本文通过代码来演示如果在spring boot的项目中使用多线程,也就是异步。要异步并不难,我们写的代码天天都在跟异步多线程打交道,容易让人感到迷惑的是异步的底层原理,不仅要会使用,更要熟悉其实现原理,才能更加灵活地在项目中进行运用。
首先在pom.xml中引入依赖。
<?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.zhangxueliang.demo</groupId>
<artifactId>springbootdemo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>springbootdemo</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.0.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>fluent-hc</artifactId>
<version>4.5.3</version>
</dependency>
<dependency>
<!-- jsoup HTML parser library @ https://jsoup.org/ -->
<groupId>org.jsoup</groupId>
<artifactId>jsoup</artifactId>
<version>1.10.3</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.31</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-jdbc -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!--mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.12</version>
<scope>runtime</scope>
</dependency>
<!--集成mybatis-->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.1</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!--整合freemarker-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>
<!--整合thymleaf-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<!--整合alibaba easyPOI-->
<dependency>
<groupId>cn.afterturn</groupId>
<artifactId>easypoi-base</artifactId>
<version>3.2.0</version>
</dependency>
<dependency>
<groupId>cn.afterturn</groupId>
<artifactId>easypoi-web</artifactId>
<version>3.2.0</version>
</dependency>
<dependency>
<groupId>cn.afterturn</groupId>
<artifactId>easypoi-annotation</artifactId>
<version>3.2.0</version>
</dependency>
<!-- lombok可使代码更简洁 -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<scope>provided</scope>
</dependency>
<!--热部署-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
<!--引入AOP依赖-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<!--整合MongoDB-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
<!--整合rabbitmq-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-amqp</artifactId>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
<!--使用@Slf4j注解-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
<!--爬虫相关依赖-->
<!-- jsoup HTML parser library @ https://jsoup.org/ -->
<dependency>
<groupId>org.jsoup</groupId>
<artifactId>jsoup</artifactId>
<version>1.11.2</version>
</dependency>
<!--整合POI-->
<!--<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>RELEASE</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>RELEASE</version>
</dependency>-->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.15</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml-schemas</artifactId>
<version>3.15</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>3.15</version>
</dependency>
<!-- webMagic start -->
<dependency>
<groupId>us.codecraft</groupId>
<artifactId>webmagic-core</artifactId>
<version>0.7.3</version>
</dependency>
<dependency>
<groupId>us.codecraft</groupId>
<artifactId>webmagic-extension</artifactId>
<version>0.7.3</version>
</dependency>
<dependency>
<groupId>us.codecraft</groupId>
<artifactId>webmagic-extension</artifactId>
<version>0.7.3</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- webMagic end -->
<!--引入log工程jar-->
<!--<dependency>
<groupId>com.fengyuncx.log</groupId>
<artifactId>fy-log</artifactId>
<version>0.0.1-SNAPSHOT</version>
<scope>system</scope>
<systemPath>${project.basedir}/src/main/resources/lib/fy-log-0.0.1-SNAPSHOT.jar</systemPath>
</dependency>-->
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<!--打包时将引入的本地jar打进去-->
<configuration>
<includeSystemScope>true</includeSystemScope>
</configuration>
</plugin>
</plugins>
</build>
</project>
在启动类上添加@EnableAsync注解,开启异步.注意:如果在配置类上添加了该注解,启动类上就无需添加。
@SpringBootApplication
//@EnableAsync//开启异步
public class ZxlDemoApplication {
public static void main(String[] args) {
