Process 进程

Thread 线程

概念

程序运行起来，产生一个进程，进程执行起来则执行进程中的线程

  1. /**
  2.  * @Author: haifengzuishuai
  3.  * @Data: 2021/6/4 4:56 下午
  4.  */
  5. public class Hello extends Thread{
  6.     @Override
  7.     public void run() {
  8.         for (int i = 0; i < 20; i++) {
  9.             System.out.println("bbbb"+i);
  10.         }
  12.     }
  14.     public static void main(String[] args) {
  15.         Hello hello = new Hello();
  16.         hello.start();//调用start同时运行
  17.         for (int i = 0; i < 3; i++) {
  18.             System.out.println("aaaa"+i);
  19.         }
  21.     }
  22. }

创建多线程实例

需导入commons-io-2.6.jar包

  1. import org.apache.commons.io.FileUtils;
  3. import java.io.File;
  4. import java.io.IOException;
  5. import java.net.URL;
  7. /**
  8.  * @Author: haifengzuishuai
  9.  * @Data: 2021/6/6 8:42 下午
  10.  */
  11. public class A extends Thread {
  12.     private String url;
  13.     private String name;
  15.     public A(String url, String name) {
  16.         this.url = url;
  17.         this.name = name;
  18.     }
  20.     @Override
  21.     public void run() {
  22.         WebDownloader webDownloader = new WebDownloader();
  23.         webDownloader.downloader(url, name);
  24.         sout(name)
  25.     }
  27.     public static void main(String[] args) {
  28.         A a = new A("https://i1.hdslb.com/bfs/face/83bb511365da513c55aa3d1958524f3b7db40684.jpg@96w_96h_1c.webp", "1.jpg");
  29.         A b = new A("https://i1.hdslb.com/bfs/face/83bb511365da513c55aa3d1958524f3b7db40684.jpg@96w_96h_1c.webp", "2.jpg");
  30.         A c = new A("https://i1.hdslb.com/bfs/face/83bb511365da513c55aa3d1958524f3b7db40684.jpg@96w_96h_1c.webp", "3.jpg");
  31.         A d = new A("https://i1.hdslb.com/bfs/face/83bb511365da513c55aa3d1958524f3b7db40684.jpg@96w_96h_1c.webp", "4.jpg");
  32.         a.start();
  33.         b.start();
  34.         c.start();
  35.         d.start();
  36.     }
  37. }
  39. class WebDownloader {
  40.     public void downloader(String url, String name) {
  41.         try {
  42.             FileUtils.copyURLToFile(new URL(url), new File(name));
  43.         } catch (IOException e) {
  44.             e.printStackTrace();
  45.         }
  46.     }
  47. }

龟兔赛跑

  1. /**
  2.  * @Author: haifengzuishuai
  3.  * @Data: 2021/6/7 11:32 下午
  4.  */
  5. public class C implements Runnable {
  6.     private static String winner;
  8.     @Override
  9.     public void run() {
  10.         for (int i = 0; i <= 100; i++) {
  11.             if (Thread.currentThread().getName().equals("王八")) {
  12.                 System.out.println("休眠了");
  13.                 try {
  14.                     Thread.sleep(2);//毫秒
  15.                 } catch (InterruptedException e) {
  16.                     e.printStackTrace();
  17.                 }
  18.             }
  19.             boolean flag = gameOver(i);
  20.             if (flag) {
  21.                 break;
  22.             }
  23.             System.out.println(Thread.currentThread().getName() + "--<跑了" + i + "米");
  24.         }
  25.     }
  27.     public boolean gameOver(int steps) {
  28.         if (winner != null) {
  29.             return true;
  30.         }
  31.         {
  32.             if (steps >= 100) {
  33.                 winner = Thread.currentThread().getName();
  34.                 System.out.println("winner is " + winner);
  35.                 return true;
  36.             }
  37.         }
  38.         return false;
  39.     }
  41.     public static void main(String[] args) {
  42.         C c = new C();
  43.         new Thread(c, "兔子").start();
  44.         new Thread(c, "王八").start();
  45.     }
  46. }

lamda表达式

  1. 定义一个函数式接口
  2. 必须是函数式接口，函数式接口只有一个方法 
  1. a = (params)=>{
  2.   sout....
  3. }
  6. ILove love = null;
  7. love = a->{
  8.   sout.... 代码块
  9. }
  10. love.love(params)
  12. //函数式接口
  13. interface ILove{
  14.   void love(int a)
  15. }

线程

状态

  1. 新建Thread t = new Theread()
  2. 就绪t.start()
  3. 运行 cpu开始执行
  4. 阻塞sleep wait 或同步锁定
  5. ded 线程销毁

线程方法

线程停止flag

通过标记位的方式停止

  1. /**
  2.  * @Author: haifengzuishuai
  3.  * @Data: 2021/6/8 10:29 下午
  4.  */
  5. public class TestStop implements Runnable {
  6.     private boolean flag = true;
  8.     @Override
  9.     public void run() {
  10.         int i = 0;
  11.         while (flag) {
  12.             System.out.println("while " + i++);
  13.         }
  14.     }
  16.     public void stop() {
  17.         this.flag = false;
  18.     }
  20.     public static void main(String[] args) {
  21.         TestStop testStop = new TestStop();
  22.         new Thread(testStop).start();
  23.         for (int i = 0; i < 1000; i++) {
  24.             System.out.println("main =>" + i);
  25.             if (i == 900) {
  26.                 testStop.stop();
  27.                 System.out.println("xianchengtingzhile");
  28.             }
  29.         }
  31.     }
  32. }

