springboot async 异步多线程
作者:互联网
配置线程池
@Configuration @EnableAsync public class AsyncConfiguration { @Bean("doSomethingExecutor") public Executor doSomethingExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); // 核心线程数:线程池创建时候初始化的线程数 executor.setCorePoolSize(10); // 最大线程数: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(20); // 缓冲队列: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("do-something-"); // 缓冲队列满了之后的拒绝策略:由调用线程处理(一般是主线程) executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy()); executor.initialize(); return executor; } }
@Async注解
@RestController public class AsyncController { @Autowired private AsyncService asyncService; @GetMapping("/open/something") public String something() { int count = 10; for (int i = 0; i < count; i++) { asyncService.doSomething("index = " + i); } return "success"; } } @Slf4j @Service public class AsyncService { // 指定使用beanname为doSomethingExecutor的线程池 @Async("doSomethingExecutor") public String doSomething(String message) { log.info("do something, message={}", message); try { Thread.sleep(1000); } catch (InterruptedException e) { log.error("do something error: ", e); } return message; } }
异步多结果聚合返回 CompletableFuture
@RestController public class AsyncController { @Autowired private AsyncService asyncService; @SneakyThrows @ApiOperation("异步 有返回值") @GetMapping("/open/somethings") public String somethings() { CompletableFuture<String> createOrder = asyncService.doSomething1("create order"); CompletableFuture<String> reduceAccount = asyncService.doSomething2("reduce account"); CompletableFuture<String> saveLog = asyncService.doSomething3("save log"); // 等待所有任务都执行完 CompletableFuture.allOf(createOrder, reduceAccount, saveLog).join(); // 获取每个任务的返回结果 String result = createOrder.get() + reduceAccount.get() + saveLog.get(); return result; } } @Slf4j @Service public class AsyncService { @Async("doSomethingExecutor") public CompletableFuture<String> doSomething1(String message) throws InterruptedException { log.info("do something1: {}", message); Thread.sleep(1000); return CompletableFuture.completedFuture("do something1: " + message); } @Async("doSomethingExecutor") public CompletableFuture<String> doSomething2(String message) throws InterruptedException { log.info("do something2: {}", message); Thread.sleep(1000); return CompletableFuture.completedFuture("; do something2: " + message); } @Async("doSomethingExecutor") public CompletableFuture<String> doSomething3(String message) throws InterruptedException { log.info("do something3: {}", message); Thread.sleep(1000); return CompletableFuture.completedFuture("; do something3: " + message); } }
注意事项
@Async注解会在以下几个场景失效,也就是说明明使用了@Async注解,但就没有走多线程。
- 异步方法使用static关键词修饰;
- 异步类不是一个Spring容器的bean(一般使用注解@Component和@Service,并且能被Spring扫描到);
- SpringBoot应用中没有添加@EnableAsync注解;
- 在同一个类中,一个方法调用另外一个有@Async注解的方法,注解不会生效。原因是@Async注解的方法,是在代理类中执行的。
需要注意的是:
异步方法使用注解@Async的返回值只能为void或者Future及其子类,当返回结果为其他类型时,方法还是会异步执行,但是返回值都是null
标签:CompletableFuture,springboot,do,线程,Async,async,message,多线程,public 来源: https://www.cnblogs.com/wiphombear/p/16433514.html