spring 5 webflux异常处理-白红宇

序

本文主要研究一下spring 5 webflux的异常处理

maven


    			
     
      org.springframework.boot
     			
     
      spring-boot-starter-webflux
     		
    复制代码

ExceptionHandler

由于webflux也支持传统spring mvc的大部分注解，因此原来的ExceptionHandler也是支持的。

@RestControllerAdvicepublic class ExceptionHandlers {    private static final Logger LOGGER = LoggerFactory.getLogger(ExceptionHandlers.class);    @ExceptionHandler(Exception.class)    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)    public String serverExceptionHandler(Exception ex) {        LOGGER.error(ex.getMessage(),ex);        return ex.getMessage();    }}复制代码

启动的时候可以看到日志

2018-02-12 19:26:03.249  INFO 7053 --- [           main] o.s.w.r.r.m.a.ControllerMethodResolver   : Looking for @ControllerAdvice: org.springframework.boot.web.reactive.context.AnnotationConfigReactiveWebServerApplicationContext@65d09a04: startup date [Mon Feb 12 19:25:59 CST 2018]; root of context hierarchy2018-02-12 19:26:03.281  INFO 7053 --- [           main] o.s.w.r.r.m.a.ControllerMethodResolver   : Detected @ExceptionHandler methods in exceptionHandlers复制代码

spring-webflux-5.0.2.RELEASE-sources.jar!/org/springframework/web/reactive/result/method/annotation/ControllerMethodResolver.java

/** * Package-private class to assist {@link RequestMappingHandlerAdapter} with * resolving, initializing, and caching annotated methods declared in * {@code @Controller} and {@code @ControllerAdvice} components: * 
    
      * 
     {@code @InitBinder} * 
     {@code @ModelAttribute} * 
     {@code @RequestMapping} * 
     {@code @ExceptionHandler} * 
    
 * * @author Rossen Stoyanchev * @since 5.0 */class ControllerMethodResolver {	private static Log logger = LogFactory.getLog(ControllerMethodResolver.class);	private final List
    
      initBinderResolvers;	private final List
     
       modelAttributeResolvers;	private final List
      
        requestMappingResolvers;	private final List
       
         exceptionHandlerResolvers;	private final ReactiveAdapterRegistry reactiveAdapterRegistry;    //......}复制代码

可以看到支持InitBinder，ModelAttribute，RequestMapping，ExceptionHandler这几个注解。

实例

@GetMapping(value = "/error",produces = MediaType.APPLICATION_JSON_UTF8_VALUE)    public Mono
    
      exceptionReturn(){//        throw new RuntimeException("hello");        return Mono.error(new RuntimeException("test error"));    }复制代码

与传统mvc不同的是，除了直接throw异常外，Mono或Flux可以直接error一个异常，在exceptionHandlers都可以被接收处理

小结

webflux支持mvc的注解，是一个非常便利的功能，相比较于RouteFunction，自动扫描注册比较省事。异常处理可以沿用ExceptionHandler。