault().post(message);
}OnClick(R2.id.send_event_sticky)
public void clickSticky(){MessageEvent message new MessageEvent(1, 这是一条黏性事件);EventBus.getDefault().postSticky(message);
}Subcribe注解
Subscribe是EventBus自定义的注解共有三个参数可选threadMode、boolean sticky、int priority。 完整的写法如下
Subscribe(threadMode ThreadMode.MAIN,sticky true,priority 1)
public void onReceiveMsg(MessageEvent message) {Log.e(TAG, onReceiveMsg: message.toString());
}priority
priority是优先级是一个int类型默认值为0。值越大优先级越高越优先接收到事件。
值得注意的是只有在post事件和事件接收处理处于同一个线程环境的时候才有意义。
sticky
sticky是一个boolean类型默认值为false默认不开启黏性sticky特性那么什么是sticky特性呢
上面的例子都是对订阅者 (接收事件) 先进行注册然后在进行post事件。
那么sticky的作用就是订阅者可以先不进行注册如果post事件已经发出再注册订阅者同样可以接收到事件并进行处理。
ThreadMode 模式
POSITING订阅者将在发布事件的同一线程中被直接调用。这是默认值。事件交付意味着最少的开销因为它完全避免了线程切换。因此对于已知可以在很短时间内完成而不需要主线程的简单任务推荐使用这种模式。使用此模式的事件处理程序必须快速返回以避免阻塞发布线程(可能是主线程)。
MAIN在Android上订阅者将在Android的主线程(UI线程)中被调用。如果发布线程是主线程将直接调用订阅者方法阻塞发布线程。否则事件将排队等待交付(非阻塞)。使用此模式的订阅者必须快速返回以避免阻塞主线程。如果不是在Android上行为与POSITING相同。
MAIN_ORDERED在Android上订阅者将在Android的主线程(UI线程)中被调用。与MAIN不同的是事件将始终排队等待交付。这确保了post调用是非阻塞的。
BACKGROUND在Android上订阅者将在后台线程中被调用。如果发布线程不是主线程订阅者方法将在发布线程中直接调用。如果发布线程是主线程EventBus使用一个后台线程它将按顺序传递所有事件。使用此模式的订阅者应尽量快速返回以避免阻塞后台线程。如果不是在Android上总是使用一个后台线程。
ASYNC订阅服务器将在单独的线程中调用。这始终独立于发布线程和主线程。使用此模式发布事件从不等待订阅者方法。如果订阅者方法的执行可能需要一些时间例如网络访问则应该使用此模式。避免同时触发大量长时间运行的异步订阅者方法以限制并发线程的数量。EventBus使用线程池来有效地重用已完成的异步订阅者通知中的线程。
/*** Each subscriber method has a thread mode, which determines in which thread the method is to be called by EventBus.* EventBus takes care of threading independently from the posting thread.* * see EventBus#register(Object)* author Markus*/
public enum ThreadMode {/*** Subscriber will be called directly in the same thread, which is posting the event. This is the default. Event delivery* implies the least overhead because it avoids thread switching completely. Thus this is the recommended mode for* simple tasks that are known to complete in a very short time without requiring the main thread. Event handlers* using this mode must return quickly to avoid blocking the posting thread, which may be the main thread.*/POSTING,/*** On Android, subscriber will be called in Androids main thread (UI thread). If the posting thread is* the main thread, subscriber methods will be called directly, blocking the posting thread. Otherwise the event* is queued for delivery (non-blocking). Subscribers using this mode must return quickly to avoid blocking the main thread.* If not on Android, behaves the same as {link #POSTING}.*/MAIN,/*** On Android, subscriber will be called in Androids main thread (UI thread). Different from {link #MAIN},* the event will always be queued for delivery. This ensures that the post call is non-blocking.*/MAIN_ORDERED,/*** On Android, subscriber will be called in a background thread. If posting thread is not the main thread, subscriber methods* will be called directly in the posting thread. If the posting thread is the main thread, EventBus uses a single* background thread, that will deliver all its events sequentially. Subscribers using this mode should try to* return quickly to avoid blocking the background thread. If not on Android, always uses a background thread.*/BACKGROUND,/*** Subscriber will be called in a separate thread. This is always independent from the posting thread and the* main thread. Posting events never wait for subscriber methods using this mode. Subscriber methods should* use this mode if their execution might take some time, e.g. for network access. Avoid triggering a large number* of long running asynchronous subscriber methods at the same time to limit the number of concurrent threads. EventBus* uses a thread pool to efficiently reuse threads from completed asynchronous subscriber notifications.*/ASYNC
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