• JSON和全局异常处理

    目录

    一：SpringMVC对JSON的支持

    1.JSON的各种类型

    1.1返回list

    2.代码段 

    3.测试 

    效果图 

    二：SpringMVC的全局异常处理

    1.为什么要全局处理

    2.异常处理思路

     3.SpringMVC异常分类 

    案例：

    1.SpringMVC自带的简单异常处理器

    ​编辑     2：HandlerExceptionResovler接口实现全局异常 

    3.ControllerAdvice+@ExceptionHandler实现全局异常 

    4.全局异常+响应封装类 

    一：SpringMVC对JSON的支持

    1.JSON的各种类型

    1.1返回list

    1.  //list
    2.     @RequestMapping("/list")
    3.     public List<Clazz> list(HttpServletRequest request,Clazz clazz){
    4.         PageBean pageBean =new PageBean();
    5.         pageBean.setRequest(request);
    6.         if(true)
    7.         throw new RuntimeException("查询班级信息异常,异常存在于JsonController。list");
    8.         return this.classBiz.listPager(clazz,pageBean);
    9.     }

    1.2返回list

    1.  //list
    2.     @RequestMapping("/listMap")
    3.     public List<Map> listMap(HttpServletRequest request, Clazz clazz){
    4.         PageBean pageBean =new PageBean();
    5.         pageBean.setRequest(request);
    6.         return this.classBiz.listMapPager(clazz,pageBean);
    7.     }

    1.3返回T

    1.  @RequestMapping("/load")
    2.     public Clazz load(HttpServletRequest request, Clazz clazz){
    3.         PageBean pageBean =new PageBean();
    4.         pageBean.setRequest(request);
    5.         if(true)
    6.             throw  new GlobalException("系统繁忙，请参考E007");
    7.         return this.classBiz.listPager(clazz,pageBean).get(0);
    8.     }

    1.4返回Map

    1. //    Map
    2.     @RequestMapping("/map")
    3.     public Map map(HttpServletRequest request, Clazz clazz){
    4.         PageBean pageBean =new PageBean();
    5.         pageBean.setRequest(request);
    6.         return this.classBiz.listMapPager(clazz,pageBean).get(0);
    7.     }

    1.5返回混合

    1.  @RequestMapping("/hunhe")
    2.     public Map hunhe(HttpServletRequest request, Clazz clazz){
    3.         PageBean pageBean =new PageBean();
    4.         pageBean.setRequest(request);
    5.         List<Clazz> lst= this.classBiz.listPager(clazz,pageBean);
    6.         Map map = new HashMap();
    7.         map.put("data",lst);
    8.         map.put("pagebean",pageBean);
    9.         return map;
    10.     }

    2.代码段 

    导入pom依赖

    1. <!--用来springMVC支持json数据转换-->
    2.     <dependency>
    3.       <groupId>com.fasterxml.jackson.core</groupId>
    4.       <artifactId>jackson-databind</artifactId>
    5.       <version>2.9.3</version>
    6.     </dependency>
    7.     <dependency>
    8.       <groupId>com.fasterxml.jackson.core</groupId>
    9.       <artifactId>jackson-core</artifactId>
    10.       <version>2.9.3</version>
    11.     </dependency>
    12.     <dependency>
    13.       <groupId>com.fasterxml.jackson.core</groupId>
    14.       <artifactId>jackson-annotations</artifactId>
    15.       <version>2.9.3</version>
    16.     </dependency>

    ClazzMapper.xml

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

    ClazzMapper.java

     List listMapPager(Clazz clazz);

    ClazzBiz

    List listMapPager(Clazz clazz, PageBean pageBean);

    3.测试 

    1. <%--
    2.   Created by IntelliJ IDEA.
    3.   User: zjjt
    4.   Date: 2022-8-22
    5.   Time: 17:09
    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返回</title>
    12. </head>
    13. <body>
    14.  
    15. <a href="${pageContext.request.contextPath}/clz/json/list">返回list&lt;T&gt;对象</a><hr>
    16. <a href="${pageContext.request.contextPath}/clz/json/listMap">返回list&lt;Map&gt;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/map?cid=1">返回Map对象</a><hr>
    19. <a href="${pageContext.request.contextPath}/clz/json/hunhe">返回混合对象</a><hr>
    20.  
    21. </body>
    22. </html>

    效果图 

     

    二：SpringMVC的全局异常处理

    1.为什么要全局处理

     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

    案例：

    1.SpringMVC自带的简单异常处理器

    SpringMVC_Servlet.xml配置文件

    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>

     

      
       2：HandlerExceptionResovler接口实现全局异常 

    1. package com.zhoujuan.ssm.excetion;
    2.  
    3. import org.springframework.web.bind.annotation.ExceptionHandler;
    4. import org.springframework.web.servlet.ModelAndView;
    5.  
    6. /**
    7.  * @author zhuojuan
    8.  * @site www.zhoujuan.com
    9.  * @company 玉渊工作室
    10.  * @create  2022-08-22 18:44
    11.  */
    12. //@ControllerAdvice
    13. public class GlobalExceptionResovler {
    14.  
    15.     @ExceptionHandler
    16.     public ModelAndView handler(Exception e){
    17.         ModelAndView mv = new ModelAndView();
    18.         mv.setViewName("error");
    19.         if(e instanceof GlobalException){
    20.             GlobalException exception = (GlobalException) e;
    21.             mv.addObject("ex",exception.getMessage());
    22.             mv.addObject("msg","全局异常，错误码501");
    23.         }else if(e instanceof GlobalException){
    24.             RuntimeException exception = (RuntimeException) e;
    25.             mv.addObject("ex",exception.getMessage());
    26.             mv.addObject("msg","运行时异常，错误码601");
    27.         }
    28.         return mv;
    29.     }
    30. }

