SpringMVC之JSON返回&异常处理机制

json处理
统一异常处理

1.json处理

//pom.xml
<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.example</groupId>
  <artifactId>zljzyssm</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>zljzyssm Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.plugin.version>3.7.0</maven.compiler.plugin.version>

    <!--添加jar包依赖-->
    <!--1.spring 5.0.2.RELEASE相关-->
    <spring.version>5.0.2.RELEASE</spring.version>
    <!--2.mybatis相关-->
    <mybatis.version>3.4.5</mybatis.version>
    <!--mysql-->
    <mysql.version>5.1.44</mysql.version>
    <!--pagehelper分页jar依赖-->
    <pagehelper.version>5.1.2</pagehelper.version>
    <!--mybatis与spring集成jar依赖-->
    <mybatis.spring.version>1.3.1</mybatis.spring.version>
    <!--3.dbcp2连接池相关 druid-->
    <commons.dbcp2.version>2.1.1</commons.dbcp2.version>
    <commons.pool2.version>2.4.3</commons.pool2.version>
    <!--4.log日志相关-->
    <log4j2.version>2.9.1</log4j2.version>
    <log4j2.disruptor.version>3.2.0</log4j2.disruptor.version>
    <slf4j.version>1.7.13</slf4j.version>
    <!--5.其他-->
    <junit.version>4.12</junit.version>
    <servlet.version>4.0.0</servlet.version>
    <lombok.version>1.18.2</lombok.version>

    <mybatis.ehcache.version>1.1.0</mybatis.ehcache.version>
    <ehcache.version>2.10.0</ehcache.version>

    <redis.version>2.9.0</redis.version>
    <redis.spring.version>1.7.1.RELEASE</redis.spring.version>
    <jackson.version>2.9.3</jackson.version>
    <jstl.version>1.2</jstl.version>
    <standard.version>1.1.2</standard.version>
    <tomcat-jsp-api.version>8.0.47</tomcat-jsp-api.version>
    <commons-fileupload.version>1.3.3</commons-fileupload.version>
    <hibernate-validator.version>5.0.2.Final</hibernate-validator.version>

    <shiro.version>1.3.2</shiro.version>
  </properties>


  <dependencies>
    <!--1.spring相关-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-beans</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-orm</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aspects</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${spring.version}</version>
    </dependency>


    <!--2.mybatis相关-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>${mybatis.version}</version>
    </dependency>
    <!--mysql-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>${mysql.version}</version>
    </dependency>
    <!--pagehelper分页插件jar包依赖-->
    <dependency>
      <groupId>com.github.pagehelper</groupId>
      <artifactId>pagehelper</artifactId>
      <version>${pagehelper.version}</version>
    </dependency>
    <!--mybatis与spring集成jar包依赖-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>${mybatis.spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context-support</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <!--mybatis与ehcache整合-->
    <dependency>
      <groupId>org.mybatis.caches</groupId>
      <artifactId>mybatis-ehcache</artifactId>
      <version>${mybatis.ehcache.version}</version>
    </dependency>
    <!--ehcache依赖-->
    <dependency>
      <groupId>net.sf.ehcache</groupId>
      <artifactId>ehcache</artifactId>
      <version>${ehcache.version}</version>
    </dependency>

    <dependency>
      <groupId>redis.clients</groupId>
      <artifactId>jedis</artifactId>
      <version>${redis.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework.data</groupId>
      <artifactId>spring-data-redis</artifactId>
      <version>${redis.spring.version}</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>${jackson.version}</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>${jackson.version}</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-annotations</artifactId>
      <version>${jackson.version}</version>
    </dependency>

    <!--3.dbcp2连接池相关-->
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-dbcp2</artifactId>
      <version>${commons.dbcp2.version}</version>
      <exclusions>
        <exclusion>
          <artifactId>commons-pool2</artifactId>
          <groupId>org.apache.commons</groupId>
        </exclusion>
      </exclusions>
    </dependency>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-pool2</artifactId>
      <version>${commons.pool2.version}</version>
    </dependency>

