這篇文章主要介紹在springboot 使用非同步方法,去請求github api.
建立工程
在pom檔案引入相關依賴:
<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>
建立一個接收資料的實體:
@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 + "]";
}
}
建立一個請求的 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);
}
}
通過,RestTemplate去請求,另外加上類@Async 表明是一個非同步任務。
開啟非同步任務:
@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;
}
}
通過@EnableAsync開啟非同步任務;並且配置AsyncConfigurerSupport,比如最大的執行緒池為2.
測試
測試程式碼如下:
@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());
}
}
啟動程式,控制檯會列印:
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
耗時:3908
分析:可以卡的前面2個方法分別在GithubLookup-1 和GithubLookup-2執行,第三個在GithubLookup-2執行,注意因為在配置執行緒池的時候最大執行緒為2.如果你把執行緒池的個數為3的時候,耗時減少。
如果去掉@Async,你會發現,執行這三個方法都在main執行緒中執行。耗時總結,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
耗時:5261
通過這一個小的栗子,你應該對非同步任務有了一定的瞭解。
參考資料
https://spring.io/guides/gs/a…