Spring Cloud Gateway的全局异常处理

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Spring Cloud Gateway中的全局异常处理不能直接用@ControllerAdvice来处理,通过跟踪异常信息的抛出,找到对应的源码,自定义一些处理逻辑来符合业务的需求。

网关都是给接口做代理转发的,后端对应的都是REST API,返回数据格式都是JSON。如果不做处理,当发生异常时,Gateway默认给出的错误信息是页面,不方便前端进行异常处理。

需要对异常信息进行处理,返回JSON格式的数据给客户端。下面先看实现的代码,后面再跟大家讲下需要注意的地方。

自定义异常处理逻辑:

    package com.cxytiandi.gateway.exception;

    import java.util.HashMap;
    import java.util.Map;

    import org.springframework.boot.autoconfigure.web.ErrorProperties;
    import org.springframework.boot.autoconfigure.web.ResourceProperties;
    import org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler;
    import org.springframework.boot.web.reactive.error.ErrorAttributes;
    import org.springframework.context.ApplicationContext;
    import org.springframework.http.HttpStatus;
    import org.springframework.web.reactive.function.server.RequestPredicates;
    import org.springframework.web.reactive.function.server.RouterFunction;
    import org.springframework.web.reactive.function.server.RouterFunctions;
    import org.springframework.web.reactive.function.server.ServerRequest;
    import org.springframework.web.reactive.function.server.ServerResponse;

    /**
     * 自定义异常处理
     * 
     * <p>异常时用JSON代替HTML异常信息<p>
     * 
     * @author yinjihuan
     *
     */
    public class JsonExceptionHandler extends DefaultErrorWebExceptionHandler {

        public JsonExceptionHandler(ErrorAttributes errorAttributes, ResourceProperties resourceProperties,
                ErrorProperties errorProperties, ApplicationContext applicationContext) {
            super(errorAttributes, resourceProperties, errorProperties, applicationContext);
        }

        /**
         * 获取异常属性
         */
        @Override
        protected Map<String, Object> getErrorAttributes(ServerRequest request, boolean includeStackTrace) {
            int code = 500;
            Throwable error = super.getError(request);
            if (error instanceof org.springframework.cloud.gateway.support.NotFoundException) {
                code = 404;
            }
            return response(code, this.buildMessage(request, error));
        }

        /**
         * 指定响应处理方法为JSON处理的方法
         * @param errorAttributes
         */
        @Override
        protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
            return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);
        }

        /**
         * 根据code获取对应的HttpStatus
         * @param errorAttributes
         */
        @Override
        protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) {
            int statusCode = (int) errorAttributes.get("code");
            return HttpStatus.valueOf(statusCode);
        }

        /**
         * 构建异常信息
         * @param request
         * @param ex
         * @return
         */
        private String buildMessage(ServerRequest request, Throwable ex) {
            StringBuilder message = new StringBuilder("Failed to handle request [");
            message.append(request.methodName());
            message.append(" ");
            message.append(request.uri());
            message.append("]");
            if (ex != null) {
                message.append(": ");
                message.append(ex.getMessage());
            }
            return message.toString();
        }

        /**
         * 构建返回的JSON数据格式
         * @param status        状态码
         * @param errorMessage  异常信息
         * @return
         */
        public static Map<String, Object> response(int status, String errorMessage) {
            Map<String, Object> map = new HashMap<>();
            map.put("code", status);
            map.put("message", errorMessage);
            map.put("data", null);
            return map;
        }

    }

覆盖默认的配置:

    package com.cxytiandi.gateway.exception;

    import java.util.Collections;
    import java.util.List;

    import org.springframework.beans.factory.ObjectProvider;
    import org.springframework.boot.autoconfigure.web.ResourceProperties;
    import org.springframework.boot.autoconfigure.web.ServerProperties;
    import org.springframework.boot.context.properties.EnableConfigurationProperties;
    import org.springframework.boot.web.reactive.error.ErrorAttributes;
    import org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.core.Ordered;
    import org.springframework.core.annotation.Order;
    import org.springframework.http.codec.ServerCodecConfigurer;
    import org.springframework.web.reactive.result.view.ViewResolver;

    /**
     * 覆盖默认的异常处理
     * 
     * @author yinjihuan
     *
     */
    @Configuration
    @EnableConfigurationProperties({ServerProperties.class, ResourceProperties.class})
    public class ErrorHandlerConfiguration {

        private final ServerProperties serverProperties;

        private final ApplicationContext applicationContext;

        private final ResourceProperties resourceProperties;

        private final List<ViewResolver> viewResolvers;

        private final ServerCodecConfigurer serverCodecConfigurer;

        public ErrorHandlerConfiguration(ServerProperties serverProperties,
                                         ResourceProperties resourceProperties,
                                         ObjectProvider<List<ViewResolver>> viewResolversProvider,
                                         ServerCodecConfigurer serverCodecConfigurer,
                                         ApplicationContext applicationContext) {
            this.serverProperties = serverProperties;
            this.applicationContext = applicationContext;
            this.resourceProperties = resourceProperties;
            this.viewResolvers = viewResolversProvider.getIfAvailable(Collections::emptyList);
            this.serverCodecConfigurer = serverCodecConfigurer;
        }

        @Bean
        @Order(Ordered.HIGHEST_PRECEDENCE)
        public ErrorWebExceptionHandler errorWebExceptionHandler(ErrorAttributes errorAttributes) {
            JsonExceptionHandler exceptionHandler = new JsonExceptionHandler(
                    errorAttributes, 
                    this.resourceProperties,
                    this.serverProperties.getError(), 
                    this.applicationContext);
            exceptionHandler.setViewResolvers(this.viewResolvers);
            exceptionHandler.setMessageWriters(this.serverCodecConfigurer.getWriters());
            exceptionHandler.setMessageReaders(this.serverCodecConfigurer.getReaders());
            return exceptionHandler;
        }

    }

注意点

  • 异常时如何返回JSON而不是HTML?

在org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler中的getRoutingFunction()方法就是控制返回格式的,原代码如下:

    @Override
    protected RouterFunction<ServerResponse> getRoutingFunction(
                ErrorAttributes errorAttributes) {
           return RouterFunctions.route(acceptsTextHtml(), this::renderErrorView)
                    .andRoute(RequestPredicates.all(), this::renderErrorResponse);
    }

这边优先是用HTML来显示的,想用JSON的改下就可以了,如下:

    protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
           return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);
    }
  • getHttpStatus需要重写

原始的方法是通过status来获取对应的HttpStatus的,代码如下:

    protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) {
          int statusCode = (int) errorAttributes.get("status");
          return HttpStatus.valueOf(statusCode);
    }

如果我们定义的格式中没有status字段的话,这么就会报错,找不到对应的响应码,要么返回数据格式中增加status子段,要么重写,我这边返回的是code,所以要重写,代码如下:

    @Override
    protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) {
        int statusCode = (int) errorAttributes.get("code");
        return HttpStatus.valueOf(statusCode);
    }

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来源:http://ddrv.cn/a/88268

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