Thread is in the Blocked state while waiting for the monitor lock to enter a synchronized block or method or to reenter a synchronized block or method after calling Object.wait().
这个地方是说synchronized会导致线程进入Blocked状态，Object.wait()导致线程进入Waiting状态，Waiting线程被其他线程调用Object.notify()唤醒之后，重新获取对象上的锁的时候也会进入Blocked状态
* The current thread must own this object's monitor. The thread
* releases ownership of this monitor and waits until another thread
* notifies threads waiting on this object's monitor to wake up
* either through a call to the {@codenotify} method or the
* {@codenotifyAll} method. The thread then waits until it can
* re-obtain ownership of the monitor and resumes execution.
这是Object.wait()方法的注释，最后一句指明被唤醒的线程需要重新获取到对象的锁才能恢复执行
* The awakened thread will not be able to proceed until the current
* thread relinquishes the lock on this object. The awakened thread will
* compete in the usual manner with any other threads that might be
* actively competing to synchronize on this object; for example, the
* awakened thread enjoys no reliable privilege or disadvantage in being
* the next thread to lock this object.
这是Object.notify()方法的注释，第一句也说被唤醒的线程需要获取对象的锁
也就是说只有synchronized会导致线程进入Blocked状态，Waiting状态只能进入Blocked状态，获取锁之后才能恢复执行。
