目录
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
一、json解析
JSON的三种形式:
①、{}----->JSON对象
②、[]------>JSON数组
③、{
msg=" ",
code=" ",
data=[]
}------>对象数组
SpringMVC要如果产生上述的三种形式JSON?
步骤:
1、导入pom.xml依赖
2、配置Springmvc.xml适配器
3、使用注解@responseBody 能够将任何的数据转成json对象
①、pom.xml依赖
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.3</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.3</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.3</version>
</dependency>
②、Springmvc.xml适配器
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
<property name="messageConverters">
<list>
<ref bean="mappingJackson2HttpMessageConverter"/>
</list>
</property>
</bean>
<bean id="mappingJackson2HttpMessageConverter"
class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<!--处理中文乱码以及避免IE执行AJAX时,返回JSON出现下载文件-->
<property name="supportedMediaTypes">
<list>
<value>text/html;charset=UTF-8</value>
<value>text/json;charset=UTF-8</value>
<value>application/json;charset=UTF-8</value>
</list>
</property>
</bean>
③、后端代码编写
先编写在ClazzMapper.xml中编写一个查询的方法
<select id="listMapPager" resultType="java.util.Map" parameterType="com.mgy.ssm.model.Clazz" >
select
<include refid="Base_Column_List" />
from t_struts_class
<where>
<if test="cname !=null and cname != ''">
and cname like concat('%',#{cname},'%')
</if>
<if test="cid !=null and cid != ''">
and cid=#{cid}
</if>
</where>
</select>
将listMapPager该方法在ClazzMapper、ClazzBiz和ClazzBizImpl中实现出来,重新创建一个新类
package com.mgy.ssm.controller;
import com.mgy.ssm.biz.ClazzBiz;
import com.mgy.ssm.model.Clazz;
import com.mgy.ssm.util.PageBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletRequest;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author 云鹤衫
* @site www.yunheshan.com
* @company xxx公司
* @create 2022-08-22 18:51
*/
@Controller
@RequestMapping("/clz/json")
public class JsonController {
@Autowired
private ClazzBiz clazzBiz;
@ResponseBody
@RequestMapping("/clzEdit")
public String clzEdit(){
System.out.println("JsonController.clzEdit");
return "clzEdit";
}
// List<T>
@ResponseBody
@RequestMapping("/list")
public List<Clazz> list(HttpServletRequest req,Clazz clazz){
PageBean pageBean=new PageBean();
pageBean.setRequest(req);
// [{},{}]
return this.clazzBiz.listPager(clazz,pageBean);
}
// List<Map>
@ResponseBody
@RequestMapping("/listMap")
public List<Map> listMapPager(HttpServletRequest req, Clazz clazz){
PageBean pageBean=new PageBean();
pageBean.setRequest(req);
// [{},{}]
return this.clazzBiz.listMapPager(clazz,pageBean);
}
// List<Map>
@ResponseBody
@RequestMapping("/map")
public Map map(HttpServletRequest req, Clazz clazz){
PageBean pageBean=new PageBean();
pageBean.setRequest(req);
// {}
return this.clazzBiz.listMapPager(clazz,pageBean).get(0);
}
// T
@ResponseBody
@RequestMapping("/load")
public Clazz load(HttpServletRequest req, Clazz clazz){
// http://localhost:8080/clz/json/load?cid=2
PageBean pageBean=new PageBean();
pageBean.setRequest(req);
// {}
return this.clazzBiz.listPager(clazz,pageBean).get(0);
}
/* {
msg:"",
code:200,
data:[],
pageBean:{}
}*/
@ResponseBody
@RequestMapping("/hunhe")
public Map hunhe(HttpServletRequest req, Clazz clazz){
// http://localhost:8080/clz/json/load?cid=2
PageBean pageBean=new PageBean();
pageBean.setRequest(req);
List<Clazz> lst = this.clazzBiz.listPager(clazz, pageBean);
Map map=new HashMap();
map.put("data",lst);
map.put("pagebean",pageBean);
return map;
}
}
④、前端代码编写
index.jsp
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2022/8/22
Time: 19:35
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>测试json数据返回</title>
</head>
<body>
<a href="${pageContext.request.contextPath}/clz/json/list">返回list<T>对象</a><hr>
<a href="${pageContext.request.contextPath}/clz/json/listMap">返回list<Map>对象</a><hr>
<a href="${pageContext.request.contextPath}/clz/json/load?cid=1">返回T对象</a><hr>
<a href="${pageContext.request.contextPath}/clz/json/map?cid=1">返回Map对象</a><hr>
<a href="${pageContext.request.contextPath}/clz/json/hunhe">返回混合对象</a><hr>
</body>
</html>
效果:
list方法效果:
