0424 springboot多线程

Myth丶恋晨 2024-03-23 17:08 64阅读 0赞

### 简单说明如何在springboot中使用多线程？ ###

1.  写一个配置类并带上@EnableAsync注解，如

@Configuration
    @EnableAsync  // 启用异步任务
    public class AsyncConfiguration {
        
    
        // 声明一个线程池(并指定线程池的名字)
        @Bean("taskExecutor")
        public Executor asyncExecutor() {
        
            ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
            //核心线程数5：线程池创建时候初始化的线程数
            executor.setCorePoolSize(5);
            //最大线程数5：线程池最大的线程数，只有在缓冲队列满了之后才会申请超过核心线程数的线程
            executor.setMaxPoolSize(5);
            //缓冲队列500：用来缓冲执行任务的队列
            executor.setQueueCapacity(500);
            //允许线程的空闲时间60秒：当超过了核心线程出之外的线程在空闲时间到达之后会被销毁
            executor.setKeepAliveSeconds(60);
            //线程池名的前缀：设置好了之后可以方便我们定位处理任务所在的线程池
            executor.setThreadNamePrefix("DailyAsync-");
            executor.initialize();
            return executor;
        }
    }

1.  使用线程池，在需要多线程运行的方法上加@Async(“taskExecutor”)

Service
    public class GitHubLookupService {
        
    
        private static final Logger logger = LoggerFactory.getLogger(GitHubLookupService.class);
    
        @Autowired
        private RestTemplate restTemplate;
    
        // 这里进行标注为异步任务，在执行此方法的时候，会单独开启线程来执行(并指定线程池的名字)
        // @Async表示它将在一个单独的线程上运行。
        // 该方法的返回类型是 CompletableFuture 而不是 String，这是任何异步服务的要求。
        @Async("taskExecutor")
        public CompletableFuture<String> findUser(String user) throws InterruptedException {
        
            logger.info("Looking up " + user);
            String url = String.format("https://api.github.com/users/%s", user);
            String results = restTemplate.getForObject(url, String.class);
            // Artificial delay of 3s for demonstration purposes
            Thread.sleep(3000L);
            return CompletableFuture.completedFuture(results);
        }
    }

1.  单元测试

@RunWith(SpringRunner.class)
    @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)
    public class AsyncTests {
        
        private static final Logger logger = LoggerFactory.getLogger(AsyncTests.class);
    
        @Autowired
        private GitHubLookupService gitHubLookupService;
    
        @Test
        public void asyncTest() throws InterruptedException, ExecutionException {
        
            // Start the clock
            long start = System.currentTimeMillis();
    
            // Kick of multiple, asynchronous lookups
            CompletableFuture<String> page1 = gitHubLookupService.findUser("PivotalSoftware");
            CompletableFuture<String> page2 = gitHubLookupService.findUser("CloudFoundry");
            CompletableFuture<String> page3 = gitHubLookupService.findUser("Spring-Projects");
    
            // Wait until they are all done
            //join() 的作用：让“主线程”等待“子线程”结束之后才能继续运行
            CompletableFuture.allOf(page1,page2,page3).join();
    
            // Print results, including elapsed time
            float exc = (float)(System.currentTimeMillis() - start)/1000;
            logger.info("Elapsed time: " + exc + " seconds");
            logger.info("--> " + page1.get());
            logger.info("--> " + page2.get());
            logger.info("--> " + page3.get());
        }
    
    }