目录

一、线程名称设置和获取

二、线程的sleep()

三、线程的interrupt

四、join()

五、yield()

六、wait(),notify(),notifyAll()

一、线程名称设置和获取

1、线程名称一般在线程启动前设置&＃xff0c;但也允许为正在运行的线程设置名称。在实际开发中&＃xff0c;在使用多线程开发时&＃xff0c;一定要自定义线程名称&＃xff0c;偏于查找日志。

2、线程允许使用同样的名字&＃xff0c;但应该尽量避免。

3、如果线程没有命名&＃xff0c;系统会自动为线程设置名称。例如Thread-0,Thread-1。在SpringBoot中http-nio-端口号-exec-1&＃xff0c;http-nio-端口号-exec-2。

线程命名

package com.xiaojie.juc.thread.base;/*** &＃64;author xiaojie* &＃64;version 1.0* &＃64;description: 线程命名和获取名称* &＃64;date 2021/12/17 22:54*/
public class ThreadNameDemo {public static void main(String[] args) {A a &＃61; new A();new Thread(a,"mythraed-a").start();new Thread(a,"mythraed-b").start();}static class A implements Runnable{&＃64;Overridepublic void run() {//获取线程名称System.out.println("当前线程的名称是>>>>>>>>:"&＃43;Thread.currentThread().getName());}}
}


线程池命名

package com.xiaojie.juc.thread.base;import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;/*** &＃64;author xiaojie* &＃64;version 1.0* &＃64;description: 线程池命名* &＃64;date 2021/12/17 23:09*/
public class ThreadPoolNameDemo {private static final AtomicInteger threadNumber &＃61; new AtomicInteger(1);private static final String MYTHREAD_POOL_GROUP &＃61; "mythread-pool-group-thread-";public static void main(String[] args) {ExecutorService executorService &＃61; Executors.newFixedThreadPool(3, r -> new Thread(new ThreadGroup(""), r,MYTHREAD_POOL_GROUP &＃43; threadNumber.getAndIncrement(),0));for (int i &＃61; 0; i <10; i&＃43;&＃43;) {executorService.execute(() -> System.out.println("当前线程名称>>>>>>>>>:" &＃43; Thread.currentThread().getName()));}//关闭线程池executorService.shutdown();}
}


二、线程的sleep()

package com.xiaojie.juc.thread.base;import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;/*** &＃64;author xiaojie* &＃64;version 1.0* &＃64;description: 线程sleep方法* &＃64;date 2021/12/17 23:46*/
public class ThreadSleepDemo {public static void main(String[] args) {ExecutorService executorService &＃61; Executors.newFixedThreadPool(3);for (int i &＃61; 0; i <10; i&＃43;&＃43;) {executorService.execute(() -> {try {if (Thread.currentThread().isInterrupted()) {System.out.println("Thread is Interrupted");}//一定要捕捉InterruptedException异常Thread.sleep(1000);} catch (InterruptedException e) {}System.out.println(Thread.currentThread().getName());});}//关闭线程池executorService.shutdown();}
}


sleep的作用是让目前正在执行的线程休眠&＃xff0c;让CPU去执行其他任务&＃xff0c;使线程从运行状态进去阻塞状态。当线程睡眠时间满后&＃xff0c;线程并不一定是立刻马上开始执行&＃xff0c;因为CPU可能正在执行其他任务&＃xff0c;线程进入就绪状态&＃xff0c;等待CPU分配时间片后才能执行。

三、线程的interrupt

Thread提供了stop()&＃xff0c;但是是个过时方法&＃xff0c;不推荐使用。stop()方法是强制中断线程&＃xff0c;不管当前线程是否正在运行&＃xff0c;有可能导致当前线程持有当前锁&＃xff0c;强行中断后可能不会释放锁。interrupt()并不是用来中断一个线程&＃xff0c;而是将线程设置为中断状态。

1、如果执行interrupt()时&＃xff0c;当前线程处于阻塞状态&＃xff08;wait(),sleep(),join()&＃xff09;时&＃xff0c;线程会立刻退出阻塞&＃xff0c;抛出InterruptedException异常。

2、如果调用interrupt()时&＃xff0c;线程处于运行状态&＃xff0c;线程不受任何影响&＃xff0c;只是会将中断标识设置为true,可以调用isInterrupted(),判断是否中断。

package com.xiaojie.juc.thread.base;/*** &＃64;author xiaojie* &＃64;version 1.0* &＃64;description: 线程中断* &＃64;date 2021/12/18 0:12*/
public class InterruptDemo {public static void main(String[] args) {A a &＃61; new A();a.start();}static class A extends Thread {&＃64;Overridepublic void run() {//手动中断线程Thread.currentThread().interrupt();try {while (true) {if (Thread.currentThread().isInterrupted()) {System.out.println("线程中断了");break;}}Thread.sleep(3000);System.out.println(Thread.currentThread().getName());} catch (InterruptedException e) {e.printStackTrace();System.out.println("线程中断了。。。。。when sleep");}}}
}


