@Async异步调用
就不解释什么是异步调用了，Spring Boot中进行异步调用很简单
1.通过使用@Async注解就能简单的将原来的同步函数变为异步函数
package com.winner.service; import org.springframework.scheduling.annotation.Async; import org.springframework.stereotype.Service; import java.util.concurrent.TimeUnit; /** * @author winner_0715 * @date 2018/12/06 */ @Service public class TaskServer { @Async public void doTaskA() throws InterruptedException { System.out.println("TaskA thread name->" + Thread.currentThread().getName()); Long startTime = System.currentTimeMillis(); TimeUnit.SECONDS.sleep(2); Long endTime = System.currentTimeMillis(); System.out.println("TaskA 耗时：" + (endTime - startTime)); } @Async public void doTaskB() throws InterruptedException { System.out.println("TaskB thread name->" + Thread.currentThread().getName()); Long startTime = System.currentTimeMillis(); TimeUnit.SECONDS.sleep(2); Long endTime = System.currentTimeMillis(); System.out.println("TaskB耗时：" + (endTime - startTime)); } }
为了让@Async注解能够生效，还需要在Spring Boot的主程序中配置@EnableAsync，如下所示：
package com.winner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.scheduling.annotation.EnableAsync; /** * @author winner_0715 * @date 2018/12/06 */ @SpringBootApplication @EnableAsync public class SpringBootAsyncApplication { public static void main(String[] args) { SpringApplication.run(SpringBootAsyncApplication.class, args); } }
注： @Async所修饰的函数不要定义为static类型，这样异步调用不会生效
测试
package com.winner.web; import com.winner.service.TaskServer; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; import javax.annotation.Resource; /** * @author winner_0715 * @description: * @date 2018/12/6 */ @RestController public class HelloController { @Resource private TaskServer taskServer; @GetMapping("/async") public String testAsync() throws Exception { System.out.println("主线程 name -->" + Thread.currentThread().getName()); taskServer.doTaskA(); taskServer.doTaskB(); return "Hello World"; } }
任务线程和主线程的名称不同，表明是异步执行的！
自定义线程池
前面介绍使用@Async注解来实现异步调用了。对于这些异步执行的控制是我们保障自身应用健康的基本技能。下面介绍通过自定义线程池的方式来控制异步调用的并发。
定义线程池
第一步，定义一个线程池，比如：
package com.winner.threadpool; import com.google.common.util.concurrent.ThreadFactoryBuilder; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import java.util.concurrent.Executor; import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.ThreadFactory; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; /** * @author winner_0715 */ @Configuration public class ThreadPoolExecutorConfig { private static final int THREADS = Runtime.getRuntime().availableProcessors() + 1; final ThreadFactory threadFactory = new ThreadFactoryBuilder() // -%d不要少
.setNameFormat("async-task-name-%d") .setDaemon(true) .build(); @Bean("taskExecutor") public Executor taskExecutor() { return new ThreadPoolExecutor(THREADS, 2 * THREADS, 5, TimeUnit.SECONDS, new LinkedBlockingQueue<>(1024), threadFactory, (r, executor) -> { // 打印日志,添加监控等
System.out.println("task is rejected!"); }); } }
上面我们通过使用ThreadPoolExecutor创建了一个线程池
使用线程池
在定义了线程池之后，我们如何让异步调用的执行任务使用这个线程池中的资源来运行呢？方法非常简单，我们只需要在@Async注解中指定线程池名即可，比如：
package com.winner.service; import org.springframework.scheduling.annotation.Async; import org.springframework.stereotype.Service; import java.util.concurrent.TimeUnit; /** * @author winner_0715 * @date 2018/12/06 */ @Service public class TaskServer { @Async("taskExecutor") public void doTaskA() throws InterruptedException { System.out.println("MsgServer send A thread name->" + Thread.currentThread().getName()); Long startTime = System.currentTimeMillis(); TimeUnit.SECONDS.sleep(2); Long endTime = System.currentTimeMillis(); System.out.println("MsgServer send A 耗时：" + (endTime - startTime)); } @Async("taskExecutor") public void doTaskB() throws InterruptedException { System.out.println("MsgServer send B thread name->" + Thread.currentThread().getName()); Long startTime = System.currentTimeMillis(); TimeUnit.SECONDS.sleep(2); Long endTime = System.currentTimeMillis(); System.out.println("MsgServer send B耗时：" + (endTime - startTime)); } }
测试
package com.winner.web; import com.winner.service.TaskServer; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; import javax.annotation.Resource; /** * @author winner_0715 * @description: * @date 2018/12/6 */ @RestController public class HelloController { @Resource private TaskServer taskServer; @GetMapping("/async") public String testAsync() throws Exception { System.out.println("主线程 name -->" + Thread.currentThread().getName()); taskServer.doTaskA(); taskServer.doTaskB(); return "Hello World"; } }
测试结果：
主线程 name -->http-nio-8080-exec-1 MsgServer send A thread name->async-task-name-0 MsgServer send B thread name->async-task-name-1 MsgServer send A 耗时：2001 MsgServer send B耗时：2001