目录

线程生命周期

Thread类的常用方法

构造方法

静态方法

常用实例方法

线程生命周期

        线程有其创建、就绪、运行、阻塞、死亡的过程，将其称之为“线程的生命周期”。如下图所示，

        对应以上5个状态，jdk-Thread类的源码中定义了枚举类State，用于描述这几个状态，

public enum State {/*** Thread state for a thread which has not yet started.新生状态：对应new Thread()的操作，但还并未调用start()方法来启动子线程。 */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.可运行状态：指的是线程创建好之后，在等待系统资源的状态。*/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}.阻塞状态：指的是线程等待重新获取同步锁（monitor lock），尝试进入/再次进入synchronized同步方法/同步代码块时的状态。*/BLOCKED,/*** Thread state for a waiting thread.* A thread is in the waiting state due to calling one of the* following methods:* 
*   
{@link Object#wait() Object.wait} with no timeout
*   
{@link #join() Thread.join} with no timeout
*   
{@link LockSupport#park() LockSupport.park}
* 
** 
A thread in the waiting state is waiting for another thread to* perform a particular action.** For example, a thread that has called Object.wait()* on an object is waiting for another thread to call* Object.notify() or Object.notifyAll() on* that object. A thread that has called Thread.join()* is waiting for a specified thread to terminate.（无限）等待状态：进入等待状态。调用Object.wait、Thread.join()、LockSupport.park方法，会导致其进入等待状态。*/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:* 
*   
{@link #sleep Thread.sleep}
*   
{@link Object#wait(long) Object.wait} with timeout
*   
{@link #join(long) Thread.join} with timeout
*   
{@link LockSupport#parkNanos LockSupport.parkNanos}
*   
{@link LockSupport#parkUntil LockSupport.parkUntil}
* 
（有限）等待状态：等待指定的时长。调用Thread.sleep、Object.wait、Thread.join、LockSupport.parkNanos、LockSupport.parkUntil会进入此状态。*/TIMED_WAITING,/*** Thread state for a terminated thread.* The thread has completed execution.死亡状态：线程体run()方法已经被执行完毕。*/TERMINATED;
}

Thread类的常用方法

        Thread类的常用方法如下，

构造方法

  其中：name为线程名称；target为包含线程体的目标对象（Runnable接口对象）。

• Thread()

• Thread(String name)

• Thread(Runnable target)

• Thread(Runnable target, String name)

静态方法

• currentThread()：返回当前正在执行的线程；

• interrupted()：返回当前执行的线程是否已经被中断；

• sleep(long millis)：使当前执行的线程睡眠多少毫秒数；

• yield()：调用此方法的线程T，将让出T所占用的同步锁资源（较少使用）。

 /*** A hint to the scheduler that the current thread is willing to yield* its current use of a processor. The scheduler is free to ignore this* hint.向调度器暗示——调用yield()方法的线程T，自愿让出CPU处理器资源，回到等待队列中，与其它线程一起参与新一轮的同步锁竞争。但是，调度器也可以忽略这个暗示。** 
 Yield is a heuristic attempt to improve relative progression* between threads that would otherwise over-utilise a CPU. Its use* should be combined with detailed profiling and benchmarking to* ensure that it actually has the desired effect.yield是一种试探性的尝试，可以避免过度使用CPU。因此，它的使用应该与详细的配置分析和基准测试相结合，以确保它实际上具有预期的效果（即：较少使用此方法）。** 
 It is rarely appropriate to use this method. It may be useful* for debugging or testing purposes, where it may help to reproduce* bugs due to race conditions. It may also be useful when designing* concurrency control constructs such as the ones in the* {@link java.util.concurrent.locks} package.较少使用yield这个方法。*/public static native void yield();

常用实例方法

• getId()：返回该线程的id；

• getName()：返回该线程的名字；

• getPriority()：返回该线程的优先级；

• interrupt()：使该线程中断；

• isInterrupted()：返回该线程是否被中断；

• isAlive()：返回该线程是否处于活动状态；

• isDaemon()：返回该线程是否是守护线程；

• setDaemon(boolean on)：将该线程标记为守护线程或用户线程，如果不标记默认是非守护线程；

• setName(String name)：设置该线程的名字；

• setPriority(int newPriority)：改变该线程的优先级；

• join()：等待该线程终止；

• join(long millis)：等待该线程终止,至多等待多少毫秒数。