Spring Boot教程(三十二)异步方法
2018-02-27 00:00
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创建工程
在pom文件引入相关依赖:<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> </dependency>
创建一个接收数据的实体:
@JsonIgnoreProperties(ignoreUnknown=true) public class User { private String name; private String blog; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getBlog() { return blog; } public void setBlog(String blog) { this.blog = blog; } @Override public String toString() { return "User [name=" + name + ", blog=" + blog + "]"; } }
创建一个请求的 githib的service:
@Service public class GitHubLookupService { private static final Logger logger = LoggerFactory.getLogger(GitHubLookupService.class); private final RestTemplate restTemplate; public GitHubLookupService(RestTemplateBuilder restTemplateBuilder) { this.restTemplate = restTemplateBuilder.build(); } @Async public Future<User> findUser(String user) throws InterruptedException { logger.info("Looking up " + user); String url = String.format("https://api.github.com/users/%s", user); User results = restTemplate.getForObject(url, User.class); // Artificial delay of 1s for demonstration purposes Thread.sleep(1000L); return new AsyncResult<>(results); } }
通过,RestTemplate去请求,另外加上类@Async 表明是一个异步任务。
开启异步任务:
@SpringBootApplication @EnableAsync public class Application extends AsyncConfigurerSupport { public static void main(String[] args) { SpringApplication.run(Application.class, args); } @Override public Executor getAsyncExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setCorePoolSize(2); executor.setMaxPoolSize(2); executor.setQueueCapacity(500); executor.setThreadNamePrefix("GithubLookup-"); executor.initialize(); return executor; } }
通过@EnableAsync开启异步任务;并且配置AsyncConfigurerSupport,比如最大的线程池为2.
测试
测试代码如下:@Component public class AppRunner implements CommandLineRunner { private static final Logger logger = LoggerFactory.getLogger(AppRunner.class); private final GitHubLookupService gitHubLookupService; public AppRunner(GitHubLookupService gitHubLookupService) { this.gitHubLookupService = gitHubLookupService; } @Override public void run(String... args) throws Exception { // Start the clock long start = System.currentTimeMillis(); // Kick of multiple, asynchronous lookups Future<User> page1 = gitHubLookupService.findUser("PivotalSoftware"); Future<User> page2 = gitHubLookupService.findUser("CloudFoundry"); Future<User> page3 = gitHubLookupService.findUser("Spring-Projects"); // Wait until they are all done while (!(page1.isDone() && page2.isDone() && page3.isDone())) { Thread.sleep(10); //10-millisecond pause between each check } // Print results, including elapsed time logger.info("Elapsed time: " + (System.currentTimeMillis() - start)); logger.info("--> " + page1.get()); logger.info("--> " + page2.get()); logger.info("--> " + page3.get()); } }
启动程序,控制台会打印:
2017-04-30 13:11:10.351 INFO 1511 — [ GithubLookup-1] com.forezp.service.GitHubLookupService : Looking up PivotalSoftware 2017-04-30 13:11:10.351 INFO 1511 — [ GithubLookup-2] com.forezp.service.GitHubLookupService : Looking up CloudFoundry 2017-04-30 13:11:13.144 INFO 1511 — [ GithubLookup-2] com.forezp.service.GitHubLookupService : Looking up Spring-Projects
耗时:3908
分析:可以卡的前面2个方法分别在GithubLookup-1 和GithubLookup-2执行,第三个在GithubLookup-2执行,注意因为在配置线程池的时候最大线程为2.如果你把线程池的个数为3的时候,耗时减少。
如果去掉@Async,你会发现,执行这三个方法都在main线程中执行。耗时总结,如下:
2017-04-30 13:13:00.934 INFO 1527 — [ main] com.forezp.service.GitHubLookupService : Looking up PivotalSoftware 2017-04-30 13:13:03.571 INFO 1527 — [ main] com.forezp.service.GitHubLookupService : Looking up CloudFoundry 2017-04-30 13:13:04.865 INFO 1527 — [ main] com.forezp.service.GitHubLookupService : Looking up Spring-Projects
源码来源
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