企业级 SpringBoot 教程 （二十三）异步方法

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

　架构代码如下:

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