• SpringMVC 04(JSON和全局异常处理)

    目录

    一，SpringMVC对JSON的支持            

    二，SpringMVC 的全局异常处理

    一，SpringMVC对JSON的支持     

    pom.xml依赖

    1.  <dependency>
    2.       <groupId>com.fasterxml.jackson.coregroupId>
    3.       <artifactId>jackson-databindartifactId>
    4.       <version>2.9.3version>
    5.     dependency>
    6.     <dependency>
    7.       <groupId>com.fasterxml.jackson.coregroupId>
    8.       <artifactId>jackson-coreartifactId>
    9.       <version>2.9.3version>
    10.     dependency>
    11.     <dependency>
    12.       <groupId>com.fasterxml.jackson.coregroupId>
    13.       <artifactId>jackson-annotationsartifactId>
    14.       <version>2.9.3version>
    15.     dependency>

       Springmvc.xml配置

    1. <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
    2.         <property name="messageConverters">
    3.             <list>
    4.                 <ref bean="mappingJackson2HttpMessageConverter"/>
    5.             list>
    6.         property>
    7.     bean>
    8.     <bean id="mappingJackson2HttpMessageConverter"
    9.           class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
    10.         
    11.         <property name="supportedMediaTypes">
    12.             <list>
    13.                 <value>text/html;charset=UTF-8value>
    14.                 <value>text/json;charset=UTF-8value>
    15.                 <value>application/json;charset=UTF-8value>
    16.             list>
    17.         property>
    18.     bean>

    后台代码：

    1. package com.ruojuan.ssm.web;
    2.  
    3. import com.ruojuan.ssm.Exception.GlobalException;
    4. import com.ruojuan.ssm.biz.ClazzBiz;
    5. import com.ruojuan.ssm.model.Clazz;
    6. import com.ruojuan.ssm.util.PageBean;
    7. import org.springframework.beans.factory.annotation.Autowired;
    8. import org.springframework.stereotype.Controller;
    9. import org.springframework.web.bind.annotation.RequestMapping;
    10. import org.springframework.web.bind.annotation.ResponseBody;
    11.  
    12. import javax.servlet.http.HttpServletRequest;
    13. import java.util.HashMap;
    14. import java.util.List;
    15. import java.util.Map;
    16.  
    17. /**
    18.  * @author ruojuan
    19.  * @site 123456999
    20.  * @company 玉渊工作室
    21.  * @create 2022-08-22 16:25
    22.  */
    23. @ResponseBody
    24. @Controller
    25. @RequestMapping("/clz/json")
    26. public class JsonController {
    27.  
    28.     @Autowired
    29.     private ClazzBiz clazzBiz;
    30.  
    31.     /**
    32.      * 返回List
    33.      * @param req
    34.      * @param clazz
    35.      * @return
    36.      */
    37.     @RequestMapping("/list")
    38.     public List list(HttpServletRequest req, Clazz clazz){
    39.         PageBean pageBean = new PageBean();
    40.         pageBean.setRequest(req);
    41.         if(true) {
    42.             throw new RuntimeException("查询班级信息异常，异常存在于JsonController.list方法");
    43.         }
    44.         List lst = this.clazzBiz.listPager(clazz, pageBean);
    45.         return lst;
    46.     }
    47.  
    48.     /**
    49.      * 返回T
    50.      * @param req
    51.      * @param clazz
    52.      * @return
    53.      */
    54.     /*@RequestMapping("/load")
    55.     public Clazz load(HttpServletRequest req, Clazz clazz){
    56.         PageBean pageBean = new PageBean();
    57.         pageBean.setRequest(req);
    58.         if(true){
    59.           throw new GlobalException("系统繁忙，请参考E007;");
    60.         }
    61.         return this.clazzBiz.listPager(clazz,pageBean).get(0);
    62.     }*/
    63.     @RequestMapping("/load")
    64.     public Clazz load(HttpServletRequest req, Clazz clazz){
    65.         if(clazz.getCid() != null){
    66.             List lst = this.clazzBiz.listPager(clazz, null);
    67.             if (true)
    68.                 throw new GlobalException("错误出现在 JsonController.load...");
    69.             return lst.get(0);
    70.         }
    71.         return null;
    72.     }
    73.  
    74.  
    75.     /**
    76.      * 返回List
    77.      * @param req
    78.      * @param clazz
    79.      * @return
    80.      */
    81.     @RequestMapping("/mapList")
    82.     public List mapList(HttpServletRequest req, Clazz clazz){
    83.         PageBean pageBean = new PageBean();
    84.         pageBean.setRequest(req);
    85.         List lst = this.clazzBiz.listMapPager(clazz, pageBean);
    86.         return lst;
    87.     }
    88.  
    89.     /**
    90.      * 返回Map
    91.      * @param req
    92.      * @param clazz
    93.      * @return
    94.      */
    95.     @RequestMapping("/mapLoad")
    96.     public Map mapLoad(HttpServletRequest req, Clazz clazz){
    97.         if(clazz.getCid() != null){
    98.             List lst = this.clazzBiz.listMapPager(clazz, null);
    99.             return lst.get(0);
    100.         }
    101.         return null;
    102.     }
    103.  
    104.  
    105.     @RequestMapping("/all")
    106.     public Map all(HttpServletRequest req, Clazz clazz){
    107.         PageBean pageBean = new PageBean();
    108.         pageBean.setRequest(req);
    109.         List lst = this.clazzBiz.listPager(clazz, pageBean);
    110.         Map map = new HashMap();
    111.         map.put("lst",lst);
    112.         map.put("pageBean",pageBean);
    113.         return map;
    114.     }
    115.  
    116.     @RequestMapping("/jsonStr")
    117.     public String jsonStr(HttpServletRequest req, Clazz clazz){
    118.         return "Edit";
    119.     }
    120.  
    121.  
    122. }