    <!--springmvc依赖-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <!--4.log日志相关依赖-->

    <!-- log4j2日志相关依赖 -->
    <!-- log配置：Log4j2 + Slf4j -->
    <!-- slf4j核心包-->
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>${slf4j.version}</version>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>jcl-over-slf4j</artifactId>
      <version>${slf4j.version}</version>
      <scope>runtime</scope>
    </dependency>

    <!--核心log4j2jar包-->
    <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-api</artifactId>
      <version>${log4j2.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-core</artifactId>
      <version>${log4j2.version}</version>
    </dependency>
    <!--用于与slf4j保持桥接-->
    <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-slf4j-impl</artifactId>
      <version>${log4j2.version}</version>
    </dependency>
    <!--web工程需要包含log4j-web，非web工程不需要-->
    <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-web</artifactId>
      <version>${log4j2.version}</version>
      <scope>runtime</scope>
    </dependency>

    <!--需要使用log4j2的AsyncLogger需要包含disruptor-->
    <dependency>
      <groupId>com.lmax</groupId>
      <artifactId>disruptor</artifactId>
      <version>${log4j2.disruptor.version}</version>
    </dependency>

    <!--5.其他-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>${junit.version}</version>
      <!--      <scope>test</scope>-->
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>${servlet.version}</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>${lombok.version}</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>${jstl.version}</version>
    </dependency>
    <dependency>
      <groupId>taglibs</groupId>
      <artifactId>standard</artifactId>
      <version>${standard.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.tomcat</groupId>
      <artifactId>tomcat-jsp-api</artifactId>
      <version>${tomcat-jsp-api.version}</version>
    </dependency>
    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>${commons-fileupload.version}</version>
    </dependency>

    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-validator</artifactId>
      <version>${hibernate-validator.version}</version>
    </dependency>

    <!--shiro依赖-->
    <dependency>
      <groupId>org.apache.shiro</groupId>
      <artifactId>shiro-core</artifactId>
      <version>${shiro.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.shiro</groupId>
      <artifactId>shiro-web</artifactId>
      <version>${shiro.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.shiro</groupId>
      <artifactId>shiro-spring</artifactId>
      <version>${shiro.version}</version>
    </dependency>
  </dependencies>

  <build>
    <finalName>zljzyssm</finalName>

    <resources>
      <!--解决mybatis-generator-maven-plugin运行时没有将XxxMapper.xml文件放入target文件夹的问题-->
      <resource>
        <directory>src/main/java</directory>
        <includes>
          <include>**/*.xml</include>
        </includes>
      </resource>
      <!--解决mybatis-generator-maven-plugin运行时没有将jdbc.properites文件放入target文件夹的问题-->
      <resource>
        <directory>src/main/resources</directory>
        <includes>
          <include>jdbc.properties</include>
          <include>*.xml</include>
        </includes>
      </resource>
    </resources>

    <plugins>

      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>${maven.compiler.plugin.version}</version>
        <configuration>
          <source>${maven.compiler.source}</source>
          <target>${maven.compiler.target}</target>
          <encoding>${project.build.sourceEncoding}</encoding>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.mybatis.generator</groupId>
        <artifactId>mybatis-generator-maven-plugin</artifactId>
        <version>1.3.2</version>
        <dependencies>
          <!--使用Mybatis-generator插件不能使用太高版本的mysql驱动 -->
          <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
          </dependency>
        </dependencies>
        <configuration>
          <overwrite>true</overwrite>
        </configuration>
      </plugin>

    </plugins>
  </build>
</project>

package com.zlj.model;

import com.fasterxml.jackson.annotation.JsonIgnore;
import lombok.ToString;
import org.hibernate.validator.constraints.NotBlank;

import javax.validation.constraints.NotNull;

@ToString
public class Stu {
        @NotNull(message = "学生编号不能为空")
//    @Size(max = 100,min = 10,message = "大小必须在10至100之间")
        protected Integer sid;

        @NotBlank(message = "学生名不能为空")
        protected String same;

