定义事件类型

public class FBBaseEvent {
    public static final int START = 0x0;
    public static final int LOADING = 0x10;
    public static final int SUCCESS = 0x20;
    public static final int FAIL = 0x30;
    
    public int type;

    public FBBaseEvent(int type) {
        this.type = type;
    }
}

public class FBEvent {
    public static class Login extends FBBaseEvent {
        public Login(int type) {
            super(type);
        }
    }
}

使用步骤说明

/**
 * Registers the given subscriber to receive events. Subscribers must call {@link #unregister(Object)} once they
 * are no longer interested in receiving events.
 *
 * Posts the given event to the event bus. 
 *
 * Subscribers have event handling methods that are identified by their name, typically called "onEvent". Event
 * handling methods must have exactly one parameter, the event. If the event handling method is to be called in a
 * specific thread, a modifier is appended to the method name. Valid modifiers match one of the {@link ThreadMode}
 * enums. For example, if a method is to be called in the UI/main thread by EventBus, it would be called
 * "onEventMainThread".
 */

注册（一般使用在Activity和Fragment）

EventBus.getDefault().register(this);

销毁（一般使用在Activity和Fragment）

EventBus.getDefault().unregister(this);

发送事件（一般使用在Presenter）

EventBus.getDefault().post(new FBEvent.Login(FBEvent.Login.LOADING));
EventBus.getDefault().post(new FBEvent.Login(FBEvent.Login.SUCCESS));

处理操作（一般使用在Activity和Fragment）

public void onEventMainThread(FBEvent.Login event) {
    switch (event.type) {
        case FBEvent.Login.START:
            //处理操作
            break;
        case FBEvent.Login.SUCCESS:
            //处理操作
            break;
        case FBEvent.Login.FAIL:
            //处理操作
            break;
    }
}

总结：EventBus比较常用于MVP设计模式中。

参考资料：(建议按顺序查看)
1.官方
2.Android解耦库EventBus的使用和源码分析