    servic层 ：

    1. public List mapListPager(Clazz clazz,PageBean pageBean) {
    2.         return clazzMapper.mapListPager(clazz);
    3.     }

     Mapper.xml

    1. <select id="mapListPager" parameterType="com.zking.ssm.model.Clazz" resultType="java.util.Map">
    2.     select
    3.     <include refid="Base_Column_List" />
    4.     from t_struts_class
    5.     <where>
    6.       <if test="cname != null and cname != ''">
    7.         cname like CONCAT('%',#{cname},'%')
    8.       if>
    9.       <if test="cid != null and cid != ''">
    10.         cid = #{cid}
    11.       if>
    12.     where>
    13.   select>

    测试：

    1. <%--
    2.   Created by IntelliJ IDEA.
    3.   User: Administrator
    4.   Date: 2022/8/22
    5.   Time: 16:46
    6.   To change this template use File | Settings | File Templates.
    7. --%>
    8. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    9. <html>
    10. <head>
    11.     <title>测试json数据返回title>
    12. head>
    13. <body>
    14.  
    15. <a href="${pageContext.request.contextPath}/clz/json/list">返回list<T>对象a><hr>
    16. <a href="${pageContext.request.contextPath}/clz/json/mapList">返回list<Map>对象a><hr>
    17. <a href="${pageContext.request.contextPath}/clz/json/load?cid=1">返回T对象a><hr>
    18. <a href="${pageContext.request.contextPath}/clz/json/mapLoad?cid=1">返回Map对象a><hr>
    19. <a href="${pageContext.request.contextPath}/clz/json/all">返回混合对象a><hr>
    20.  
    21. body>
    22. html>

     效果：

     

     

     

     

    二，SpringMVC 的全局异常处理

            1.为什么要全局异常处理

     我们知道，系统中异常包括：编译时异常和运行时异常RuntimeException，前者通过捕获异常从而获取异常信息，后者主要通过规范代码开发、测试通过手段减少运行时异常的发生。在开发中，不管是dao层、service层还是controller层，都有可能抛出异常，在springmvc中，能将所有类型的异常处理从各处理过程解耦出来，既保证了相关处理过程的功能较单一，也实现了异常信息的统一处理和维护。

            2.异常处理思路

       系统的dao、service、controller出现异常都通过throws Exception向上抛出，最后由springmvc前端控制器交由异常处理器进行异常处理。springmvc提供全局异常处理器（一个系统只有一个异常处理器）进行统一异常处理。