        @NotBlank(message = "学生年龄不能为空")
        protected Integer sage;
        @JsonIgnore
        private String spic="暂无图片";

    public Stu(Integer sid, String same, Integer sage, String spic) {
        this.sid = sid;
        this.same = same;
        this.sage = sage;
        this.spic = spic;
    }

    public Integer getSid() {
        return sid;
    }

    public void setSid(Integer sid) {
        this.sid = sid;
    }

    public String getSame() {
        return same;
    }

    public void setSame(String same) {
        this.same = same;
    }

    public Integer getSage() {
        return sage;
    }

    public void setSage(Integer sage) {
        this.sage = sage;
    }

    public String getSpic() {
        return spic;
    }

    public void setSpic(String spic) {
        this.spic = spic;
    }

    public Stu() {
    }
}

stu类里@JsonIgnore:隐藏信息

//StuMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.zlj.mapper.StuMapper" >
  <resultMap id="BaseResultMap" type="com.zlj.model.Stu" >
    <constructor >
      <idArg column="sid" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="same" jdbcType="VARCHAR" javaType="java.lang.String" />
      <arg column="sage" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="spic" jdbcType="VARCHAR" javaType="java.lang.String" />
    </constructor>
  </resultMap>
  <sql id="Base_Column_List" >
    sid, same, sage, spic
  </sql>

  <select id="selectByCon" resultType="com.zlj.model.Stu" parameterType="com.zlj.model.Stu">
    select
    <include refid="Base_Column_List" />
    from student
    <where>
      <if test="same != null">
        and same like concat('%',#{same},'%')
      </if>
    </where>
  </select>
<!--  mapListPager-->
  <select id="mapListPager" resultType="java.util.Map" parameterType="com.zlj.model.Stu">
    select
    <include refid="Base_Column_List" />
    from student
    <where>
      <if test="same != null">
        and same like concat('%',#{same},'%')
      </if>
    </where>
  </select>

  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select
    <include refid="Base_Column_List" />
    from student
    where sid = #{sid,jdbcType=INTEGER}
  </select>

  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from student
    where sid = #{sid,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.zlj.model.Stu" >
    insert into student (sid, same, sage,
      spic)
    values (#{sid,jdbcType=INTEGER}, #{same,jdbcType=VARCHAR}, #{sage,jdbcType=INTEGER},
      #{spic,jdbcType=VARCHAR})
  </insert>
  <insert id="insertSelective" parameterType="com.zlj.model.Stu" >
    insert into student
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="sid != null" >
        sid,
      </if>
      <if test="same != null" >
        same,
      </if>
      <if test="sage != null" >
        sage,
      </if>
      <if test="spic != null" >
        spic,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="sid != null" >
        #{sid,jdbcType=INTEGER},
      </if>
      <if test="same != null" >
        #{same,jdbcType=VARCHAR},
      </if>
      <if test="sage != null" >
        #{sage,jdbcType=INTEGER},
      </if>
      <if test="spic != null" >
        #{spic,jdbcType=VARCHAR},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.zlj.model.Stu" >
    update student
    <set >
      <if test="same != null" >
        same = #{same,jdbcType=VARCHAR},
      </if>
      <if test="sage != null" >
        sage = #{sage,jdbcType=INTEGER},
      </if>
      <if test="spic != null" >
        spic = #{spic,jdbcType=VARCHAR},
      </if>
    </set>
    where sid = #{sid,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.zlj.model.Stu" >
    update student
    set same = #{same,jdbcType=VARCHAR},
      sage = #{sage,jdbcType=INTEGER},
      spic = #{spic,jdbcType=VARCHAR}
    where sid = #{sid,jdbcType=INTEGER}
  </update>
</mapper>

package com.zlj.mapper;

import com.zlj.model.Stu;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Map;

@Repository
public interface StuMapper {
    int deleteByPrimaryKey(Integer sid);

    int insert(Stu record);

    int insertSelective(Stu record);

    Stu selectByPrimaryKey(Integer sid);

    int updateByPrimaryKeySelective(Stu record);

    int updateByPrimaryKey(Stu record);

