15：EventBus源码解析-白红宇

1、ThreadLocal

Thread类中有一个threadLocals字段，它是ThreadLocal内部类ThreadLocalMap类型。

ThreadLocal的set方法：操作当前线程的threadLocals，以ThreadLocal.this为键，将值保存到Thread.threadLocals中

ThreadLocal的get方法：取出当前线程的threadLocals中以ThreadLocal.this为键的值

//ThreadLocal.java    public void set(T value) {        Thread t = Thread.currentThread();        ThreadLocalMap map = getMap(t);        if (map != null)            map.set(this, value);        else            createMap(t, value);    }    ThreadLocalMap getMap(Thread t) {        return t.threadLocals;    }        void createMap(Thread t, T firstValue) {        t.threadLocals = new ThreadLocalMap(this, firstValue);    }        public T get() {        Thread t = Thread.currentThread();        ThreadLocalMap map = getMap(t);        if (map != null) {            ThreadLocalMap.Entry e = map.getEntry(this);            if (e != null) {                @SuppressWarnings("unchecked")                T result = (T)e.value;                return result;            }        }        return setInitialValue();    }    复制代码

ThreadLocal构造函数，可指定保存的数据类型，以及重写initialValue设置初始值。之后就可以在不同线程中使用threadLocal的set、get方法，保存此数据类型的数据了。

//EventBus.java    private final ThreadLocal
    
      currentPostingThreadState = new ThreadLocal
     
      () {        @Override        protected PostingThreadState initialValue() {            return new PostingThreadState();        }    };复制代码

1、ThreadLocal

2、架构

3、源码