SpringMVC（Json和全局异常处理）

目录

1. Json三种数据格式

1.1 添加相关依赖和配置文件

1.2 对象格式

1.3 list格式

1.4 混合格式

 2. SpringMVC全局异常处理

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

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

2.3 使用@ControllerAdvice + @ExceptionHandle

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1. Json三种数据格式

 1.1 添加相关依赖和配置文件

• 在pom.xml文件里面添加以下依赖 

   <dependency>
     <groupId>com.fasterxml.jackson.coregroupId>
     <artifactId>jackson-databindartifactId>
     <version>2.9.3version>
   dependency>
   <dependency>
     <groupId>com.fasterxml.jackson.coregroupId>
     <artifactId>jackson-coreartifactId>
     <version>2.9.3version>
   dependency>
   <dependency>
     <groupId>com.fasterxml.jackson.coregroupId>
     <artifactId>jackson-annotationsartifactId>
     <version>2.9.3version>
   dependency> 

• 在spring-mvc.xml文件里面添加以下配置

   <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">
        
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8value>
                <value>text/json;charset=UTF-8value>
                <value>application/json;charset=UTF-8value>
            list>
        property>
   bean>

 1.2 对象格式

 在请求处理方法中添加@ResponseBody注解，将返回结果直接转换成JSON

 注：此请求处理方法返回的已经不是视图了 

    @RequestMapping("/toJsonLoadBook")
    @ResponseBody
    public Book toJsonLoadBook(Book book){
        Book b = iBookService.selectByPrimaryKey(book.getBookId());
        return b;
    }

 1.3 list格式

    @RequestMapping("/toJsonListBook")
    @ResponseBody
    public List toJsonListBook(){
        List list = iBookService.listBook(null, null);
        return list;
    }

 1.4 混合格式

• 单个 

    @RequestMapping("/toJsonMap1")
    @ResponseBody
    public Map toJsonMap1(Book book) {
        Map map = new HashMap<>();
        map.put("total", 888);
        map.put("success", true);
        //获取数据
        List> maps = iBookService.jsonMap(book.getBookId());
        map.put("data", maps);
        return map;
    }

•  多个

    @RequestMapping("/toJsonMap2")
    @ResponseBody
    public Map toJsonMap2(Book book) {
        Map map = new HashMap<>();
        map.put("total", 888);
        map.put("success", true);
        //获取数据
        List> maps = iBookService.jsonMap1(book);
        map.put("data", maps);
        return map;
    }

 2. SpringMVC全局异常处理

• 注！！！需先创建一个error.jsp抛出异常而呈现在前端页面的类 

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

• 在spring-mvc.xml文件里面添加以下配置

   <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
       
       <property name="defaultErrorView" value="error"/>
        
       <property name="exceptionAttribute" value="ex"/>
        
       <property name="exceptionMappings">
           <props>
               <prop key="java.lang.RuntimeException">errorprop>
           props>
           
       property>
   bean> 

• Controller层代码

 在controller层验证判断id大与500就会抛出异常在spring-mvc.xml配置文件加上的配置就会处理异常抛出跳转到你创建的error.jsp那个页面

    @RequestMapping("/toJsonLoadBook")
    @ResponseBody
    public Book toJsonLoadBook(Book book){
        if(book.getBookId()>=500){
            throw new RuntimeException("书本ID大于500，抛出异常");
        }
        Book b = iBookService.selectByPrimaryKey(book.getBookId());
        b.setDate(new Date());
        return b;
    }

2.2实现Spring的异常处理接口HandlerExceptionResolver自定义自己的异常处理器；

package com.jmh.mybatis.exception;
 
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
/**
 * 全局异常处理
 */
@Component
public class GloabException implements HandlerExceptionResolver {
 
 
    @Override
    public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, java.lang.Exception e) {
        //定义一个视图
        ModelAndView mv=new ModelAndView();
        //判断ex是否和Run异常有关系
        if(e instanceof RuntimeException){
            //强转
            RuntimeException e1=(RuntimeException)e;
            //将获取到的数据保存到作用域里面
            mv.addObject("msg", e1.getMessage());
        }
        //设置跳转页面
        mv.setViewName("error");
        return mv;
    }
}

• Controller层

    @RequestMapping("/toJsonLoadBook")
    @ResponseBody
    public Book toJsonLoadBook(Book book){
        if(book.getBookId()>=500){
            throw new RuntimeException("书本ID大于500，抛出异常");
        }
        Book b = iBookService.selectByPrimaryKey(book.getBookId());
        b.setDate(new Date());
        return b;
    }

 2.3 使用@ControllerAdvice + @ExceptionHandler

• 定义异常通知 

package com.jmh.mybatis.exception;
 
/**
 * 异常通知
 */
public class IdOverException extends RuntimeException{
    public IdOverException() {
        super();
    }
 
    public IdOverException(String message) {
        super(message);
    }
 
    public IdOverException(String message, Throwable cause) {
        super(message, cause);
    }
 
    public IdOverException(Throwable cause) {
        super(cause);
    }
 
    protected IdOverException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
    }
}

•  异常类

package com.jmh.mybatis.exception;
 
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.servlet.ModelAndView;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
 
@ControllerAdvice
public class Exception {
 
    @ExceptionHandler
    public ModelAndView resolveException(java.lang.Exception e) {
        //定义一个视图
        ModelAndView mv=new ModelAndView();
        //判断ex是否和Run异常有关系
        if(e instanceof RuntimeException){
            //强转
            RuntimeException e1=(RuntimeException)e;
            //将获取到的数据保存到作用域里面
            mv.addObject("msg", e1.getMessage());
        }
        //设置跳转页面
        mv.setViewName("error");
        return mv;
    }
}

•  Controller层

    @RequestMapping("/toJsonLoadBook")
    @ResponseBody
    public Book toJsonLoadBook(Book book){
        if(book.getBookId()>=500){
            throw new IdOverException("书本ID大于500，抛出异常");
        }
        Book b = iBookService.selectByPrimaryKey(book.getBookId());
        b.setDate(new Date());
        return b;
    }

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