    List<Stu> selectByCon(Stu stu);

    List<Map> mapListPager(Stu stu, Object o);
    
}

package com.zlj.biz;

import com.zlj.model.Stu;
import com.zlj.util.PageBean;

import java.util.List;
import java.util.Map;

/**
 * @author zlj
 * @create 2023-09-07 17:09
 */
public interface StuBiz {

    int deleteByPrimaryKey(Integer sid);

    int insert(Stu record);

    int insertSelective(Stu record);

    Stu selectByPrimaryKey(Integer sid);

    int updateByPrimaryKeySelective(Stu record);

    int updateByPrimaryKey(Stu record);

    List<Stu> ListPager(Stu stu, PageBean PageBean);

    List<Map> mapListPager(Stu stu, Object o);
}

package com.zlj.biz.Impl;

import com.zlj.biz.StuBiz;
import com.zlj.mapper.StuMapper;
import com.zlj.model.Stu;
import com.zlj.util.PageBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Map;

/**
 * @author zlj
 * @create 2023-09-08 14:52
 */
@Service
public class StuBizImpl implements StuBiz {
@Autowired
private StuMapper stuMapper;
    @Override
    public int deleteByPrimaryKey(Integer sid) {
        return stuMapper.deleteByPrimaryKey(sid);
    }

    @Override
    public int insert(Stu record) {
        return stuMapper.insert(record);
    }

    @Override
    public int insertSelective(Stu record) {
        return stuMapper.insertSelective(record);
    }

    @Override
    public Stu selectByPrimaryKey(Integer sid) {
        return stuMapper.selectByPrimaryKey(sid);
    }

    @Override
    public int updateByPrimaryKeySelective(Stu record) {
        return stuMapper.updateByPrimaryKeySelective(record);
    }

    @Override
    public int updateByPrimaryKey(Stu record) {
        return stuMapper.updateByPrimaryKey(record);
    }

    @Override
    public List<Stu> ListPager(Stu stu, PageBean pageBean) {
        return stuMapper.selectByCon(stu);
    }

    @Override
    public List<Map> mapListPager(Stu stu, Object o) {
        return stuMapper.mapListPager(stu,o);
    }


}

package com.zlj.web;

import com.zlj.biz.StuBiz;
import com.zlj.model.Stu;
import com.zlj.util.PageBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletRequest;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
//@ResponseBody
//@Controller
@RestController  //@RestController=@ResponseBody+@Controller
@RequestMapping("/stu/json")
public class JsonController {
    @Autowired
    private StuBiz stuBiz;

    /**
     * 返回List<T>
     * @param req
     * @param stu
     * @return
     */
//    @ResponseBody
    @RequestMapping("/list")
    public List<Stu> list(HttpServletRequest req, Stu stu){
        PageBean pageBean = new PageBean();
        pageBean.setRequest(req);
        List<Stu> lst = this.stuBiz.ListPager(stu, pageBean);
        return lst;
    }

    /**
     * 返回T
     * @param req
     * @param stu
     * @return
     */
//    @ResponseBody
    @RequestMapping("/load")
    public Stu load(HttpServletRequest req, Stu stu){
        if(stu.getSid() != null){
            List<Stu> lst = this.stuBiz.ListPager(stu, null);
            return lst.get(0);
        }
        return null;
    }


    /**
     * 返回List<Map>
     * @param req
     * @param stu
     * @return
     */
//    @ResponseBody
    @RequestMapping("/mapList")
    public List<Map> mapList(HttpServletRequest req, Stu stu){
        PageBean pageBean = new PageBean();
        pageBean.setRequest(req);
        List<Map> lst = this.stuBiz.mapListPager(stu, pageBean);
        return lst;
    }

    /**
     * 返回Map
     * @param req
     * @param stu
     * @return
     */
//    @ResponseBody
    @RequestMapping("/mapLoad")
    public Map mapLoad(HttpServletRequest req, Stu stu){
        if(stu.getSid() != null){
            List<Map> lst = this.stuBiz.mapListPager(stu, null);
            return lst.get(0);
        }
        return null;
    }