     

     

    3.ControllerAdvice+@ExceptionHandler实现全局异常 

    GlobalException

    1. package com.zhoujuan.ssm.excetion;
    2.  
    3. /**
    4.  * @author zhuojuan
    5.  * @site www.zhoujuan.com
    6.  * @company 玉渊工作室
    7.  * @create  2022-08-22 18:21
    8.  */
    9.  
    10. public class GlobalException extends RuntimeException {
    11.  
    12.  
    13.     public GlobalException() {
    14.     }
    15.  
    16.     public GlobalException(String message) {
    17.         super(message);
    18.     }
    19.  
    20.     public GlobalException(String message, Throwable cause) {
    21.         super(message, cause);
    22.     }
    23.  
    24.     public GlobalException(Throwable cause) {
    25.         super(cause);
    26.     }
    27.  
    28.     public GlobalException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
    29.         super(message, cause, enableSuppression, writableStackTrace);
    30.     }
    31. }

    GlobalHandlerExceptionResovler 

    1. package com.zhoujuan.ssm.excetion;
    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 zhuojuan
    12.  * @site www.zhoujuan.com
    13.  * @company 玉渊工作室
    14.  * @create  2022-08-22 18:27
    15.  *
    16.  * 处理全局异常的解析器
    17.  */
    18.  @Component
    19. public class GlobalHandlerExceptionResovler implements HandlerExceptionResolver {
    20.     /**
    21.      *
    22.      * @param httpServletRequest
    23.      * @param httpServletResponse
    24.      * @param o 目标对象
    25.      * @param e 目标对象执行，出现的异常对象
    26.      * @return
    27.      */
    28.     @Override
    29.     public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
    30.         ModelAndView mv = new ModelAndView();
    31.         mv.setViewName("error");
    32.        if(e instanceof GlobalException){
    33.            GlobalException exception = (GlobalException) e;
    34.            mv.addObject("ex",exception.getMessage());
    35.            mv.addObject("msg","全局异常，错误码501");
    36.        }else if(e instanceof GlobalException){
    37.            RuntimeException exception = (RuntimeException) e;
    38.            mv.addObject("ex",exception.getMessage());
    39.            mv.addObject("msg","运行时异常，错误码601");
    40.        }
    41.         return mv;
    42.     }
    43. }
    1.  @Override
    2.     public List<Map> 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");
    5.         return clazzMapper.listMapPager(clazz);
    6.     }

     error.jsp

    1. <%--
    2.   Created by IntelliJ IDEA.
    3.   User: zjjt
    4.   Date: 2022-8-22
    5.   Time: 18:14
    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>错误信息界面</title>
    12. </head>
    13. <body>
    14. ${msg}
    15. ${ex}
    16. </body>
    17. </html>

    4.全局异常+响应封装类 

     GlobalExceptionResovler 

    1. package com.zhoujuan.ssm.excetion;
    2.  
    3. import org.springframework.web.bind.annotation.ExceptionHandler;
    4. import org.springframework.web.servlet.ModelAndView;
    5.  
    6. /**
    7.  * @author zhuojuan
    8.  * @site www.zhoujuan.com
    9.  * @company 玉渊工作室
    10.  * @create  2022-08-22 18:44
    11.  */
    12. //@ControllerAdvice
    13. public class GlobalExceptionResovler {
    14.  
    15.     @ExceptionHandler
    16.     public ModelAndView handler(Exception e){
    17.         ModelAndView mv = new ModelAndView();
    18.         mv.setViewName("error");
    19.         if(e instanceof GlobalException){
    20.             GlobalException exception = (GlobalException) e;
    21.             mv.addObject("ex",exception.getMessage());
    22.             mv.addObject("msg","全局异常，错误码501");
    23.         }else if(e instanceof GlobalException){
    24.             RuntimeException exception = (RuntimeException) e;
    25.             mv.addObject("ex",exception.getMessage());
    26.             mv.addObject("msg","运行时异常，错误码601");
    27.         }
    28.         return mv;
    29.     }
    30. }

    GlobalExceptionResovler 2

    1. package com.zhoujuan.ssm.excetion;
    2.  
    3. import org.springframework.web.bind.annotation.ExceptionHandler;
    4. import org.springframework.web.bind.annotation.RestControllerAdvice;
    5.  
    6. import java.util.HashMap;
    7. import java.util.Map;
    8.  
    9. /**
    10.  * @author zhuojuan
    11.  * @site www.zhoujuan.com
    12.  * @company 玉渊工作室
    13.  * @create  2022-08-22 18:44
    14.  *
    15.  * 当出现异常，统一向前端响应错误信息的json对象数据
    16.  */
    17. //@ControllerAdvice
    18.     @RestControllerAdvice
    19. public class GlobalExceptionResovler2 {
    20.  
    21.     @ExceptionHandler
    22.     public Map handler(Exception e){
    23.         Map map = new HashMap();
    24.         if(e instanceof GlobalException){
    25.             GlobalException exception = (GlobalException) e;
    26.             map.put("ex",exception.getMessage());
    27.             map.put("msg","全局异常，错误码501");
    28.         }else if(e instanceof GlobalException){
    29.             RuntimeException exception = (RuntimeException) e;
    30.             map.put("ex",exception.getMessage());
    31.             map.put("msg","运行时异常，错误码601");
    32.         }
    33.         return map;
    34.     }
    35. }

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  • 原文地址：https://blog.csdn.net/m0_67864917/article/details/126472015