listMap方法效果:
load方法效果:
map方法效果:
hunhe方法效果:
二、全局异常处理
1、为什么要用全局异常处理
2、SpringMVC异常分类
1)使用Spring MVC提供的简单异常处理器SimpleMappingExceptionResolver
在JsonController类上加入@ResController注解
@ResponseBody+@controller=@ResController
Controller层
@RequestMapping("/list")
public List<Clazz> list(HttpServletRequest req,Clazz clazz){
PageBean pageBean=new PageBean();
pageBean.setRequest(req);
if(true)
throw new RuntimeException("查询班级异常,异常存在于JsonController.list方法中");
// [{},{}]
return this.clazzBiz.listPager(clazz,pageBean);
}
@RequestMapping("/load")
public Clazz load(HttpServletRequest req, Clazz clazz){
// http://localhost:8080/clz/json/load?cid=2
PageBean pageBean=new PageBean();
pageBean.setRequest(req);
if(true)
throw new GlobalException("系统繁忙,请参考E007l;");
// {}
return this.clazzBiz.listPager(clazz,pageBean).get(0);
}
Service层
@Override
public List<Map> listMapPager(Clazz clazz, PageBean pageBean) {
if(true)
throw new RuntimeException("查询班级异常,ClazzBizImpl.list方法中");
return clazzMapper.listMapPager(clazz);
}
效果:
点击图上两个方法
返回list<T>对象效果:
返回list<Map>对象效果:
2)实现Spring的异常处理接口HandlerExceptionResolver自定义自己的异常处理器
配置SpringMVC
<!-- springmvc提供的简单异常处理器 -->
<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<!-- 定义默认的异常处理页面 -->
<property name="defaultErrorView" value="error"/>
<!-- 定义异常处理页面用来获取异常信息的变量名,也可不定义,默认名为exception -->
<property name="exceptionAttribute" value="ex"/>
<!-- 定义需要特殊处理的异常,这是重要点 -->
<property name="exceptionMappings">
<props>
<prop key="java.lang.RuntimeException">error</prop>
</props>
<!-- 还可以定义其他的自定义异常 -->
</property>
</bean>
Error.jsp
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2022/8/23
Time: 18:25
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>错误信息页面</title>
</head>
<body>
${ex}
</body>
</html>
效果:
3)使用@ControllerAdvice + @ExceptionHandler
先将上面SpringMVC中关于异常处理的配置取消掉
先建立一个类作为全局异常类
package com.mgy.ssm.exception;
/**
* @author 云鹤衫
* @site www.yunheshan.com
* @company xxx公司
* @create 2022-08-23 18:30
*/
public class GlobalException extends RuntimeException{
public GlobalException() {
}
public GlobalException(String message) {
super(message);
}
public GlobalException(String message, Throwable cause) {
super(message, cause);
}
public GlobalException(Throwable cause) {
super(cause);
}
public GlobalException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
super(message, cause, enableSuppression, writableStackTrace);
}
}
在建立一个类作为异常处理器
package com.mgy.ssm.exception;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.ModelAndView;
/**
* @author 云鹤衫
* @site www.yunheshan.com
* @company xxx公司
* @create 2022-08-23 19:09
*/
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler
public ModelAndView handler(Exception e){
ModelAndView mv=new ModelAndView();
mv.setViewName("error");
if(e instanceof GlobalException){
GlobalException exception=(GlobalException)e;
mv.addObject("ex",exception.getMessage());
mv.addObject("msg","全局异常,GlobalExceptionHandler,错误码501");
}else if(e instanceof RuntimeException){
RuntimeException exception=(RuntimeException)e;
mv.addObject("ex",exception.getMessage());
mv.addObject("msg","运行时异常,GlobalExceptionHandler,错误码601");
}
return mv;
}
}
效果:
三、json统一处理
将之前异常处理器上的注解注销
然后重新建立一个异常处理器
package com.mgy.ssm.exception;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.ModelAndView;
import java.util.HashMap;
import java.util.Map;
/**
* @author 云鹤衫
* @site www.yunheshan.com
* @company xxx公司
* @create 2022-08-23 19:09
*
* 当出现异常,统一向前端响应错误信息的json对象数据
*/
//@ControllerAdvice
public class GlobalExceptionHandler2 {
@ExceptionHandler
public Map handler(Exception e){
Map map=new HashMap();
if(e instanceof GlobalException){
GlobalException exception=(GlobalException)e;
map.put("ex",exception.getMessage());
map.put("msg","全局异常,GlobalExceptionHandler,错误码501");
}else if(e instanceof RuntimeException){
RuntimeException exception=(RuntimeException)e;
map.put("ex",exception.getMessage());
map.put("msg","运行时异常,GlobalExceptionHandler,错误码601");
}
return map;
}
}
效果:
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