SpringApplication.run(ZxlDemoApplication.class, args);
}
}
编写多线程配置类
/**
* 线程配置类
*/
@Configuration
@EnableAsync
public class AsyncTaskConfig implements AsyncConfigurer {
// ThredPoolTaskExcutor的处理流程
// 当池子大小小于corePoolSize,就新建线程,并处理请求
// 当池子大小等于corePoolSize,把请求放入workQueue中,池子里的空闲线程就去workQueue中取任务并处理
// 当workQueue放不下任务时,就新建线程入池,并处理请求,如果池子大小撑到了maximumPoolSize,就用RejectedExecutionHandler来做拒绝处理
// 当池子的线程数大于corePoolSize时,多余的线程会等待keepAliveTime长时间,如果无请求可处理就自行销毁
@Override
public Executor getAsyncExecutor() {
ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
taskExecutor.setCorePoolSize(50);// 核心线程数
taskExecutor.setMaxPoolSize(50);// 最大线程数
taskExecutor.setQueueCapacity(200);// 等待队列
taskExecutor.setThreadNamePrefix("zxl_taskExecutor-");//线程名称前缀
taskExecutor.initialize();
return taskExecutor;
}
@Override
public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
return null;
}
}
编写线程任务执行类
package com.zhangxueliang.demo.springbootdemo.async;
import java.util.Random;
import java.util.concurrent.Future;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.AsyncResult;
import org.springframework.stereotype.Service;
/**
* 线程执行任务类
*/
@Service
public class AsyncTaskService {
private Logger logger = LoggerFactory.getLogger(AsyncTaskService.class);
Random random = new Random();// 默认构造方法
@Async
// 表明是异步方法
// 无返回值
public void executeAsyncTask(String msg) {
System.out.println(Thread.currentThread().getName()+"开启新线程执行" + msg);
}
@Async
public Future<String> doReturn(int i){
logger.info(">>>>>>>>>>>>>>线程名>>>>>>>>>>>>>>"+Thread.currentThread().getName());
try {
// 这个方法需要调用500毫秒
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
// 消息汇总
return new AsyncResult<>(String.format("这个是第{%s}个异步调用的证书", i));
}
/**
* 异常调用返回Future
* @return
* @throws InterruptedException
*/
@Async
public Future<Long> asyncInvokeReturnFuture() throws InterruptedException {
long start = System.currentTimeMillis();
Thread.sleep(5000);
Future<Long> future = new AsyncResult<Long>((System.currentTimeMillis()-start));// Future接收返回值,这里是String类型,可以指明其他类型
return future;
}
@Async
public Future<Long> asyncInvokeReturnFuture2() throws InterruptedException {
long start = System.currentTimeMillis();
Thread.sleep(3500);
Future<Long> future = new AsyncResult<Long>((System.currentTimeMillis()-start));// Future接收返回值,这里是String类型,可以指明其他类型
return future;
}
@Async
public Future<Long> asyncInvokeReturnFuture3() throws InterruptedException {
long start = System.currentTimeMillis();
Thread.sleep(2500);
Future<Long> future = new AsyncResult<Long>((System.currentTimeMillis()-start));// Future接收返回值,这里是String类型,可以指明其他类型
return future;
}
}
编写测试类,也就是调用多线程任务。
@RunWith(SpringRunner.class)
@SpringBootTest
public class ZxlTest {
private Logger logger = LoggerFactory.getLogger(ZxlTest.class);
@Autowired
private AsyncTaskService asyncTaskService;
@Test
public void testAsync(){
// String msg="测试测试";
// System.out.println(Thread.currentThread().getName()+":"+msg);
// asyncTaskService.executeAsyncTask(msg);
try {
long start = System.currentTimeMillis();
Future<Long> future = asyncTaskService.asyncInvokeReturnFuture();
Future<Long> future2 = asyncTaskService.asyncInvokeReturnFuture2();
Future<Long> future3 = asyncTaskService.asyncInvokeReturnFuture3();
Long l1 = future.get();//5000
Long l2 = future2.get();//3500
Long l3 = future3.get();//2500
System.out.println(Thread.currentThread().getName()+"*************************************");
System.out.println(Thread.currentThread().getName()+(l1+l2+l3 ));
System.out.println(Thread.currentThread().getName()+"-------------------------------------");
System.out.println(Thread.currentThread().getName()+(System.currentTimeMillis()-start));
System.out.println(Thread.currentThread().getName()+"+++++++++++++++++++++++++++++++++++++");
} catch (Exception e) {
e.printStackTrace();
}
}
}