Thread 类的基本用法

目录

一、Thread类

二、线程创建

三、线程中断

四、线程等待

五、线程休眠

六、获取线程实例

在java标准库中,提供了一个Thread类,用来表示/操作线程,Thread类可以视为是Java标准库提供的API,Java是支持多线程编程的,在Java中创建好的Thread实例,其实和操作系统中的线程是一一对应的关系,操作系统提供了一组关于线程的API(C语言),Java对于这组API进一步封装之后就变成了Thread类

二、线程创建

1. 继承 Thread, 重写 run

       public static void main(String[] args) {
           //继承的写法1.自定义一个类来继承
           MyThread myThread = new 
           myThread.start();
   
           //继承的写法2.使用一个匿名内部类
           Thread t = new Thread(){//属于继承Thread但没有名称的子类
              @Override
               public void run() {
                  System.out.println("匿名内部类 run");
              }
           };
           t.start();
       }
       //继承的方式：1.继承Thread，2.重写run方法（定义要执行的任务代码）
       private static class MyThread extends Thread{
           @Override
           public void run() {
               System.out.println("mythread run");
               }
       }
   }

2. 实现 Runnable, 重写 run，使用 lambda 表达式

   public class 实现Runnable {
   
       public static void main(String[] args) {
           //写法1
           Thread t1 = new Thread(new MyRunnable());
           t1.start();
   
           //写法2：匿名内部类
           Runnable r2 = new Runnable() {
               @Override
               public void run() {
                   System.out.println("匿名内部类run");
               }
           };
           Thread t2 = new Thread(r2);
           t2.start();
   
           //写法3：把匿名内部类对象，直接写在构造方法的参数上
           Thread t3 = new Thread(new Runnable() {
               @Override
               public void run() {
                   System.out.println("匿名内部类run");
               }
           });
           t3.start();
   
           //写法4：lambda表达式
           Thread t4 = new Thread(() -> System.out.println("匿名内部类run"));
           t4.start();
       }
   
       private static class MyRunnable implements Runnable{
           @Override
           public void run() {
               System.out.println("MyRunnable run");
           }
       }
   }

三、线程中断

1. 设置标志位

   public class 自定义标志位 {
   
       //先设计一个标志位：表示是否被中断。
       private static volatile boolean 是否被中断 = false;
   
       public static void main(String[] args) throws InterruptedException {
           Thread t = new Thread(new Runnable() {
               @Override
               public void run() {
                   //循环10次，每次打印次数，并休眠1秒
                   try {
                       //判断条件加上标志位
                       for (int i = 0; i < 10 && !是否被中断; i++) {
                           System.out.println(i);
                           //自定义标志位，能够实现某些条件的中断
                           //但如果线程处于等待/超时等待/阻塞, 就没法中断
                           //修改时间为100秒就没法中断
                           Thread.sleep(1000);
                       }
                   } catch (InterruptedException e) {
                       e.printStackTrace();
                   }
               }
           });
           t.start();
           //要中断t线程：等3后再中断
           Thread.sleep(3000);
           是否被中断 = true;
       }
   }

2. Thread类内部包含了一个boolean的变量可以用来作为标记位,标记是否被中断Thread.interrupted()或者Thread.currentThread().isInterrupted()都可以

   public class demo {
   
       public static void main(String[] args) {
           Thread t = new Thread() {
               @Override
               public void run() {
                   while (!Thread.currentThread().isInterrupted()) {
                       System.out.println("thread");
                       try {
                           Thread.sleep(1000);
                       } catch (InterruptedException e) {
                           e.printStackTrace();
                           break;
                       }
                   }
               }
           };
           t.start();
           try {
               Thread.sleep(10000);
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
           t.interrupt();
       }
   }

3. Thread.interrupted()线程中断会清除标记位,Thread.currentThread().isInterrupted()线程标记位不会被清空

   public class IsInterrupted {
   
       public static void main(String[] args) {
           Thread thread1 = new Thread(){
               @Override
               public void run() {
                   for (int i = 0; i < 5; i++) {
                       System.out.println(Thread.interrupted());
                   }
               }
           };
           thread1.start();
           thread1.interrupt();
           Thread thread2 = new Thread(){
               @Override
               public void run() {
                   for (int i = 0; i < 5; i++) {
                       System.out.println(Thread.currentThread().isInterrupted());
                   }
               }
           };
           thread2.start();
           thread2.interrupt();
       }
   }

四、线程等待

使用join方法

public class 线路等待 {

    public static void main(String[] args) {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < 3; i++) {
                    System.out.println("thread");
                    try {
                        Thread.sleep(1000);
                        } catch(InterruptedException e){
                            e.printStackTrace();
                        }
                    }
            }
        });
        t.start();
        try {
            t.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("bit");
    }
}

五、线程休眠

使用sleep方法

public class 线程休眠 {

    public static void main(String[] args){
        Thread t = new Thread() {
            @Override
            public void run() {
                while (true) {
                    System.out.println("thread");
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        t.start();
    }
}

六、获取线程实例

package thread;
public class 获取线程实例 {
    public static void main(String[] args) {
        Thread t = Thread.currentThread();
        System.out.println(t.getName() + ":id:" + t.getId());
        System.out.println(t.getName() + ":名称:" + t.getName());
        System.out.println(t.getName() + ":状态:" + t.getState());
        System.out.println(t.getName() + ":优先级:" + t.getPriority());
        System.out.println(t.getName() + ":是不是后台线程:" + t.isDaemon());
        System.out.println(t.getName() + ":是否存活:" + t.isAlive());
        System.out.println(t.getName() + ":是否被中断:" + t.isInterrupted());
 
    }
}