//    @ResponseBody
    @RequestMapping("/all")
    public Map all(HttpServletRequest req, Stu stu){
        PageBean pageBean = new PageBean();
        pageBean.setRequest(req);
        List<Stu> lst = this.stuBiz.ListPager(stu, pageBean);
        Map map = new HashMap();
        map.put("lst",lst);
        map.put("pageBean",pageBean);
        return map;
    }

//    @ResponseBody  //返回单个字符串，而不是页面
    @RequestMapping("/jsonStr")
    public String jsonStr(HttpServletRequest req, Stu stu){
        System.out.println("333.....");
        return "stuEdit";
    }


}

@RestController=@ResponseBody+@Controller

2.统一异常处理

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。

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。

处理异常方式一演示（StuBizImpl的mapList方法加 stu=null; System.out.println(stu.getSame();--------jsonCotrollor的list方法加）System.out.println(1 / 0);），spring-mvc.xml配置，建一个error.jsp页面，分别报两个错

package com.zlj.biz.Impl;

import com.zlj.biz.StuBiz;
import com.zlj.mapper.StuMapper;
import com.zlj.model.Stu;
import com.zlj.util.PageBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Map;

/**
 * @author zlj
 * @create 2023-09-08 14:52
 */
@Service
public class StuBizImpl implements StuBiz {
@Autowired
private StuMapper stuMapper;
    @Override
    public int deleteByPrimaryKey(Integer sid) {
        return stuMapper.deleteByPrimaryKey(sid);
    }

    @Override
    public int insert(Stu record) {
        return stuMapper.insert(record);
    }

    @Override
    public int insertSelective(Stu record) {
        return stuMapper.insertSelective(record);
    }

    @Override
    public Stu selectByPrimaryKey(Integer sid) {
        return stuMapper.selectByPrimaryKey(sid);
    }

    @Override
    public int updateByPrimaryKeySelective(Stu record) {
        return stuMapper.updateByPrimaryKeySelective(record);
    }

    @Override
    public int updateByPrimaryKey(Stu record) {
        return stuMapper.updateByPrimaryKey(record);
    }

    @Override
    public List<Stu> ListPager(Stu stu, PageBean pageBean) {
        return stuMapper.selectByCon(stu);
    }

    @Override
    public List<Map> mapListPager(Stu stu, Object o) {
        stu=null;
        System.out.println(stu.getSame());
        return stuMapper.mapListPager(stu,o);
    }


}

package com.zlj.web;

import com.zlj.biz.StuBiz;
import com.zlj.model.Stu;
import com.zlj.util.PageBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletRequest;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
//@ResponseBody
//@Controller
@RestController  //@RestController=@ResponseBody+@Controller
@RequestMapping("/stu/json")
public class JsonController {
    @Autowired
    private StuBiz stuBiz;

    /**
     * 返回List<T>
     * @param req
     * @param stu
     * @return
     */
//    @ResponseBody
    @RequestMapping("/list")
    public List<Stu> list(HttpServletRequest req, Stu stu){
        PageBean pageBean = new PageBean();
        pageBean.setRequest(req);
        List<Stu> lst = this.stuBiz.ListPager(stu, pageBean);
        System.out.println(1 / 0);
        return lst;
    }

    /**
     * 返回T
     * @param req
     * @param stu
     * @return
     */
//    @ResponseBody
    @RequestMapping("/load")
    public Stu load(HttpServletRequest req, Stu stu){
        if(stu.getSid() != null){
            List<Stu> lst = this.stuBiz.ListPager(stu, null);
            return lst.get(0);
        }
        return null;
    }


    /**
     * 返回List<Map>
     * @param req
     * @param stu
     * @return
     */
//    @ResponseBody
    @RequestMapping("/mapList")
    public List<Map> mapList(HttpServletRequest req, Stu stu){
        PageBean pageBean = new PageBean();
        pageBean.setRequest(req);
        List<Map> lst = this.stuBiz.mapListPager(stu, pageBean);
        return lst;
    }

