做网站卖产品投资大嘛,设计一个网站的价格表,高德地图可以搜索国外吗,手工制作飞机图形说明: Thread.State源码注释:
public enum State {/*** 新生状态#xff1a;线程对象创建#xff0c;但是还未start()*/NEW,/*** 线程处于可运行状态#xff0c;但是这个可运行状态并不代表线程一定在虚拟机中执行。* 需要等待从操作系统获取到资源(比如处理器时间片…图形说明: Thread.State源码注释:
public enum State {/*** 新生状态线程对象创建但是还未start()*/NEW,/*** 线程处于可运行状态但是这个可运行状态并不代表线程一定在虚拟机中执行。* 需要等待从操作系统获取到资源(比如处理器时间片)才能真正的去运行*/RUNNABLE,/*** 当前线程处于阻塞状态正在等待另一个线程的monitor lock释放才进入synchronized代码块或方法*/BLOCKED,/*** 调用Object#wait() 、 Thread.join方法后当前线程处于等待状态* 等待其他的线程执行特定的动作才能从等待状态退出。* 比如Object.wait()的线程需要等待其他线程调用Object.notify()、Object.notifyAll()才能退出* 比如调用了Thread.join()的线程需要等待指定的线程执行完成才能退出等待状态。*/WAITING,/*** 进入特定时间内的等待状态等待一段指定的时间sleep(timed)、wait(timed)或者等待Thread.join(timed)的时间.* 到达指定时间点自动退出恢复到RUNNABLE状态*/TIMED_WAITING,/*** 线程结束状态*/TERMINATED;
}代码示例: NEW状态:
public class ThreadState {public static void main(String[] args) throws Exception {Thread thread new Thread();System.out.println(thread.getState());}
}结果:
RUNNABLE状态:
public static void main(String[] args) throws Exception {Thread thread new Thread(()- {while (true){Thread.yield();}});thread.start();Thread.sleep(2000);System.out.println(thread.getState());}
}结果:
WAITING状态:
public static void main(String[] args) throws Exception {Thread thread new Thread(()- {LockSupport.park();while (true){Thread.yield();}});thread.start();Thread.sleep(50);System.out.println(thread.getState());LockSupport.unpark(thread);Thread.sleep(50);System.out.println(thread.getState());}结果: join方法代码: 可见Thread#join()是在线程实例存活的时候总是调用Object#wait()方法也就是必须在线程执行完毕isAlive()为false意味着线程生命周期已经终结的时候才会解除阻塞。
TIMED WAITING状态:
public static void main(String[] args) throws Exception {Thread thread new Thread(()- {try {Thread.sleep(1000);} catch (InterruptedException e) {//ignore}});thread.start();thread.notify();Thread.sleep(50);System.out.println(thread.getState());Thread.sleep(1000);System.out.println(thread.getState());}结果: BLOCKED状态: BLOCKED状态也就是阻塞状态该状态下的线程不会被分配CPU执行时间。线程的状态为BLOCKED的时候有两种可能的情况
A thread in the blocked state is waiting for a monitor lock to enter a synchronized block/method
1.线程正在等待一个监视器锁只有获取监视器锁之后才能进入synchronized代码块或者synchronized方法
在此等待获取锁的过程线程都处于阻塞状态。reenter a synchronized block/method after calling Object#wait()
2.线程X步入synchronized代码块或者synchronized方法后此时已经释放监视器锁调用Object#wait()方法之后进行阻塞
当接收其他线程T调用该锁对象Object#notify()/notifyAll()但是线程T尚未退出它所在的synchronized代码块或者synchronized方法
那么线程X依然处于阻塞状态注意API注释中的reenter理解它场景2就豁然开朗。private static final Object MONITOR new Object();private static final DateTimeFormatter F DateTimeFormatter.ofPattern(yyyy-MM-dd HH:mm:ss);public static void main(String[] args) throws Exception {System.out.printf([%s]-begin...%n, F.format(LocalDateTime.now()));Thread thread1 new Thread(() - {synchronized (MONITOR) {System.out.printf([%s]-thread1 got monitor lock...%n, F.format(LocalDateTime.now()));try {Thread.sleep(1000);MONITOR.wait();} catch (InterruptedException e) {//ignore}System.out.printf([%s]-thread1 exit waiting...%n, F.format(LocalDateTime.now()));}});Thread thread2 new Thread(() - {synchronized (MONITOR) {System.out.printf([%s]-thread2 got monitor lock...%n, F.format(LocalDateTime.now()));try {MONITOR.notify();//这个时候thread2已经释放了MONITOR锁,thread1已经被唤醒但是因为thread2还在占用MONITOR所以thread1是blocked状态//对应 reenter a synchronized block/method after calling Object#wait()Thread.sleep(2000);} catch (InterruptedException e) {//ignore}System.out.printf([%s]-thread2 releases monitor lock...%n, F.format(LocalDateTime.now()));}});thread1.start();thread2.start();// 这里故意让主线程sleep 1500毫秒从而让thread2调用了Object#notify()并且尚未退出同步代码块确保thread1调用了Object#wait()Thread.sleep(1500); System.out.println(thread1.getState());System.out.printf([%s]-end...%n, F.format(LocalDateTime.now()));}结果: 源码的注释说的就是上述测试的情况,虽然调用了notify方法但是被唤醒的线程并不会进入RUNNABLE状态需要等thread2释放锁以后重新参与锁竞争
TERMINATED状态
public static void main(String[] args) throws Exception {Thread thread new Thread(() - {});thread.start();Thread.sleep(50);System.out.println(thread.getState());}结果:
