執行緒建立

• 繼承Thread類

  package com.yeyue.demo01;
  ​
  //建立執行緒方式一：繼承Thread類，重寫run（）方法，呼叫start開啟執行緒
  ​
  //執行緒開始不一定立即執行，由cpu排程
  ​
  public class TestThread1 extends Thread {
    @Override
    public void run() {
      //run方法執行緒體
      for (int i = 0; i < 20; i++) {
        System.out.println("我在看程式碼---"+i);
       }
     }
  ​
    public static void main(String[] args) {
      //main 執行緒，主執行緒
  ​
      //建立一個執行緒物件
      TestThread1 testThread1 = new TestThread1();
  ​
      //呼叫start（）方法開啟執行緒
      testThread1.start();
  ​
      for (int i = 0; i < 100; i++) {
        System.out.println("我在學習多執行緒----" + i);
       }
     }
  }
   
  

• 實現Runnable介面

  多執行緒下載圖片

  package com.yeyue.demo01;
  ​
  import org.apache.commons.io.FileUtils;
  ​
  import java.io.File;
  import java.io.IOException;
  import java.net.URL;
  ​
  //練習Thread，實現多執行緒同步下載圖片
  public class TestThread2 implements Runnable {
    private String url; //圖片下載的url
    private String name; //下載的圖片儲存的圖片名字
  ​
  ​
    public TestThread2(String url,String name){
      this.url = url;
      this.name = name;
     }
  ​
    //下載圖片的執行體
    @Override
    public void run() {
      WebDownloader webDownloader = new WebDownloader();
      webDownloader.downloader(url,name);
      System.out.println("下載了檔名：" + name);
     }
  ​
    public static void main(String[] args) {
      TestThread2 t1 = new TestThread2("https://img2.baidu.com/it/u=2253502056,189588800&fm=26&fmt=auto&gp=0.jpg","1.jpg");
      TestThread2 t2 = new TestThread2("https://img2.baidu.com/it/u=3529414605,308711291&fm=26&fmt=auto&gp=0.jpg","2.jpg");
      TestThread2 t3 = new TestThread2("https://img1.baidu.com/it/u=1863405005,3705892836&fm=26&fmt=auto&gp=0.jpg","3.jpg");
  ​
      new Thread(t1).start();
      new Thread(t2).start();
      new Thread(t3).start();
  ​
     }
  ​
  }
  ​
  //下載器
  class WebDownloader{
    //下載方法
    public void downloader(String url,String name){
      try {
        FileUtils.copyURLToFile(new URL(url),new File(name));
       } catch (IOException e) {
        e.printStackTrace();
        System.out.println("IO異常，downloader方法出現問題");
       }
     }
  }
   
  

  買票

  package com.yeyue.demo01;
  ​
  //多個執行緒同時操作一個物件
  //買火車票的例子
  ​
  //多個執行緒操作同一個資源的情況下，資源不安全了
  public class TestThread4 implements Runnable {
  ​
    //票數
    private int ticketNums =10;
  ​
    @Override
    public void run() {
      while (true){
        if(ticketNums <= 0){
          break;
         }
        try {
          Thread.sleep(200);
         } catch (InterruptedException e) {
          e.printStackTrace();
         }
        System.out.println(Thread.currentThread().getName()+"-->拿到了第"+ticketNums--+"票");
       }
     }
  ​
    public static void main(String[] args) {
      TestThread4 ticket = new TestThread4();
  ​
      new Thread(ticket,"小明").start();
      new Thread(ticket,"老師").start();
      new Thread(ticket,"黃牛黨").start();
     }
  }
   
  

• 實現Callable介面

  package com.yeyue.demo01;
  ​
  import org.apache.commons.io.FileUtils;
  ​
  import java.io.File;
  import java.io.IOException;
  import java.net.URL;
  import java.util.concurrent.*;
  ​
  public class TestCallable implements Callable<Boolean> {
    private String url; //圖片下載的url
    private String name; //下載的圖片儲存的圖片名字
  ​
  ​
    public TestCallable(String url,String name){
      this.url = url;
      this.name = name;
     }
  ​
    //下載圖片的執行體
    @Override
    public Boolean call() {
      WebDownloader1 webDownloader1 = new WebDownloader1();
      webDownloader1.downloader1(url,name);
      System.out.println("下載了檔名：" + name);
      return true;
     }
  ​
    public static void main(String[] args) throws ExecutionException, InterruptedException {
      TestCallable t1 = new TestCallable("https://img2.baidu.com/it/u=2253502056,189588800&fm=26&fmt=auto&gp=0.jpg","1.jpg");
      TestCallable t2 = new TestCallable("https://img2.baidu.com/it/u=3529414605,308711291&fm=26&fmt=auto&gp=0.jpg","2.jpg");
      TestCallable t3 = new TestCallable("https://img1.baidu.com/it/u=1863405005,3705892836&fm=26&fmt=auto&gp=0.jpg","3.jpg");
  ​
      //建立執行服務
      ExecutorService ser = (ExecutorService) Executors.newFixedThreadPool(3);
  ​
      //提交執行：
      Future<Boolean> r1 = ser.submit(t1);
      Future<Boolean> r2 = ser.submit(t2);
      Future<Boolean> r3 = ser.submit(t3);
  ​
      //獲取結果
      boolean rs1 = r1.get();
      boolean rs2 = r2.get();
      boolean rs3 = r3.get();
  ​
      System.out.println(rs1);
      System.out.println(rs2);
      System.out.println(rs3);
  ​
      //關閉服務
      ser.shutdownNow();
     }
  ​
  }
  ​
  //下載器
  class WebDownloader1 {
    //下載方法
    public void downloader1(String url, String name) {
      try {
        FileUtils.copyURLToFile(new URL(url), new File(name));
       } catch (IOException e) {
        e.printStackTrace();
        System.out.println("IO異常，downloader方法出現問題");
       }
     }
  }

• 模擬龜兔賽跑

  package com.yeyue.demo01;
  ​
  //模擬龜兔賽跑
  public class Race implements Runnable{
  ​
    private static String winner;
  ​
    @Override
    public void run() {
      for (int i = 0; i <= 100; i++) {
  ​
        if(Thread.currentThread().getName().equals("兔子") && i%10==0){
          try {
            Thread.sleep(1);
           } catch (InterruptedException e) {
            e.printStackTrace();
           }
         }
  ​
        //判斷遊戲是否結束
        boolean flag = gameOver(i);
        if(flag){
          break;
         }
  ​
  ​
        System.out.println(Thread.currentThread().getName()+"跑了"+i+"步");
       }
     }
  ​
    private boolean gameOver(int steps){
      if(winner!=null){
        return true;
       }{
        if(steps>=100){
          winner = Thread.currentThread().getName();
          System.out.println("winner is " + winner);
          return true;
         }
       }
      return false;
     }
  ​
    public static void main(String[] args) {
      Race race = new Race();
  ​
      new Thread(race,"兔子").start();
      new Thread(race,"烏龜").start();
     }
  ​
  }