Spring Boot使用@Async实现异步调用
原文:http://blog.csdn.net/a286352250/article/details/53157822
项目GitHub地址 :
https://github.com/FrameReserve/TrainingBoot
Spring Boot(十)使用@Async实现异步调用 ,标记地址:
https://github.com/FrameReserve/TrainingBoot/releases/tag/0.0.10
Spring Boot启动类,增加@EnableAsync注解配置:
src/main/java/com/training/SpringBootServlet.java
- package com.training;
- import org.springframework.boot.SpringApplication;
- import org.springframework.boot.autoconfigure.SpringBootApplication;
- import org.springframework.boot.builder.SpringApplicationBuilder;
- import org.springframework.boot.web.support.SpringBootServletInitializer;
- import org.springframework.scheduling.annotation.EnableAsync;
- @SpringBootApplication
- @EnableAsync
- public class SpringBootServlet extends SpringBootServletInitializer {
- // jar启动
- public static void main(String[] args) {
- SpringApplication.run(SpringBootServlet.class, args);
- }
- // tomcat war启动
- @Override
- protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
- return application.sources(SpringBootServlet.class);
- }
- }
测试:
增加异步方法Service,线程休眠:
- package com.training.async.service.impl;
- import java.util.Random;
- import java.util.concurrent.Future;
- import org.springframework.scheduling.annotation.Async;
- import org.springframework.scheduling.annotation.AsyncResult;
- import org.springframework.stereotype.Service;
- import com.training.async.service.DemoAsyncService;
- @Service
- public class DemoAsyncServiceImpl implements DemoAsyncService {
- public static Random random =new Random();
- @Async
- public Future<String> doTaskOne() throws Exception {
- System.out.println("开始做任务一");
- long start = System.currentTimeMillis();
- Thread.sleep(random.nextInt(10000));
- long end = System.currentTimeMillis();
- System.out.println("完成任务一,耗时:" + (end - start) + "毫秒");
- return new AsyncResult<>("任务一完成");
- }
- @Async
- public Future<String> doTaskTwo() throws Exception {
- System.out.println("开始做任务二");
- long start = System.currentTimeMillis();
- Thread.sleep(random.nextInt(10000));
- long end = System.currentTimeMillis();
- System.out.println("完成任务二,耗时:" + (end - start) + "毫秒");
- return new AsyncResult<>("任务二完成");
- }
- @Async
- public Future<String> doTaskThree() throws Exception {
- System.out.println("开始做任务三");
- long start = System.currentTimeMillis();
- Thread.sleep(random.nextInt(10000));
- long end = System.currentTimeMillis();
- System.out.println("完成任务三,耗时:" + (end - start) + "毫秒");
- return new AsyncResult<>("任务三完成");
- }
- }
调用异步测试测试,查看控制台输出执行顺序:
- package com.training.async.controller;
- import io.swagger.annotations.ApiOperation;
- import java.util.concurrent.Future;
- import javax.annotation.Resource;
- import org.springframework.web.bind.annotation.RequestMapping;
- import org.springframework.web.bind.annotation.RequestMethod;
- import org.springframework.web.bind.annotation.ResponseBody;
- import org.springframework.web.bind.annotation.RestController;
- import com.training.async.service.DemoAsyncService;
- import com.training.core.dto.ResultDataDto;
- @RestController
- @RequestMapping(value="/async")
- public class DemoAsyncController {
- @Resource
- private DemoAsyncService demoAsyncService;
- /**
- * 测试异步方法调用顺序
- */
- @ApiOperation(value="测试异步方法调用顺序", notes="getEntityById")
- @RequestMapping(value = "/getTestDemoAsync", method = RequestMethod.GET)
- public @ResponseBody ResultDataDto getEntityById() throws Exception {
- long start = System.currentTimeMillis();
- Future<String> task1 = demoAsyncService.doTaskOne();
- Future<String> task2 = demoAsyncService.doTaskTwo();
- Future<String> task3 = demoAsyncService.doTaskThree();
- while(true) {
- if(task1.isDone() && task2.isDone() && task3.isDone()) {
- // 三个任务都调用完成,退出循环等待
- break;
- }
- Thread.sleep(1000);
- }
- long end = System.currentTimeMillis();
- System.out.println("任务全部完成,总耗时:" + (end - start) + "毫秒");
- return ResultDataDto.addSuccess();
- }
- }
原文:http://blog.csdn.net/v2sking/article/details/72795742
什么是异步调用?
异步调用是相对于同步调用而言的,同步调用是指程序按预定顺序一步步执行,每一步必须等到上一步执行完后才能执行,异步调用则无需等待上一步程序执行完即可执行。
如何实现异步调用?
