CountDownLatch简单使用
如何保证主线程在副线程执行结束后才会执行结束，这里使用CountDownLatch
//设置三个线程需要执行 CountDownLatch latch = new CountDownLatch(3);
//每调用一次数值减1,当count为0,代表全部线程执行结束 latch.countDown();
//当设置的线程未执行结束，保持等待状态 latch.await();
因为我设置的数量是3,但是只使用了两个，所以一直处于等待的状态
pom文件
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.java</groupId>
<artifactId>test-study</artifactId>
<version>1.0-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.1.RELEASE</version>
<relativePath/>
</parent>
<dependencies>
<!--tomcat容器-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!--lombok依赖-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.16</version>
</dependency>
<!--引入junit单元测试依赖-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<!--判断空的用法 -->
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
<version>2.6</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.oracle.database.jdbc/ojdbc8 -->
<dependency>
<groupId>com.oracle.database.jdbc</groupId>
<artifactId>ojdbc8</artifactId>
<version>12.2.0.1</version>
</dependency>
<!--springboot整合mybatis-->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.2</version>
</dependency>
<!--添加fastjson依赖-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.70</version>
</dependency>
<!-- 热部署模块 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional> <!-- 这个需要为 true 热部署才有效 -->
</dependency>
<!--ThreadFactoryBuilder的依赖包,多线程使用-->
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>30.1-jre</version>
</dependency>
<!--Lists.partition要用的依赖-->
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>21.0</version>
</dependency>
<!--ListUtils.partition使用的依赖-->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>4.4</version>
</dependency>
<!--操作redis的依赖-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-pool2</artifactId>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.9</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
<finalName>study</finalName>
</build>
</project>
server.port=2001 logging.level.com.java.test=debug logging.level.web=debug spring.devtools.add-properties=false
package com.java.test;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
* @Description:
* @Author: Yourheart
* @Create: 2022/10/20 15:32
*/
@SpringBootApplication
public class TestApplication {
public static void main(String[] args) {
SpringApplication.run(TestApplication.class,args);
}
}
package com.java.test.countdownlatch;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
import java.util.concurrent.CountDownLatch;
/**
* @author Yourheart
* @Create: 2022/12/22 11:41
*/
@Slf4j
/**
* 主要用于标记配置类，兼备Component的效果。
*/
@Configuration
/**
* 开启定时任务
*/
@EnableScheduling
public class CountDownLatchDemo {
/**
* 设置三个线程需要执行
*/
public static CountDownLatch latch = new CountDownLatch(3);
/**
* 每隔15秒执行一次
*/
//@Scheduled(cron = "0/15 * * * * *")
//每天的17点45分0秒执行
@Scheduled(cron = "0 45 17 * * *")
@Async
public void endTest() throws InterruptedException {
long count = latch.getCount();
log.info("count:{}",count);
latch.countDown();
}
}
package com.java.test.countdownlatch;
import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.CountDownLatch;
/**
* @Description:
* @Author: Yourheart
* @Create: 2022/12/22 16:29
*/
@Slf4j
public class CountDownLatchThread implements Runnable {
private final CountDownLatch latch;
public CountDownLatchThread(String name, CountDownLatch latch) {
this.latch = latch;
}
@Override
public void run() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
log.info(Thread.currentThread().getName() + "线程结束");
//每调用一次数值减1,当count为0,代表全部线程执行结束
latch.countDown();
}
}
package com.java.test.countdownlatch;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.time.StopWatch;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* @Description:
* @Author: Yourheart
* @Create: 2022/12/22 17:36
*/
@RestController
@Slf4j
public class CountDownLatchController {
@GetMapping("/countDownLatchTest")
public String countDownLatchTest() throws InterruptedException {
StopWatch started = StopWatch.createStarted();
long latchCount = CountDownLatchDemo.latch.getCount();
log.info("latchCount:{}",latchCount);
for(int i = 0; i<latchCount-1; i++){
CountDownLatchThread latchThread = new CountDownLatchThread("线程"+i,CountDownLatchDemo.latch);
new Thread(latchThread).start();
}
//当设置的线程未执行结束，保持等待状态
CountDownLatchDemo.latch.await();
log.info("耗时:{}",started.toString());
return started.toString();
}
}
