博客

/**
 * 手写需要在方法上添加该参数，让该方法执行的时候，在哪个线程接收通知
 */
public enum ThreadMode {

    /**
     * 当前线程接收
     */
    PostThread,
    /**
     * 主线程接收
     */
    MainThread,
    /**
     * 异步线程接收
     */
    BackgroundThread,
    /**
     * 独立线程接收
     */
    Async,

}

/**
 *订阅的事件和方法.
 * 1：处理事件线程。ThreadMode
 * 2：处理事件订阅方法类
 * 3：Method 处理事件方法名称
 *
 * 该类存储的是  一个方法 对应注解上的参数 和类名称
 */
public class SubscribleMethod {

    private final Method method;
    private final ThreadMode threadMode;
    private final Class<?> aClassType;

    public SubscribleMethod(Method method, ThreadMode threadMode, Class<?> aClassType) {
        this.method = method;
        this.threadMode = threadMode;
        this.aClassType = aClassType;
    }

    public Method getMethod() {
        return method;
    }

    public ThreadMode getThreadMode() {
        return threadMode;
    }

    public Class<?> getaClassType() {
        return aClassType;
    }

}

@Retention(RetentionPolicy.RUNTIME)
public @interface Subscribe {

    ThreadMode threadMode() default ThreadMode.PostThread;

}

package com.ml.demo06.eventbus;

import android.os.Handler;
import android.os.Looper;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class EventBus {

    private final Handler handler;
    private final ExecutorService executorService;
    private final HashMap<Object, List<SubscribleMethod>> cacheMap;

    public static class EventBusHolder {
        private static EventBus instance = new EventBus();
    }

    private EventBus() {
        //主线程中的handler
        handler = new Handler(Looper.getMainLooper());
        executorService = Executors.newCachedThreadPool();
        cacheMap = new HashMap<>();
    }

    /**
     * eventbus的注册
     */
    public void register(Object activity) {
        //根据activity对象获取该对象所有事件列表
        List<SubscribleMethod> list = cacheMap.get(activity);
        if (list == null) {
            //创建list关于activity 的事件
            list = getSubscribleMethods(activity);
            cacheMap.put(activity, list);
        }
    }

    /**
     * 发送事件
     *
     * @param friend
     */
    public void post(final Object friend) {
        //遍历查找到的subscribe 方法 ,获取map中的所有key
        Set<Object> set = cacheMap.keySet();
        Iterator iterator = set.iterator();
        while (iterator.hasNext()) {
            final Object value = iterator.next();
            List<SubscribleMethod> list = cacheMap.get(value);

            //获取一个activity中对应的所有注解方法
            for (final SubscribleMethod subscribleMethod : list) {
                ThreadMode threadMode = subscribleMethod.getThreadMode();
                switch (threadMode) {
                    case MainThread: //主线程调用
                        if (Looper.myLooper() == Looper.getMainLooper()) {
                            invoke(subscribleMethod, value, friend);
                        } else {
                            handler.post(new Runnable() {
                                @Override
                                public void run() {
                                    invoke(subscribleMethod, value, friend);
                                }
                            });
                        }
                        break;
                    case Async: //异步线程
                        if (Looper.myLooper() == Looper.getMainLooper()) {
                            //执行在主线程，切换线程
                            executorService.execute(new Runnable() {
                                @Override
                                public void run() {
                                    invoke(subscribleMethod, value, friend);
                                }
                            });
                        } else {
                            //执行在子线程
                            invoke(subscribleMethod, value, friend);
                        }

                        break;

                    default:
                        break;
                }
            }
        }
    }

    //执行注解方法
    private void invoke(SubscribleMethod subscribleMethod, Object value, Object friend) {
        Method method = subscribleMethod.getMethod();
        try {
            method.invoke(value, friend);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }


    /**
     * 反射得到Subscrible处理事件的方法
     * 将activty所有方法上有注解的方法收集起来，包括方法名对应的注解参数
     *
     * @param activity
     * @return
     */
    private List<SubscribleMethod> getSubscribleMethods(Object activity) {
        List<SubscribleMethod> list = new ArrayList<>();
        Class<?> classType = activity.getClass();
        while (classType != null) {
            String className = classType.getName();
            if (className.startsWith("java.") || className.startsWith("javax.")
                    || className.startsWith("android.")) {
                break;
            }
            //符合要求 类或接口声明的所有方法
            Method[] methods = classType.getDeclaredMethods();
            for (Method method : methods) {
                //获取方法上有 @Subscribe 注解的方法
                Subscribe subscribe = method.getAnnotation(Subscribe.class);
                if (subscribe == null) {
                    continue;
                }

                //监测这个方法符不符合  获取方法的参数
                Class<?>[] paramtypes = method.getParameterTypes();
                if (paramtypes.length != 1) {
                    throw new RuntimeException("只能有一个参数");
                }

                //获取注解上的参数
                ThreadMode threadMode = subscribe.threadMode();
                SubscribleMethod subscribleMethod = new SubscribleMethod(method, threadMode, paramtypes[0]);
                list.add(subscribleMethod);
            }
            classType = classType.getSuperclass();

        }
        return list;
    }

    /**
     * EventBus注销
     *
     * @param activity
     */
    public void unregister(Object activity) {
        List<SubscribleMethod> list = cacheMap.get(activity);
        if (list != null) {
            cacheMap.remove(activity);
        }
    }

}