            3.SpringMVC异常分类   

       1）使用Spring MVC提供的简单异常处理器SimpleMappingExceptionResolver；

       2）实现Spring的异常处理接口HandlerExceptionResolver自定义自己的异常处理器；

       3）使用@ControllerAdvice + @ExceptionHandler

    JsonController ：

    1.      /**
    2.      * 返回List
    3.      * @param req
    4.      * @param clazz
    5.      * @return
    6.      */
    7.     @ResponseBody
    8.     @RequestMapping("/list")
    9.     public List list(HttpServletRequest req, Clazz clazz){
    10.         PageBean pageBean = new PageBean();
    11.         pageBean.setRequest(req);
    12.         if(true) {
    13.             throw new RuntimeException("查询班级信息异常，异常存在于JsonController.list方法");
    14.         }
    15.         List lst = this.clazzBiz.listPager(clazz, pageBean);
    16.         return lst;
    17.     }
    18.  
    19.  
    20.  
    21.    /**
    22.      * 返回List
    23.      * @param req
    24.      * @param clazz
    25.      * @return
    26.      */
    27.     @ResponseBody
    28.     @RequestMapping("/mapList")
    29.     public List mapList(HttpServletRequest req, Clazz clazz){
    30.         PageBean pageBean = new PageBean();
    31.         pageBean.setRequest(req);
    32.         List lst = this.clazzBiz.listMapPager(clazz, pageBean);
    33.         return lst;
    34.     }

    Bizimpl:

    1.  @Override
    2.     public List listMapPager(Clazz clazz, PageBean pageBean) {
    3.         if(true) {
    4.             throw new RuntimeException("查询班级信息异常，异常存在于ClazzBizImpl.list方法");
    5.         }
    6.         return clazzMapper.listMapPager(clazz);
    7.     }

    效果： 

     

    SpringMVC自带的简单异常处理器

            springmvc-servlet.xml

    2.     <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
    3.         
    4.         <property name="defaultErrorView" value="error"/>
    5.         
    6.         <property name="exceptionAttribute" value="ex"/>
    7.         
    8.         <property name="exceptionMappings">
    9.             <props>
    10.                 <prop key="java.lang.RuntimeException">errorprop>
    11.             props>
    12.             
    13.         property>
    14.     bean>

    error.jsp

    ${ex}

     

     

      4. 通过HandlerExceptionResovler接口实现全局异常

    先将上面SpringMVC中关于异常处理的配置取消掉

    全局异常GlobalException.java：

            

    1. package com.ruojuan.ssm.Exception;
    2.  
    3. /**
    4.  * @author ruojuan
    5.  * @site 123456999
    6.  * @company 玉渊工作室
    7.  * @create 2022-08-22 17:16
    8.  */
    9. public class GlobalException extends RuntimeException{
    10.     public GlobalException() {
    11.     }
    12.  
    13.     public GlobalException(String message) {
    14.         super(message);
    15.     }
    16.  
    17.     public GlobalException(String message, Throwable cause) {
    18.         super(message, cause);
    19.     }
    20.  
    21.     public GlobalException(Throwable cause) {
    22.         super(cause);
    23.     }
    24.  
    25.     public GlobalException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
    26.         super(message, cause, enableSuppression, writableStackTrace);
    27.     }
    28. }

    异常处理器 GlobalHandlerExceptionResovler 

    1. package com.ruojuan.ssm.Exception;
    2.  
    3. import org.springframework.stereotype.Component;
    4. import org.springframework.web.servlet.HandlerExceptionResolver;
    5. import org.springframework.web.servlet.ModelAndView;
    6.  
    7. import javax.servlet.http.HttpServletRequest;
    8. import javax.servlet.http.HttpServletResponse;
    9.  
    10. /**
    11.  * @author ruojuan
    12.  * @site 123456999
    13.  * @company 玉渊工作室
    14.  * @create 2022-08-22 17:52
    15.  *
    16.  * 处理全局异常的解析器
    17.  */
    18. @Component
    19. public class GlobalHandlerExceptionResovler implements HandlerExceptionResolver {
    20.  
    21.  
    22.     /**
    23.      *
    24.      * @param httpServletRequest
    25.      * @param httpServletResponse
    26.      * @param o 目标对象
    27.      * @param e
    28.      * @return
    29.      */
    30.     @Override
    31.     public ModelAndView resolveException(HttpServletRequest httpServletRequest,
    32.                                          HttpServletResponse httpServletResponse,
    33.                                          Object o, Exception e) {
    34.         ModelAndView mv = new ModelAndView();
    35.         mv.setViewName("error");
    36.         if (e instanceof GlobalException){
    37.             GlobalException globalException = (GlobalException) e;
    38.             mv.addObject("ex",globalException.getMessage());
    39.             mv.addObject("msg","全局异常,错误码501....");
    40.         }else if (e instanceof RuntimeException){
    41.             RuntimeException runtimeException = (RuntimeException) e;
    42.             mv.addObject("ex",runtimeException.getMessage());
    43.             mv.addObject("msg","运行时异常,错误码601....");
    44.         }
    45.         return mv;
    46.     }
    47. }