    /**
     * 返回Map
     * @param req
     * @param stu
     * @return
     */
//    @ResponseBody
    @RequestMapping("/mapLoad")
    public Map mapLoad(HttpServletRequest req, Stu stu){
        if(stu.getSid() != null){
            List<Map> lst = this.stuBiz.mapListPager(stu, null);
            return lst.get(0);
        }
        return null;
    }


//    @ResponseBody
    @RequestMapping("/all")
    public Map all(HttpServletRequest req, Stu stu){
        PageBean pageBean = new PageBean();
        pageBean.setRequest(req);
        List<Stu> lst = this.stuBiz.ListPager(stu, pageBean);
        Map map = new HashMap();
        map.put("lst",lst);
        map.put("pageBean",pageBean);
        return map;
    }

//    @ResponseBody  //返回单个字符串，而不是页面
    @RequestMapping("/jsonStr")
    public String jsonStr(HttpServletRequest req, Stu stu){
        System.out.println("333.....");
        return "stuEdit";
    }


}

//spring-mvc.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
   <!--1) 扫描com.zking.zf及子子孙孙包下的控制器(扫描范围过大，耗时)-->
    <context:component-scan base-package="com.zlj"/>

    <!--2) 此标签默认注册DefaultAnnotationHandlerMapping和AnnotationMethodHandlerAdapter -->
    <mvc:annotation-driven />

    <!--3) 创建ViewResolver视图解析器 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!-- viewClass需要在pom中引入两个包：standard.jar and jstl.jar -->
        <property name="viewClass"
                  value="org.springframework.web.servlet.view.JstlView"></property>
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--4) 单独处理图片、样式、js等资源 -->
<!--     <mvc:resources location="/css/" mapping="/css/**"/>-->
<!--     <mvc:resources location="/js/" mapping="/js/**"/>-->
<!--     <mvc:resources location="WEB-INF/images/" mapping="/images/**"/>  -->
    <mvc:resources location="/static/" mapping="/static/**"/>

    <!--    处理文件上传下载问题-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- 必须和用户JSP 的pageEncoding属性一致，以便正确解析表单的内容 -->
        <property name="defaultEncoding" value="UTF-8"></property>
        <!-- 文件最大大小(字节) 1024*1024*50=50M-->
        <property name="maxUploadSize" value="52428800"></property>
        <!--resolveLazily属性启用是为了推迟文件解析，以便捕获文件大小异常-->
        <property name="resolveLazily" value="true"/>
    </bean>

<!--    配置拦截器-->
    <mvc:interceptors>
        <bean class="com.zlj.interceptor.LoginInterceptor"></bean>
    </mvc:interceptors>

<!--单拦截器-->
<!--    <mvc:interceptors>-->
<!--        <bean class="com.zlj.interceptor.OneInterceptor"></bean>-->
<!--    </mvc:interceptors>-->

<!--    <mvc:interceptors>-->
<!--        &lt;!&ndash;2) 多拦截器（拦截器链）&ndash;&gt;-->
<!--        <mvc:interceptor>-->
<!--            <mvc:mapping path="/**"/>-->
<!--            <bean class="com.zlj.interceptor.OneInterceptor"/>-->
<!--        </mvc:interceptor>-->
<!--        <mvc:interceptor>-->
<!--            <mvc:mapping path="/stu/**"/>-->
<!--            <bean class="com.zlj.interceptor.TwoInterceptor"/>-->
<!--        </mvc:interceptor>-->
<!--    </mvc:interceptors>-->

    <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>



    <!-- 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>

    <!--    处理controller层发送请求到biz，会经过切面拦截处理-->
    <aop:aspectj-autoproxy/>
</beans>

package com.zlj.exception;

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);
    }
}

处理方式二，GobalHandler

package com.zlj.component;

import com.zlj.exception.GlobalException;
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;

