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Java騷操作之CountDownLatch代碼詳解

更新時間：2021年02月19日 10:45:39 作者：Java Pro

這篇文章主要介紹了Java騷操作之CountDownLatch代碼詳解,本文通過實例圖文相結(jié)合給大家介紹的非常詳細(xì)，對大家的學(xué)習(xí)或工作具有一定的參考借鑒價值，需要的朋友可以參考下

簡述

用來干嘛的？當(dāng)你在方法中調(diào)用了多個線程，對數(shù)據(jù)庫進(jìn)行了一些不為人知的操作后，還有一個操作需要留到前者都執(zhí)行完的重頭戲，就需要用到 CountDownLatch 了

實踐代碼

package com.github.gleans;

import java.util.concurrent.CountDownLatch;

public class TestCountDownLatch {

  public static void main(String[] args) throws InterruptedException {
    CountDownLatch latch = new CountDownLatch(3);
    new KeyPass(1000L, "thin jack", latch).start();
    new KeyPass(2000L, "noral jack", latch).start();
    new KeyPass(3000L, "fat jack", latch).start();
    latch.await();
    System.out.println("此處對數(shù)據(jù)庫進(jìn)行最后的插入操作~");
  }

  static class KeyPass extends Thread {

    private long times;

    private CountDownLatch countDownLatch;

    public KeyPass(long times, String name, CountDownLatch countDownLatch) {
      super(name);
      this.times = times;
      this.countDownLatch = countDownLatch;
    }

    @Override
    public void run() {
      try {
        System.out.println("操作人：" + Thread.currentThread().getName()
            + "對數(shù)據(jù)庫進(jìn)行插入，持續(xù)時間：" + this.times / 1000 + "秒");
        Thread.sleep(times);
        countDownLatch.countDown();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
  }
}

圖解

使用await()提前結(jié)束操作

package com.github.gleans;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

public class TestCountDownLatch {

  public static void main(String[] args) throws InterruptedException {
    CountDownLatch latch = new CountDownLatch(3);
    new KeyPass(2000L, "公司一", latch).start();
    new KeyPass(3000L, "公司二", latch).start();
    new KeyPass(5000L, "公司三", latch).start();
    latch.await(2, TimeUnit.SECONDS);
    System.out.println("~~~賈總PPT巡演~~~~");
    System.out.println("~~~~融資完成，撒花~~~~");
  }

  static class KeyPass extends Thread {

    private long times;

    private CountDownLatch countDownLatch;

    public KeyPass(long times, String name, CountDownLatch countDownLatch) {
      super(name);
      this.times = times;
      this.countDownLatch = countDownLatch;
    }

    @Override
    public void run() {
      try {
        Thread.sleep(times);
        System.out.println("負(fù)責(zé)人：" + Thread.currentThread().getName()
            + "開始工作，持續(xù)時間：" + this.times / 1000 + "秒");
        countDownLatch.countDown();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
  }
}

假設(shè)公司一、公司二、公司三各需要2s、3s、5s來完成工作，賈總等不了，只能等2s，那么就設(shè)置await的超時時間