参考链接：Spring官方示例

User.java

package hello;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@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 + "]";

    }

}

@Async

1. 添加 @Async注解；
2. 返回值声明为： CompletableFuture
3. 配置 @Component 或 @ Service 等，保证可以 组件扫描到

package hello;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.boot.web.client.RestTemplateBuilder;

import org.springframework.scheduling.annotation.Async;

import org.springframework.stereotype.Service;

import org.springframework.web.client.RestTemplate;

import java.util.concurrent.CompletableFuture;

@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 CompletableFuture<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 CompletableFuture.completedFuture(results);

    }

}

自定义 Executor（可选）,并开启注解 @EnableAsync

如果不配置，则使用默认的：SimpleAsyncTaskExecutor

package hello;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.context.annotation.Bean;

import org.springframework.scheduling.annotation.EnableAsync;

import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.Executor;

@SpringBootApplication

@EnableAsync

public class Application {

    public static void main(String[] args) {

        // close the application context to shut down the custom ExecutorService

        SpringApplication.run(Application.class, args).close();

    }

    @Bean

    public Executor asyncExecutor() {

        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();

        executor.setCorePoolSize(2);

        executor.setMaxPoolSize(2);

        executor.setQueueCapacity(500);

        executor.setThreadNamePrefix("GithubLookup-");

        executor.initialize();

        return executor;

    }

}

获取并发执行结果

package hello;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.boot.CommandLineRunner;

import org.springframework.stereotype.Component;

import java.util.concurrent.CompletableFuture;

@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

        CompletableFuture<User> page1 = gitHubLookupService.findUser("PivotalSoftware");

        CompletableFuture<User> page2 = gitHubLookupService.findUser("CloudFoundry");

        CompletableFuture<User> page3 = gitHubLookupService.findUser("Spring-Projects");

        // Wait until they are all done

        CompletableFuture.allOf(page1,page2,page3).join();

        // Print results, including elapsed time

        logger.info("Elapsed time: " + (System.currentTimeMillis() - start));

        logger.info("--> " + page1.get());

        logger.info("--> " + page2.get());

        logger.info("--> " + page3.get());

    }

}

结果

2016-09-01 10:25:21.295  INFO 17893 --- [ GithubLookup-2] hello.GitHubLookupService                : Looking up CloudFoundry

2016-09-01 10:25:21.295  INFO 17893 --- [ GithubLookup-1] hello.GitHubLookupService                : Looking up PivotalSoftware

2016-09-01 10:25:23.142  INFO 17893 --- [ GithubLookup-1] hello.GitHubLookupService                : Looking up Spring-Projects

2016-09-01 10:25:24.281  INFO 17893 --- [           main] hello.AppRunner                          : Elapsed time: 2994

2016-09-01 10:25:24.282  INFO 17893 --- [           main] hello.AppRunner                          : --> User [name=Pivotal Software, Inc., blog=http://pivotal.io]

2016-09-01 10:25:24.282  INFO 17893 --- [           main] hello.AppRunner                          : --> User [name=Cloud Foundry, blog=https://www.cloudfoundry.org/]

2016-09-01 10:25:24.282  INFO 17893 --- [           main] hello.AppRunner                          : --> User [name=Spring, blog=http://spring.io/projects]