@Component
public class GlobalExceptionHandler implements HandlerExceptionResolver {
    @Override
    public ModelAndView resolveException(HttpServletRequest httpServletRequest,
                                         HttpServletResponse httpServletResponse,
                                         Object o, Exception e) {
        ModelAndView mv = new ModelAndView();
        mv.setViewName("error");//WEB-INF/jsp/error.jsp
        if (e instanceof GlobalException){
            GlobalException globalException = (GlobalException) e;
            mv.addObject("ex",globalException.getMessage());
            mv.addObject("msg","全局异常....");
        }else if (e instanceof RuntimeException){
            RuntimeException runtimeException = (RuntimeException) e;
            mv.addObject("ex",runtimeException.getMessage());
            mv.addObject("msg","运行时异常....");
        }else{
            mv.addObject("ex",e.getMessage());
            mv.addObject("msg","其他异常....");
        }
        return mv;
    }
}

注：@Component注释后会没有效果

<%--
  Created by IntelliJ IDEA.
  User: 朱
  Date: 2023/9/13
  Time: 15:31
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
错误信息界面。。。
<hr>
${ex}
</hr>
<hr>
${msg}
</hr>
</body>
</html>

方式三

package com.zlj.component;

import com.zlj.exception.GlobalException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.HashMap;
import java.util.Map;

@ControllerAdvice
public class GlobalExceptionResolver {

//    跳转错误页面
//    @ExceptionHandler
//    public ModelAndView handler(Exception e){
//        ModelAndView mv = new ModelAndView();
//        mv.setViewName("error");
//        if (e instanceof GlobalException){
//            GlobalException globalException = (GlobalException) e;
//            mv.addObject("ex",globalException.getMessage());
//            mv.addObject("msg","全局异常....");
//        }else if (e instanceof RuntimeException){
//            RuntimeException runtimeException = (RuntimeException) e;
//            mv.addObject("ex",runtimeException.getMessage());
//            mv.addObject("msg","运行时异常....");
//        }
//        return mv;
//    }

// 返回错误json数据
    @ResponseBody
    @ExceptionHandler
    public Map handler(Exception e){
        Map map = new HashMap();
        if (e instanceof GlobalException){
            GlobalException globalException = (GlobalException) e;
            map.put("ex",globalException.getMessage());
            map.put("msg","全局异常....");
        }else if (e instanceof RuntimeException){
            RuntimeException runtimeException = (RuntimeException) e;
            map.put("ex",runtimeException.getMessage());
            map.put("msg","运行时异常....");
        }else {
            map.put("ex",e.getMessage());
            map.put("msg","其它异常....");
        }
        return map;
    }
}

package com.zlj.component;

import com.zlj.exception.GlobalException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.ModelAndView;

@ControllerAdvice
public class GlobalExceptionResolver {

//    跳转错误页面
    @ExceptionHandler
    public ModelAndView handler(Exception e){
        ModelAndView mv = new ModelAndView();
        mv.setViewName("error");
        if (e instanceof GlobalException){
            GlobalException globalException = (GlobalException) e;
            mv.addObject("ex",globalException.getMessage());
            mv.addObject("msg","全局异常....");
        }else if (e instanceof RuntimeException){
            RuntimeException runtimeException = (RuntimeException) e;
            mv.addObject("ex",runtimeException.getMessage());
            mv.addObject("msg","运行时异常....");
        }
        return mv;
    }

// 返回错误json数据
//    @ResponseBody
//    @ExceptionHandler
//    public Map handler(Exception e){
//        Map map = new HashMap();
//        if (e instanceof GlobalException){
//            GlobalException globalException = (GlobalException) e;
//            map.put("ex",globalException.getMessage());
//            map.put("msg","全局异常....");
//        }else if (e instanceof RuntimeException){
//            RuntimeException runtimeException = (RuntimeException) e;
//            map.put("ex",runtimeException.getMessage());
//            map.put("msg","运行时异常....");
//        }else {
//            map.put("ex",e.getMessage());
//            map.put("msg","其它异常....");
//        }
//        return map;
//    }
}

SpringMVC之JSON返回&异常处理机制

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