springmvc全局異常處理ControllerAdvice區分返回響應類型是頁面還是JSON

思路：

加一個攔截器，在preHandler中取得HandlerMethod，判斷其方法的返回類型，以及方法的注解和類的注解。

如果返回是json，收到異常則返回默認的異常包裝類型。

如果返回是頁面，收到異常則返回默認的異常頁面。

 攔截器代碼如下:

package com.xxx.config;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import java.lang.reflect.Method;

@Component
public class BaseInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (!(handler instanceof HandlerMethod)) {
            return true;
        }

        HandlerMethod hm = (HandlerMethod) handler;
        Method method = hm.getMethod();

        boolean isPage = method.getReturnType().equals(String.class);
        boolean isJosn = method.isAnnotationPresent(ResponseBody.class);
        boolean isController = (!hm.getBeanType().isAnnotationPresent(RestController.class) && hm.getBeanType().isAnnotationPresent(Controller.class));
        
        //controller_response_is_view 這個表示controller的返回響應類型是頁面
        request.setAttribute("method_return_is_view", isPage && !isJosn && isController);

        return true;
    }

}

 全局異常處理ControllerAdvice代碼如下：

package com.xxx.config;

import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.view.json.MappingJackson2JsonView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@ControllerAdvice
@Slf4j
public class CommonExceptionHandler {

    @ExceptionHandler
    public ModelAndView handleException(Exception exception, HttpServletRequest request, HttpServletResponse response) throws Exception{
        log.error(exception.getMessage(), exception);

        Object o = request.getAttribute("controller_response_is_view");
        if( o == null) {
            throw exception;
        }

        boolean isView = (Boolean)o;
        if(isView){  //返回頁面
            //獲取http狀態碼statusCode:401,404.jsp,500
            Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
            if(statusCode == 401){
                return new ModelAndView("error/401");
            }else if(statusCode == 403){
                return new ModelAndView("error/403");
            }else if(statusCode == 404){
                return new ModelAndView("error/404");
            }else{
                return new ModelAndView("error/500");
            }
        }

        //返回json
        ModelAndView mv = new ModelAndView(new MappingJackson2JsonView());
        mv.addObject("code","500");
        mv.addObject("message",exception.getMessage());
        return mv;
    }

}