今天遇到一个需求，在不改动原系统代码的情况下。将Controller的返回值和异常包装到一个统一的返回对象中去。

例如原系统的接口

public String myIp(@ApiIgnore HttpServletRequest request);

返回的只是一个IP字符串"0:0:0:0:0:0:0:1"，目前接口需要包装为：

{"code":200,"message":"","result":"0:0:0:0:0:0:0:1","success":true}

而原异常跳转到error页面，需要调整为

{
  "success": false,
  "message": "For input string: \"fdsafddfs\"",
  "code": 500,
  "result": "message"
}

因此就有了2个工作子项需要完成：

1）Exception的处理

2）controller return值的处理

Exception的自动包装

返回的exception处理可以采用@RestControllerAdvice来处理。

建立自己的Advice类，注入国际化资源（异常需要支持多语言）
 

package org.ccframe.commons.mvc;import lombok.extern.log4j.Log4j2;
import org.apache.commons.lang3.StringUtils;
import org.apache.http.HttpStatus;
import org.ccframe.commons.filter.CcRequestLoggingFilter;
import org.ccframe.commons.util.BusinessException;
import org.ccframe.config.GlobalEx;
import org.ccframe.subsys.core.dto.Result;
import org.springframework.context.MessageSource;
import org.springframework.context.NoSuchMessageException;
import org.springframework.core.MethodParameter;
import org.springframework.http.ResponseEntity;
import org.springframework.orm.ObjectOptimisticLockingFailureException;
import org.springframework.web.HttpRequestMethodNotSupportedException;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
import org.springframework.web.method.support.ModelAndViewContainer;
import org.springframework.web.multipart.MaxUploadSizeExceededException;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.NoHandlerFoundException;import javax.servlet.http.HttpServletRequest;
import java.util.Locale;@RestControllerAdvice
@Log4j2
public class GlobalRestControllerAdvice{private MessageSource messageSource; //国际化资源private LocaleResolver localeResolver;private Object[] EMPTY_ARGS = new Object[0];public GlobalRestControllerAdvice(MessageSource messageSource, LocaleResolver localeResolver){this.messageSource = messageSource;this.localeResolver = localeResolver;}private Result<String> createError(HttpServletRequest request, Exception e,int code, String msgKey, Object[] args){Locale currentLocale = localeResolver.resolveLocale(request);String message = "";try {message = messageSource.getMessage(msgKey, args, currentLocale);}catch (NoSuchMessageException ex){message = e.getMessage();}finally {log.error(message);CcRequestLoggingFilter.pendingLog(); //服务器可以记录出错时的请求啦😂}return Result.error(code, message, msgKey);}@ExceptionHandler(NoHandlerFoundException.class)public Result<?> handlerNoFoundException(HttpServletRequest request, Exception e) {return createError(request, e, HttpStatus.SC_NOT_FOUND, "error.mvc.uriNotFound", EMPTY_ARGS);}@ExceptionHandler(HttpRequestMethodNotSupportedException.class)public Result<?> httpRequestMethodNotSupportedException(HttpServletRequest request, HttpRequestMethodNotSupportedException e){return createError(request,e, HttpStatus.SC_NOT_FOUND,"error.mvc.methodNotSupported",new Object[]{e.getMethod(), StringUtils.join(e.getSupportedMethods(), GlobalEx.DEFAULT_TEXT_SPLIT_CHAR)});}@ExceptionHandler(BusinessException.class)public Result<?> businessException(HttpServletRequest request, BusinessException e){return createError(request,e, HttpStatus.SC_INTERNAL_SERVER_ERROR, e.getMsgKey(), e.getArgs());}@ExceptionHandler(ObjectOptimisticLockingFailureException.class) //乐观锁异常public Result<?> objectOptimisticLockingFailureException(HttpServletRequest request, ObjectOptimisticLockingFailureException e){return createError(request,e, HttpStatus.SC_INTERNAL_SERVER_ERROR, "errors.db.optimisticLock", EMPTY_ARGS);}@ExceptionHandler(MaxUploadSizeExceededException.class) // 文件上传超限，nginx请设置为10Mpublic Result<?> handleMaxUploadSizeExceededException(HttpServletRequest request, MaxUploadSizeExceededException e) {return createError(request, e, HttpStatus.SC_INTERNAL_SERVER_ERROR, "error.mvc.fileTooLarge", EMPTY_ARGS);}@ExceptionHandler(Exception.class)@ResponseBodypublic Result<?> handleException(HttpServletRequest request, Exception e) {log.error(e);return createError(request,e, HttpStatus.SC_INTERNAL_SERVER_ERROR, "message", new Object[]{e.getMessage()});}
}

在Config类初始化该Bean（当然也可以使用@Component支持扫描，随你喜欢）
 

	@Beanpublic GlobalRestControllerAdvice globalRestControllerAdvice(MessageSource messageSource, LocaleResolver localeResolver){return new GlobalRestControllerAdvice(messageSource, localeResolver);}

controller return值的自动包装

网上的例子有很多坑，包括使用HandlerMethodReturnValueHandler，看了源码才发现。还是ResponseBodyAdvice好使。

建立自己的处理Bean

package org.ccframe.commons.mvc;import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.TypeReference;
import org.apache.http.HttpStatus;
import org.ccframe.commons.util.JsonUtil;
import org.ccframe.subsys.core.dto.Result;
import org.springframework.core.MethodParameter;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
import springfox.documentation.swagger.web.ApiResourceController;import java.util.regex.Pattern;@ControllerAdvice
public class CcResponseBodyAdvice implements ResponseBodyAdvice<Object> {private static final Pattern CONTROLLER_PATTERN = Pattern.compile("^org\\.ccframe\\.(subsys|sdk)\\.[a-z0-9]+\\.controller\\.");@Overridepublic boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {return // 只有自己的cotroller类才需要进入，否则swagger都会挂了
CONTROLLER_PATTERN.matcher(returnType.getContainingClass().getName()).find();}@Overridepublic Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {System.out.println(returnType.getContainingClass());Result<Object> result = new Result<>();result.setResult(body);result.setCode(HttpStatus.SC_OK);if(body instanceof String){ //String返回要特殊处理return JSON.toJSONString(result);}else {return result;}}
}

如果你不需要根据正则来指定包，可以直接用RestControllerAdvice的basePackages属性来过滤

注意这里有2个坑

1）String类型的返回被其它的转换接口StringHttpMessageConverter处理，因此返回要进行JSON编码而不能返回其他类型，否则会报cast类型错，因此就有了String部分的特殊处理方法。

2）controller方法签名返回是void时，不会被处理

在Config类初始它：
 

	@Beanpublic CcResponseBodyAdvice ccResponseBodyAdvice() {return new CcResponseBodyAdvice();}

最后。上面两个Bean也可以写在一个，有兴趣的自己尝试。