Spring Boot教程(三十二)异步方法

2018-03-01 11:17:15来源:oschina作者:abbie265人点击

分享
创建工程

在pom文件引入相关依赖:



org.springframework.boot
spring-boot-starter


org.springframework
spring-web


com.fasterxml.jackson.core
jackson-databind

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 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 page1 = gitHubLookupService.findUser("PivotalSoftware");
Future page2 = gitHubLookupService.findUser("CloudFoundry");
Future 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

最新文章

123

最新摄影

闪念基因

微信扫一扫

第七城市微信公众平台