多线程,这是很多人第一眼想到的关键词,没错,多线程就是一种实现异步调用的方式。
在非spring目项目中我们要实现异步调用的就是使用多线程方式,可以自己实现Runable接口或者集成Thread类,或者使用jdk1.5以上提供了的Executors线程池。
StrngBoot中则提供了很方便的方式执行异步调用。
按照官方示例开撸
代码入下
maven依赖:
- <parent>
- <groupId>org.springframework.boot</groupId>
- <artifactId>spring-boot-starter-parent</artifactId>
- <version>1.5.3.RELEASE</version>
- </parent>
- <dependencies>
- <dependency>
- <groupId>org.springframework.boot</groupId>
- <artifactId>spring-boot-starter-web</artifactId>
- </dependency>
- </dependencies>
启动类:添加@EnableAsync注解
- @SpringBootApplication
- @EnableAsync
- public class Application{
- public static void main(String[] args) {
- SpringApplication.run(Application.class, args);
- }
- }
Controller
只需在需要异步执行方法上添加@Async注解
- @RestController
- @RequestMapping("")
- public class AsyncTaskController {
- @RequestMapping("")
- public String doTask() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- this.task1();
- this.task2();
- this.task3();
- long currentTimeMillis1 = System.currentTimeMillis();
- return "task任务总耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms";
- }
- @Async
- public void task1() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(1000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task1任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- }
- @Async
- public void task2() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(2000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task2任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- }
- @Async
- public void task3() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(3000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task3任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- }
- }
main函数运行spirngboot项目,启动完成后浏览器访问:
http://localhost:8080/
控制台:
- task1任务耗时:1012ms
- task2任务耗时:2009ms
- task3任务耗时:3004ms
等了一段浏览器时候输出入下:
- task任务总耗时:6002ms
异步并没有执行!
难道是代码写错了?反复检查了好几遍,并没有发现什么明显错误,想起spring对@Transactional注解时也有类似问题,spring扫描时具有@Transactional注解方法的类时,是生成一个代理类,由代理类去开启关闭事务,而在同一个类中,方法调用是在类体内执行的,spring无法截获这个方法调用。
豁然开朗,将异步任务单独放到一个类中,调整代码入下:
Controller
- @RequestMapping("")
- @RestController
- public class AsyncTaskController {
- @Autowired
- private AsyncTask asyncTask;
- @RequestMapping("")
- public String doTask() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- asyncTask.task1();
- asyncTask.task2();
- asyncTask.task3();
- long currentTimeMillis1 = System.currentTimeMillis();
- return "task任务总耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms";
- }
- }
异步任务类
- @Component
- public class AsyncTask {
- @Async
- public void task1() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(1000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task1任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- }
- @Async
- public void task2() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(2000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task2任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- }
- @Async
- public void task3() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(3000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task3任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- }
- }
控制台:
- task1任务耗时:1012ms
- task2任务耗时:2009ms
- task3任务耗时:3004ms
访问浏览器结果入下:
- task任务总耗时:19ms
异步调用成功!
如何知道三个异步任务什么时候执行完,执行的结果怎样呢?可以采用添加Fature回调方式判断
代码入下:
异步任务类
- @Component
- public class AsyncTask {
- @Async
- public Future<String> task1() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(1000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task1任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- return new AsyncResult<String>("task1执行完毕");
- }
- @Async
- public Future<String> task2() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(2000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task2任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- return new AsyncResult<String>("task2执行完毕");
- }
- @Async
- public Future<String> task3() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Thread.sleep(3000);
- long currentTimeMillis1 = System.currentTimeMillis();
- System.out.println("task3任务耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms");
- return new AsyncResult<String>("task3执行完毕");
- }
- }
Controller
- @RequestMapping("")
- @RestController
- public class AsyncTaskController {
- @Autowired
- private AsyncTask asyncTask;
- @RequestMapping("")
- public String doTask() throws InterruptedException{
- long currentTimeMillis = System.currentTimeMillis();
- Future<String> task1 = asyncTask.task1();
- Future<String> task2 = asyncTask.task2();
- Future<String> task3 = asyncTask.task3();
- String result = null;
- for (;;) {
- if(task1.isDone() && task2.isDone() && task3.isDone()) {
- // 三个任务都调用完成,退出循环等待
- break;
- }
- Thread.sleep(1000);
- }
- long currentTimeMillis1 = System.currentTimeMillis();
- result = "task任务总耗时:"+(currentTimeMillis1-currentTimeMillis)+"ms";
- return result;
- }
- }
控制台输出:
- task1任务耗时:1000ms
- task2任务耗时:2001ms
- task3任务耗时:3001ms
浏览器输出:
- <span style="font-family: Simsun; font-size: 14px;">task任务总耗时:4015ms</span>
异步调用成功,并且在所有任务都完成时程序才返回了结果!
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