Spring Boot教程10——多线程

Spring通过任务执行器（TaskExecutor）来实现多线程和并发编程。使用ThreadPoolTaskExecutor可实现一个基于线程池的TaskExcutor。而实际开发中任务一般是非阻碍的，即异步的，所以我们要在配置类中通过@EnableAsync开启对异步任务的支持，并通过在实际执行的Bean的方法中通过使用@Async注解来声明其是一个异步任务。

示例

1>.配置类

package com.wisely.highlight_spring4.ch3.taskexecutor;

import java.util.concurrent.Executor;

import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.AsyncConfigurer;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
@Configuration
@ComponentScan("com.wisely.highlight_spring4.ch3.taskexecutor")
@EnableAsync //开启异步任务支持
public class TaskExecutorConfig implements AsyncConfigurer{//实现AsyncConfigurer接口

    @Override
    public Executor getAsyncExecutor() {//实现AsyncConfigurer接口并重写getAsyncExecutor方法，并返回一个ThreadPoolTaskExecutor，这样我们就获得了一个基于线程池TaskExecutor
         ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
            taskExecutor.setCorePoolSize(5);
            taskExecutor.setMaxPoolSize(10);
            taskExecutor.setQueueCapacity(25);
            taskExecutor.initialize();
            return taskExecutor;
    }

    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return null;
    }

}

2>.任务执行类

package com.wisely.highlight_spring4.ch3.taskexecutor;

import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;
@Service
public class AsyncTaskService {

    @Async //通过@Async注解表明该方法是一个异步方法，如果注解在类级别，则表明该类所有的方法都是异步方法，而这里的方法自动被注入使用ThreadPoolTaskExecutor作为TaskExecutor
    public void executeAsyncTask(Integer i){
        System.out.println("?执行异步任务: "+i);
    }

    @Async
    public void executeAsyncTaskPlus(Integer i){
        System.out.println("?执行异步任务+1: "+(i+1));
    }

}

3>.运行

package com.wisely.highlight_spring4.ch3.taskexecutor;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {

    public static void main(String[] args) {
         AnnotationConfigApplicationContext context =
                    new AnnotationConfigApplicationContext(TaskExecutorConfig.class);

         AsyncTaskService asyncTaskService = context.getBean(AsyncTaskService.class);

         for(int i =0 ;i<10;i++){
             asyncTaskService.executeAsyncTask(i);
             asyncTaskService.executeAsyncTaskPlus(i);
            }
            context.close();
    }
}

结果是并发执行而不是顺序执行的。