    测试代码Controller层的改变

    1.  @ResponseBody
    2.     @RequestMapping("/load")
    3.     public Clazz load(HttpServletRequest req, Clazz clazz){
    4.         if(clazz.getCid() != null){
    5.             List lst = this.clazzBiz.listPager(clazz, null);
    6.             if (true)
    7.                 throw new GlobalException("错误出现在 JsonController.load...");
    8.             return lst.get(0);
    9.         }
    10.         return null;
    11.     }

     

     使用@ControllerAdvice+@ExceptionHandler实现全局异常

    1. package com.ruojuan.ssm.Exception;
    2.  
    3. import org.springframework.web.bind.annotation.ControllerAdvice;
    4. import org.springframework.web.bind.annotation.ExceptionHandler;
    5. import org.springframework.web.servlet.ModelAndView;
    6.  
    7. /**
    8.  * @author ruojuan
    9.  * @site 123456999
    10.  * @company 玉渊工作室
    11.  * @create 2022-08-22 18:10
    12.  */
    13. //@ControllerAdvice
    14.  
    15. public class GlobalExceptionResovler {
    16.  
    17.     @ExceptionHandler
    18.     public ModelAndView handler(Exception e){
    19.         ModelAndView mv = new ModelAndView();
    20.         mv.setViewName("error");
    21.         if (e instanceof GlobalException){
    22.             GlobalException globalException = (GlobalException) e;
    23.             mv.addObject("ex",globalException.getMessage());
    24.             mv.addObject("msg","全局异常....");
    25.         }else if (e instanceof RuntimeException){
    26.             RuntimeException runtimeException = (RuntimeException) e;
    27.             mv.addObject("ex",runtimeException.getMessage());
    28.             mv.addObject("msg","运行时异常....");
    29.         }
    30.         return mv;
    31.     }
    32. }

     全局异常处理JSON返回

    1. package com.ruojuan.ssm.Exception;
    2.  
    3. import org.springframework.web.bind.annotation.ControllerAdvice;
    4. import org.springframework.web.bind.annotation.ExceptionHandler;
    5. import org.springframework.web.bind.annotation.RestControllerAdvice;
    6.  
    7. import java.util.HashMap;
    8. import java.util.Map;
    9.  
    10. /**
    11.  * @author ruojuan
    12.  * @site 123456999
    13.  * @company 玉渊工作室
    14.  * @create 2022-08-22 18:11
    15.  *
    16.  * 当出现异常，统一向前端响应错误后出现的结果
    17.  */
    18. //@ControllerAdvice
    19. @RestControllerAdvice
    20. public class GlobalExceptionJsonResolver {
    21.  
    22.     @ExceptionHandler
    23.     public Map handler(Exception e){
    24.         Map map = new HashMap();
    25.         if (e instanceof GlobalException){
    26.             GlobalException globalException = (GlobalException) e;
    27.             map.put("ex",globalException.getMessage());
    28.             map.put("msg","全局异常 GlobalExceptionResolver,错误码501....");
    29.         }else if (e instanceof RuntimeException){
    30.             RuntimeException runtimeException = (RuntimeException) e;
    31.             map.put("ex",runtimeException.getMessage());
    32.             map.put("msg","运行时异常 GlobalExceptionResolver,错误码601....");
    33.         }
    34.         return map;
    35.     }
    36.  
    37. }

     

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  • 原文地址：https://blog.csdn.net/weixin_67338832/article/details/126471541