四、join()

 线程A在运行时&＃xff0c;线程Bjoin(),之后&＃xff0c;线程A会等待直到线程B运行完之后&＃xff0c;才开始执行。如果线程B无限制运行&＃xff0c;线程A可以设置等待时长join(1000)单位是毫秒。

package com.xiaojie.juc.thread.base;/*** &＃64;author xiaojie* &＃64;version 1.0* &＃64;description:线程join模拟* &＃64;date 2021/12/18 0:45*/
public class ThreadJoinDemo {public static void main(String[] args) {new A().start();}static class A extends Thread {&＃64;Overridepublic void run() {try {B b &＃61; new B();b.start();b.join();//B线程join之后&＃xff0c;A线程需要等待B运行完之后才执行} catch (InterruptedException e) {e.printStackTrace();}System.out.println("线程A执行任务。。。。。。。");}}static class B extends Thread {&＃64;Overridepublic void run() {try {Thread.sleep(3000);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("线程B执行任务。。。。。。。");}}
}


五、yield()

yield的作用是让正在执行的线程让出CPU的执行权限&＃xff0c;使得CPU可以去执行其他任务。从线程状态来看&＃xff0c;线程从运行变为就绪状态。线程在yield()方法之后&＃xff0c;线程放弃和重占CPU是不确定的&＃xff0c;可能是刚刚放弃CPU&＃xff0c;马上又获得CPU执行权。yield不会阻塞线程&＃xff0c;只会让当前线程暂停一下&＃xff0c;让系统线程调度器重新调度一次。

package com.xiaojie.juc.thread.base;/*** &＃64;author xiaojie* &＃64;version 1.0* &＃64;description: Yield实例* &＃64;date 2021/12/18 1:13*/
public class ThreadYieldDemo {public static void main(String[] args) {Thread threadA &＃61; new Thread(new A());threadA.setPriority(1);threadA.setName("threadA ");Thread threadB &＃61; new Thread(new B());threadB.setName("threadB ");threadA.start();threadB.start();}static class A implements Runnable {&＃64;Overridepublic void run() {//暂停一下,重新调度线程Thread.yield();System.out.println(Thread.currentThread().getName());}}static class B implements Runnable {&＃64;Overridepublic void run() {System.out.println(Thread.currentThread().getName());}}
}


六、wait(),notify(),notifyAll()

这三个方法不是Thread独有的方法&＃xff0c;是Object的方法&＃xff01;&＃xff01;&＃xff01;

当一个对象实例调用了wait()方法后&＃xff0c;当前线程会在这个对象上等待。直到其他线程调用这个实例的notify(),或者notifyAll()方法后才会唤醒。调用了wait()方法后&＃xff0c;该线程就会进入该实例的等待队列&＃xff0c;如果队列中有多个线程&＃xff0c;notify()只会随机的唤醒一个线程。这个选择是不公平的&＃xff0c;不是先等待的就会先唤醒。notifyAll(),是唤醒所有的等待线程。而且这些方法只能在synchronized代码块中使用。wait&＃xff08;&＃xff09;和sleep()都会让线程等待&＃xff0c;但是wait()方法会释放目标对象的锁&＃xff0c;而sleep()方法不会释放任何资源。

package com.xiaojie.juc.thread.base;/*** &＃64;author xiaojie* &＃64;version 1.0* &＃64;description: wait demo* &＃64;date 2021/12/18 1:43*/
public class ThreadWaitDemo {private static final Object obj &＃61; new Object();public static void main(String[] args) {new Thread(new A()).start();new Thread(new B()).start();}static class A implements Runnable {&＃64;Overridepublic void run() {synchronized (obj) {System.out.println("线程A开始等待。。。。。。");try {obj.wait();} catch (InterruptedException e) {e.printStackTrace();}System.out.println("线程A等待结束。。。。。。");System.out.println("线程A开始执行。。。。。。");}}}static class B implements Runnable {&＃64;Overridepublic void run() {synchronized (obj) {try {obj.notify();Thread.sleep(2000);System.out.println("线程B运行。。。。。");} catch (InterruptedException e) {e.printStackTrace();}}}}
}


参考&＃xff1a;《JAVA高并发核心编程&＃xff08;卷2&＃xff09;&＃xff1a;多线程、锁、JMM、JUC、高并发设计》-尼恩编著