线程休眠sleep

sleep

线程礼让yield

yield

线程插队join

  1. /**
  2.  * @Author: haifengzuishuai
  3.  * @Data: 2021/6/8 10:53 下午
  4.  */
  5. public class TestYield implements Runnable {
  6.     @Override
  7.     public void run() {
  8.         for (int i = 0; i < 500; i++) {
  9.             System.out.println("Vip Throd-->" + i);
  11.         }
  12.     }
  14.     public static void main(String[] args) throws InterruptedException {
  15.         TestYield testYield = new TestYield();
  16.         Thread thread = new Thread(testYield);
  17.         thread.start();
  18.         for (int i = 0; i < 500; i++) {
  19.             if (i == 200) {
  20.                 thread.join();//插队
  21.             }
  22.             System.out.println("main==>" + i);
  23.         }
  24.     }
  25. }

线程状态state

死亡之后的线程不可再次start

  1. /**
  2.  * @Author: haifengzuishuai
  3.  * @Data: 2021/6/9 3:34 下午
  4.  */
  5. public class TestState {
  6.     public static void main(String[] args) throws InterruptedException {
  7.         Thread thread = new Thread(() -> {
  8.             for (int i = 0; i < 5; i++) {
  9.                 try {
  10.                     Thread.sleep(1000);
  11.                 } catch (InterruptedException e) {
  12.                     e.printStackTrace();
  13.                 }
  14.             }
  15.             System.out.println("aaaaafor");
  16.         });
  17.         //观察状态
  18.         Thread.State state = thread.getState();
  19.         System.out.println(state);//NEW
  20.         //观察状态启动后
  21.         thread.start();
  22.         Thread.State state1 = thread.getState();
  23.         System.out.println(state1);//RUNNABLE
  24.         while (state != Thread.State.TERMINATED) {
  25.             Thread.sleep(1000);
  26.             state = thread.getState();//update
  27.             System.out.println(state);//TERMINATED
  28.         }
  29.     }
  30. }

线程优先级priority

  1. /**
  2.  * @Author: haifengzuishuai
  3.  * @Data: 2021/6/9 3:48 下午
  4.  */
  5. public class TestPriority {
  6.     public static void main(String[] args) {
  7.         System.out.println(Thread.currentThread().getName()+"main-->"+Thread.currentThread().getPriority());
  8.         Mypriority mypriority = new Mypriority();
  9.         Thread thread1 = new Thread(mypriority,"aaa");
  10.         Thread thread2 = new Thread(mypriority,"bbb");
  11.         Thread thread3 = new Thread(mypriority,"ccc");
  12.         Thread thread4 = new Thread(mypriority,"ddd");
  13.         Thread thread5 = new Thread(mypriority,"eee");
  14.         thread1.setPriority(5);
  15.         thread5.setPriority(10);
  16.         thread1.start();
  17.         thread2.start();
  18.         thread3.start();
  19.         thread4.start();
  20.         thread5.start();
  22.     }
  23. }
  24. class Mypriority implements Runnable{
  27.     @Override
  28.     public void run() {
  29.         System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());
  30.     }
  31. }

守护线程daemon

守护线程会守护未被守护的线程结束后，守护线程再结束

  1. /**
  2.  * @Author: haifengzuishuai
  3.  * @Data: 2021/6/9 4:07 下午
  4.  */
  5. public class TestDaemon {
  6.     public static void main(String[] args) {
  7.         God god = new God();
  8.         You you = new You();
  9.         Thread thread = new Thread(god);
  10. //        thread.setDaemon(true);
  11.         Thread thread1 = new Thread(you);
  12.         thread.start();
  13.         thread1.start();
  14.     }
  17. }
  18. class God implements Runnable{
  20.     @Override
  21.     public void run() {
  22.         while (true){
  23.             System.out.println("god");
  24.         }
  25.     }
  26. }
  27. class You implements Runnable{
  29.     @Override
  30.     public void run() {
  31.         for (int i = 0; i < 10000; i++) {
  32.             System.out.println("aaaa"+i);
  34.         }
  35.     }
  36. }

并发synchronized

多线程同时访问一个对象

每个对象都有一把锁

降低性能

性能倒置

  1. package syn;
  3. /**
  4.  * @Author: haifengzuishuai
  5.  * @Data: 2021/6/9 8:27 下午
  6.  */
  7. public class UnsafeBuyp {
  8.     public static void main(String[] args) {
  9.         BuyTicket buyTicket = new BuyTicket();
  10.         new Thread(buyTicket, "aaa").start();
  11.         new Thread(buyTicket, "bbb").start();
  12.         new Thread(buyTicket, "ccc").start();
  13.     }
  14. }
  16. class BuyTicket implements Runnable {
  17.     private int ticketNums = 5;
  18.     boolean flag = true;
  20.     @Override
  21.     public void run() {
  22.         while (flag) {
  23.             try {
  24.                 Thread.sleep(100);
  25.             } catch (InterruptedException e) {
  26.                 e.printStackTrace();
  27.             }
  28.             try {
  29.                 buy();
  30.             } catch (InterruptedException e) {
  31.                 e.printStackTrace();
  32.             }
  33.         }
  35.     }
  37.     //synchronized同步方法
  38.     private synchronized void buy() throws InterruptedException {
  39.         if (ticketNums <= 0) {
  40.             flag = false;
  41.             return;
  42.         }
  43.         System.out.println(Thread.currentThread().getName() + "拿到了" + ticketNums--);
  44.     }
  45. }

死锁

  1. Lock

线程写作