springboot async异步处理方案

时间:2022-11-27 08:53:52

springboot提供了两种异步处理方案,一是传统同步web处理加异步service层,二是异步web处理框架webFlux。

一、传统同步web处理加异步service层

使用流程:在springboot application启动类上添加@EnableAsync注解。在service层类或方法上添加@Async注解,同时在异步方法所在的service层类上添加@Component或@service 等注解,该方法必须返回AsyncResult或CompletableFuture、ListenableFuture、Future之一,然后controller层通过@Autowired自动注入service类并使用异步类。

controller和service层代码如下:

@RestController
public class UserCtroller {

    @Autowired
    UserService userService;

    @RequestMapping( "/n/{name}")
    @ResponseBody
    public User getUserByName(@PathVariable String name){
        AsyncResult<Optional<User>> user = userService.getUserByName( name );
        try{
            return user.get().isEmpty() ? null: user.get().get() ;
        } catch (ExecutionException e) {
            return null;
        }
    }

    @RequestMapping( "/l")
    @ResponseBody
    public List<User> getAll(){
        return userService.getAll();
    }

}
@Service
public class UserServiceImpl implements UserService {

    List<User> users = Arrays.asList(
            new User( "a", 20 , "aaaa"),
            new User( "b", 20 , "aaaa"),
            new User( "c", 20 , "aaaa")
    );

    @Override
    @Async
    public AsyncResult<Optional<User>> getUserByName(String name){
        Optional<User> user = users.stream().filter( (u) ->  Objects.equals( u.getName(), name ) ).findFirst();
        return new AsyncResult<>( user );
    }

    @Override
    @Async
    public List<User> getAll(){
        return  users;
    }
}

在service的 getUserByName方法内置断点,执行监控调用堆栈,结果如下。可以看出spring采用AOP的方式将@Async的注解的方法封装为异步执行。

getUserByName:26, UserServiceImpl (com.alun.serviceasync)
invoke0:-1, NativeMethodAccessorImpl (jdk.internal.reflect)
invoke:77, NativeMethodAccessorImpl (jdk.internal.reflect)
invoke:43, DelegatingMethodAccessorImpl (jdk.internal.reflect)
invoke:568, Method (java.lang.reflect)
invokeJoinpointUsingReflection:344, AopUtils (org.springframework.aop.support)
invokeJoinpoint:198, ReflectiveMethodInvocation (org.springframework.aop.framework)
proceed:163, ReflectiveMethodInvocation (org.springframework.aop.framework)
lambda$invoke$0:115, AsyncExecutionInterceptor (org.springframework.aop.interceptor)
call:-1, AsyncExecutionInterceptor$$Lambda$778/0x0000000800fb3710 (org.springframework.aop.interceptor)
run$$$capture:264, FutureTask (java.util.concurrent)
run:-1, FutureTask (java.util.concurrent)
 - 异步堆栈跟踪
<init>:132, FutureTask (java.util.concurrent)
<init>:44, ListenableFutureTask (org.springframework.util.concurrent)
submitListenable:412, ThreadPoolTaskExecutor (org.springframework.scheduling.concurrent)
doSubmit:286, AsyncExecutionAspectSupport (org.springframework.aop.interceptor)
invoke:129, AsyncExecutionInterceptor (org.springframework.aop.interceptor)
proceed:186, ReflectiveMethodInvocation (org.springframework.aop.framework)
invoke:215, JdkDynamicAopProxy (org.springframework.aop.framework)
getUserByName:-1, $Proxy50 (jdk.proxy2)
getUserByName:27, UserCtroller (com.alun.serviceasync)

使用数据库事务时一定要注意:在Async方法上标注@Transactional,事务无效。 在Async方法调用的方法上标注@Transactional 有效。

Springboot中使用@Async实现异步处理及注意事项  这篇文章总结的不错,值得大家参考。

二、异步web处理框架webFlux

spring5提供了webFlux异步处理框架,提高系统吞吐量和伸缩性,以 Reactor为核心,基于Servlet3.1规范实现,即从servlet线程就以异步方式处理请求。springboot提供了TomcatReactiveWebServerFactory、NettyReactiveWebServerFactory、UndertowReactiveWebServerFactory、JettyReactiveWebServerFactory四种ReactiveWebServer实现。默认使用容器是 Netty,Netty 是高性能的 NIO 框架。

controller层的方法需要返回Mono或Flux,service代码不需要改动。如:

@RestController
public class UserCtroller {

    @Autowired
    UserService userService;

    @RequestMapping( "/n/{name}")
    public Mono<User> getUserByName( @PathVariable String name){
        return userService.getUserByName( name );
    }

    @RequestMapping( "/l")
    public Flux<User> getAll(){
        return userService.getAll();
    }
}

SpringWebflux 提供两种编程模式:注解编程模型和函数式编程模型。

函数式编程模型参见Spring Webflux

两种方式的gradle文件的配置如下,如需切换server提供方式,可以如下修改:

web mvc方式配置:

    // web
	implementation ('org.springframework.boot:spring-boot-starter-web'){
		exclude  group:'org.springframework.boot', module:'spring-boot-starter-tomcat'
	}
    implementation 'org.springframework.boot:spring-boot-starter-undertow'

webFlux方式的配置:

// webflux
	implementation ('org.springframework.boot:spring-boot-starter-webflux'){
		exclude group:'org.springframework.boot', module:'spring-boot-starter-netty'
	}
	implementation 'org.springframework.boot:spring-boot-starter-undertow'