轉載：SpringBoot非官方教程 | 第二十三篇： 非同步方法
轉載：https://blog.csdn.net/forezp/article/details/71024169
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>
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
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 + "]"; } }
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
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); } }
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
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;
}
}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
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());
}
}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
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/async-method/
原始碼下載
https://github.com/forezp/SpringBootLearning
優秀文章推薦：
- 更多springboot 教程：springBoot非官方教程 | 文章彙總