线程状态

    public enum State {
        /**
         * Thread state for a thread which has not yet started.
         */
        NEW,

        /**
         * Thread state for a runnable thread.  A thread in the runnable
         * state is executing in the Java virtual machine but it may
         * be waiting for other resources from the operating system
         * such as processor.
         */
        RUNNABLE,

        /**
         * Thread state for a thread blocked waiting for a monitor lock.
         * A thread in the blocked state is waiting for a monitor lock
         * to enter a synchronized block/method or
         * reenter a synchronized block/method after calling
         * {@link Object#wait() Object.wait}.
         */
        BLOCKED,

        /**
         * Thread state for a waiting thread.
         * A thread is in the waiting state due to calling one of the
         * following methods:
         * <ul>
         *   <li>{@link Object#wait() Object.wait} with no timeout</li>
         *   <li>{@link #join() Thread.join} with no timeout</li>
         *   <li>{@link LockSupport#park() LockSupport.park}</li>
         * </ul>
         *
         * <p>A thread in the waiting state is waiting for another thread to
         * perform a particular action.
         *
         * For example, a thread that has called {@code Object.wait()}
         * on an object is waiting for another thread to call
         * {@code Object.notify()} or {@code Object.notifyAll()} on
         * that object. A thread that has called {@code Thread.join()}
         * is waiting for a specified thread to terminate.
         */
        WAITING,

        /**
         * Thread state for a waiting thread with a specified waiting time.
         * A thread is in the timed waiting state due to calling one of
         * the following methods with a specified positive waiting time:
         * <ul>
         *   <li>{@link #sleep Thread.sleep}</li>
         *   <li>{@link Object#wait(long) Object.wait} with timeout</li>
         *   <li>{@link #join(long) Thread.join} with timeout</li>
         *   <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
         *   <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
         * </ul>
         */
        TIMED_WAITING,

        /**
         * Thread state for a terminated thread.
         * The thread has completed execution.
         */
        TERMINATED;
    }

1）当我们new了thread实例后，线程就进入了NEW状态；

2）当该对象调用了start()方法，就进入RUNNABLE状态；

3）进入可运行状态后，当该对象被操作系统选中，获得CPU时间片就会进入运行状态；

4）进入运行状态后case就比较多，大致有如下情形：
run()方法或main()方法结束后，线程就进入TERMINATED状态； 当线程调用了自身的sleep()方法或其他线程的join()方法，就会进入阻塞状态(该状态既停 止当前线程，但并不释放所占有的资源)。

当sleep()结束或join()结束后，该线程进入可运行状态，继续等待OS分配时间片； 当线程刚进入可运行状态(注意，还没运行)，发现将要调用的资源被锁牢(synchroniza,lock)，将会立即进入锁池状态，等待获取锁标记(这时的锁池里也许已经有了其他线程在等待获取锁标记，这时它们处于队列状态，既先到先得)，一旦线程获得锁标记后，就转入可运行状态，等待OS分配 CPU时间片； 当线程调用wait()方法后会进入等待队列(进入这个状态会释放所占有的所有资源，与阻塞状态不同)，进入这个状态后，是不能自动唤醒的，必须依靠其他线程调用notify()或notifyAll()方法才能被唤醒(由于notify()只是唤醒一个线程，但我们由不能确定具体唤醒的是哪一个线程，也许我们需要唤醒的线程不能够被唤醒，因此在实际使用时，一般都用notifyAll()方法，唤醒所有线程)，线程被唤醒后会进入锁池，等待获取锁标记。
当线程调用stop方法，即可使线程进入消亡状态，但是由于stop方法是不安全的，不鼓励使用，可以通过run方法里的条件变通实现线程的 stop。

1. 通过中断进行线程通讯

在BLOCKED, WAITING, TIMED_WAITING中，终端标记为true会立即抛出异常。在运行过程则需要手动处理。

public boolean isInterrupted()
public static boolean interrupted() // 会清楚终端标记

void test(){
    while(Thread.interrupted()){throw new InterruptedException();}
}

2. 阻塞队列实现生产者消费者模型##

LinkedBlockingQueue
take，put一直等待;poll，offer可以设置等待时间，也可以不等待则不抛出InterruptedException
支持同时存取，因为有两个锁，takeLock和putLock

    /** Lock held by take, poll, etc */
    private final ReentrantLock takeLock = new ReentrantLock();
    /** Wait queue for waiting takes */
    private final Condition notEmpty = takeLock.newCondition();
    /** Lock held by put, offer, etc */
    private final ReentrantLock putLock = new ReentrantLock();
    /** Wait queue for waiting puts */
    private final Condition notFull = putLock.newCondition();

ArrayBlockingQueue 支持公平队列，生产者消费者有序排队
使用公平锁

    public ArrayBlockingQueue(int capacity, boolean fair) {
        if (capacity <= 0)
            throw new IllegalArgumentException();
        this.items = new Object[capacity];
        lock = new ReentrantLock(fair);
        notEmpty = lock.newCondition();
        notFull =  lock.newCondition();
    }