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Spring Cloud Gateway 全局异常处理

发表于 2019-11-12 更新于 2021-03-09 分类于 Spring Cloud 阅读次数： Valine：
本文字数： 6.8k 阅读时长 ≈ 6 分钟

Spring Cloud Gateway中的全局异常处理不能直接用@ControllerAdvice来处理，所以需要自定义异常处理

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。Spring Cloud Gateway 中的全局异常处理不能直接用 @ControllerAdvice 来处理，需要自定义异常处理。

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;
    }

}

覆盖默认的异常处理

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;
    }

}

注意项

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：

1
2
3

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);
}

原文链接

 yinjihuan：Spring Cloud Gateway 的全局异常处理