新增异常类CustomizeInfoException.java：
package com.bolingcavalry.changebody.exception; import lombok.Data; import org.springframework.http.HttpStatus; @Data public class CustomizeInfoException extends Exception { /** * http返回码 */ private HttpStatus httpStatus; /** * body中的code字段(业务返回码) */ private String code; /** * body中的message字段(业务返回信息) */ private String message; }修改RequestBodyRewrite.java的apply方法，这里面是在处理请求body，如果检查到没有user-id字段，就不将请求转发到服务提供方provider-hello，而是返回错误，这里的错误就用CustomizeInfoException类来处理：
@Override public Publisher<String> apply(ServerWebExchange exchange, String body) { try { Map<String, Object> map = objectMapper.readValue(body, Map.class); // 如果请求参数中不含user-id，就返回异常 if (!map.containsKey("user-id")) { CustomizeInfoException customizeInfoException = new CustomizeInfoException(); // 这里返回406，您可以按照业务需要自行调整 customizeInfoException.setHttpStatus(HttpStatus.NOT_ACCEPTABLE); // 这里按照业务需要自行设置code customizeInfoException.setCode("010020003"); // 这里按照业务需要自行设置返回的message customizeInfoException.setMessage("请确保请求参数中的user-id字段是有效的"); return Mono.error(customizeInfoException); } // 取得id int userId = (Integer)map.get("user-id"); // 得到nanme后写入map map.put("user-name", mockUserName(userId)); return Mono.just(objectMapper.writeValueAsString(map)); } catch (Exception ex) { log.error("1. json process fail", ex); return Mono.error(new Exception("1. json process fail", ex)); } }异常处理类MyErrorWebExceptionHandler.java，这里有一处需要重点关注的是：下面的代码仅是参考而已，您无需拘泥于CustomizeInfoException有关的逻辑，完全能按照业务需求自由设置返回的状态码和body：
package com.bolingcavalry.changebody.handler; import com.bolingcavalry.changebody.exception.CustomizeInfoException; import org.springframework.boot.autoconfigure.web.ErrorProperties; import org.springframework.boot.autoconfigure.web.WebProperties; 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.MediaType; import org.springframework.web.reactive.function.BodyInserters; import org.springframework.web.reactive.function.server.ServerRequest; import org.springframework.web.reactive.function.server.ServerResponse; import reactor.core.publisher.Mono; import java.util.HashMap; import java.util.Map; public class MyErrorWebExceptionHandler extends DefaultErrorWebExceptionHandler { public MyErrorWebExceptionHandler(ErrorAttributes errorAttributes, WebProperties.Resources resources, ErrorProperties errorProperties, ApplicationContext applicationContext) { super(errorAttributes, resources, errorProperties, applicationContext); } @Override protected Mono<ServerResponse> renderErrorResponse(ServerRequest request) { // 返回码 int status; // 最终是用responseBodyMap来生成响应body的 Map<String, Object> responseBodyMap = new HashMap<>(); // 这里和父类的做法一样，取得DefaultErrorAttributes整理出来的所有异常信息 Map<String, Object> error = getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.ALL)); // 原始的异常信息可以用getError方法取得 Throwable throwable = getError(request); // 如果异常类是咱们定制的，就定制 if (throwable instanceof CustomizeInfoException) { CustomizeInfoException myGatewayException = (CustomizeInfoException) throwable; // http返回码、body的code字段、body的message字段，这三个信息都从CustomizeInfoException实例中获取 status = myGatewayException.getHttpStatus().value(); responseBodyMap.put("code", myGatewayException.getCode()); responseBodyMap.put("message", myGatewayException.getMessage()); responseBodyMap.put("data", null); } else { // 如果不是咱们定制的异常，就维持和父类一样的逻辑 // 返回码 status = getHttpStatus(error); // body内容 responseBodyMap.putAll(error); } return ServerResponse // http返回码 .status(status) // 类型和以前一样 .contentType(MediaType.APPLICATION_JSON) // 响应body的内容 .body(BodyInserters.fromValue(responseBodyMap)); } }最后是配置类MyErrorWebFluxAutoConfiguration.java：
package com.bolingcavalry.changebody.config; import com.bolingcavalry.changebody.handler.MyErrorWebExceptionHandler; import org.springframework.beans.factory.ObjectProvider; import org.springframework.boot.autoconfigure.AutoConfigureBefore; import org.springframework.boot.autoconfigure.condition.ConditionalOnClass; import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication; import org.springframework.boot.autoconfigure.web.ServerProperties; import org.springframework.boot.autoconfigure.web.WebProperties; import org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration; 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.annotation.Order; import org.springframework.http.codec.ServerCodecConfigurer; import org.springframework.web.reactive.config.WebFluxConfigurer; import org.springframework.web.reactive.result.view.ViewResolver; import java.util.stream.Collectors; @Configuration(proxyBeanMethods = false) @AutoConfigureBefore(WebFluxAutoConfiguration.class) public class MyErrorWebFluxAutoConfiguration { private final ServerProperties serverProperties; public MyErrorWebFluxAutoConfiguration(ServerProperties serverProperties) { this.serverProperties = serverProperties; } @Bean @Order(-1) public ErrorWebExceptionHandler errorWebExceptionHandler(ErrorAttributes errorAttributes, org.springframework.boot.autoconfigure.web.ResourceProperties resourceProperties, WebProperties webProperties, ObjectProvider<ViewResolver> viewResolvers, ServerCodecConfigurer serverCodecConfigurer, ApplicationContext applicationContext) { MyErrorWebExceptionHandler exceptionHandler = new MyErrorWebExceptionHandler(errorAttributes, resourceProperties.hasBeenCustomized() ? resourceProperties : webProperties.getResources(), this.serverProperties.getError(), applicationContext); exceptionHandler.setViewResolvers(viewResolvers.orderedStream().collect(Collectors.toList())); exceptionHandler.setMessageWriters(serverCodecConfigurer.getWriters()); exceptionHandler.setMessageReaders(serverCodecConfigurer.getReaders()); return exceptionHandler; } }编码完成，该把程序运行起来验证效果了；
验证
启动应用gateway-change-body