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本篇內(nèi)容主要講解“在SpringBoot怎么優(yōu)雅的使用多線程”,感興趣的朋友不妨來看看。本文介紹的方法操作簡單快捷,實(shí)用性強(qiáng)。下面就讓小編來帶大家學(xué)習(xí)“在SpringBoot怎么優(yōu)雅的使用多線程”吧!
SpringBoot應(yīng)用中需要添加@EnableAsync注解,來開啟異步調(diào)用,一般還會(huì)配置一個(gè)線程池,異步的方法交給特定的線程池完成,如下:
@Configuration @EnableAsync public class AsyncConfiguration { @Bean("doSomethingExecutor") public Executor doSomethingExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); // 核心線程數(shù):線程池創(chuàng)建時(shí)候初始化的線程數(shù) executor.setCorePoolSize(10); // 最大線程數(shù):線程池最大的線程數(shù),只有在緩沖隊(duì)列滿了之后才會(huì)申請(qǐng)超過核心線程數(shù)的線程 executor.setMaxPoolSize(20); // 緩沖隊(duì)列:用來緩沖執(zhí)行任務(wù)的隊(duì)列 executor.setQueueCapacity(500); // 允許線程的空閑時(shí)間60秒:當(dāng)超過了核心線程之外的線程在空閑時(shí)間到達(dá)之后會(huì)被銷毀 executor.setKeepAliveSeconds(60); // 線程池名的前綴:設(shè)置好了之后可以方便我們定位處理任務(wù)所在的線程池 executor.setThreadNamePrefix("do-something-"); // 緩沖隊(duì)列滿了之后的拒絕策略:由調(diào)用線程處理(一般是主線程) executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy()); executor.initialize(); return executor; } }
使用的方式非常簡單,在需要異步的方法上加@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為doSomethingExecutor的線程池 @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; } }
訪問:127.0.0.1:8080/open/something,日志如下
2023-02-06 23:42:42.486 INFO 21168 --- [io-8200-exec-17] x.g.b.system.controller.AsyncController : do something end, time 8 milliseconds
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-1] x.gits.boot.system.service.AsyncService : do something, message=index = 0
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-5] x.gits.boot.system.service.AsyncService : do something, message=index = 4
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-4] x.gits.boot.system.service.AsyncService : do something, message=index = 3
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-6] x.gits.boot.system.service.AsyncService : do something, message=index = 5
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-9] x.gits.boot.system.service.AsyncService : do something, message=index = 8
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-8] x.gits.boot.system.service.AsyncService : do something, message=index = 7
2023-02-06 23:42:42.488 INFO 21168 --- [do-something-10] x.gits.boot.system.service.AsyncService : do something, message=index = 9
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-7] x.gits.boot.system.service.AsyncService : do something, message=index = 6
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-2] x.gits.boot.system.service.AsyncService : do something, message=index = 1
2023-02-06 23:42:42.488 INFO 21168 --- [ do-something-3] x.gits.boot.system.service.AsyncService : do something, message=index = 2
由此可見已經(jīng)達(dá)到異步執(zhí)行的效果了,并且使用到了咱們配置的線程池。
當(dāng)異步方法有返回值時(shí),如何獲取異步方法執(zhí)行的返回結(jié)果呢?這時(shí)需要異步調(diào)用的方法帶有返回值CompletableFuture。
CompletableFuture是對(duì)Feature的增強(qiáng),F(xiàn)eature只能處理簡單的異步任務(wù),而CompletableFuture可以將多個(gè)異步任務(wù)進(jìn)行復(fù)雜的組合。如下:
@RestController public class AsyncController { @Autowired private AsyncService asyncService; @SneakyThrows @ApiOperation("異步 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"); // 等待所有任務(wù)都執(zhí)行完 CompletableFuture.allOf(createOrder, reduceAccount, saveLog).join(); // 獲取每個(gè)任務(wù)的返回結(jié)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); } }
訪問接口
C:\Users\Administrator>curl -X GET "http://localhost:8080/open/something" -H "accept: */*"
do something1: create order;
do something2: reduce account;
do something3: save log
控制臺(tái)上關(guān)鍵日志如下:
2023-02-06 00:27:42.238 INFO 5672 --- [ do-something-3] x.gits.boot.system.service.AsyncService : do something3: save log
2023-02-06 00:27:42.238 INFO 5672 --- [ do-something-2] x.gits.boot.system.service.AsyncService : do something2: reduce account
2023-02-06 00:27:42.238 INFO 5672 --- [ do-something-1] x.gits.boot.system.service.AsyncService : do something1: create order
@Async注解會(huì)在以下幾個(gè)場(chǎng)景失效,也就是說明明使用了@Async注解,但就沒有走多線程。
異步方法使用static關(guān)鍵詞修飾;
異步類不是一個(gè)Spring容器的bean(一般使用注解@Component和@Service,并且能被Spring掃描到);
SpringBoot應(yīng)用中沒有添加@EnableAsync注解;
在同一個(gè)類中,一個(gè)方法調(diào)用另外一個(gè)有@Async注解的方法,注解不會(huì)生效。原因是@Async注解的方法,是在代理類中執(zhí)行的。
需要注意的是: 異步方法使用注解@Async的返回值只能為void或者Future及其子類,當(dāng)返回結(jié)果為其他類型時(shí),方法還是會(huì)異步執(zhí)行,但是返回值都是null,部分源碼如下:
AsyncExecutionInterceptor#invoke
通過上邊幾個(gè)示例,@Async實(shí)際還是通過Future或CompletableFuture來異步執(zhí)行的,Spring又封裝了一下,讓我們使用的更方便。
到此,相信大家對(duì)“在SpringBoot怎么優(yōu)雅的使用多線程”有了更深的了解,不妨來實(shí)際操作一番吧!這里是億速云網(wǎng)站,更多相關(guān)內(nèi)容可以進(jìn)入相關(guān)頻道進(jìn)行查詢,關(guān)注我們,繼續(xù)學(xué)習(xí)!
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