mybatis-枚举类型的typeHandler

Posted 2020-10-10 寻找风口的猪

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了mybatis-枚举类型的typeHandler相关的知识，希望对你有一定的参考价值。

MyBatis内部提供了两个转化枚举类型的typeHandler给我们使用。

org.apache.ibatis.type.EnumTypeHandler 是使用枚举字符串名称作为参数传递的
org.apache.ibatis.type.EnumOrdinalTypeHandler 是使用整数下标作为参数传递的

数据库脚CREATE TABLE `user` (

  `id` int(11) NOT NULL AUTO_INCREMENT,
  `userName` varchar(50) DEFAULT NULL,
  `gender` int(11) DEFAULT NULL, --对应Gender枚举类
  `hobby` varchar(255) DEFAULT NULL, --对用Hobby枚举类
  `member` int(11) DEFAULT NULL, --对应Member枚举类
  `userAge` int(11) DEFAULT NULL,
  `userAddress` varchar(200) DEFAULT NULL,
  `reg_time` varchar(200) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;

创建三个枚举类Gender、Hobby、Member

package com.yihaomen.mybatis.enums;

public enum  Gender {

    MALE(1, "男性"), FEMALE(2, "女性");
    private int code;
    private String name;

    Gender(int code, String name) {
        this.code = code;
        this.name = name;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public static Gender getGender(int code) {
        for(Gender gender : Gender.values()) {
            if(gender.getCode() == code) {
                return gender;
            }
        }
        return null;
    }

}

package com.yihaomen.mybatis.enums;

public enum Hobby {
    FOOTBALL(1,"足球"), BASKETBALL(2, "篮球");
    private int code;
    private String name;

    Hobby(int code, String name) {
        this.code = code;
        this.name = name;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public static Hobby getHobby(int code) {
        for(Hobby h : Hobby.values()) {
            if(h.getCode() == code) {
                return h;
            }
        }
        return null;
    }

    public void setName(String name) {
        this.name = name;
    }
}

package com.yihaomen.mybatis.enums;

public enum Member {
    FATHER(1,"爸爸"), MOTHER(2,"妈妈");
    private int code;
    private String name;

    Member(int code, String name) {
        this.code = code;
        this.name = name;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public static Member getMember(int code) {
        for(Member member : Member.values()) {
            if(member.getCode() == code) {
                return member;
            }
        }
        return null;
    }
}

写model层

package com.yihaomen.mybatis.model;

import com.yihaomen.mybatis.enums.Gender;
import com.yihaomen.mybatis.enums.Hobby;

import java.util.Date;

public class User {
    private int id;
    private String userName;
    private String userAge;
    private Gender gender;
    private Member member;
    private Hobby hobby;
    private String userAddress;
    private Date regTime;
    
    setters()&getters()...    
}

自定义typeHandler

package com.yihaomen.mybatis.type;

import com.yihaomen.mybatis.enums.Member;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.TypeHandler;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class MyMemberTypeHandler implements TypeHandler<Member> {
    public void setParameter(PreparedStatement ps, int i, Member parameter, JdbcType jdbcType) throws SQLException {
        ps.setInt(i, parameter.getCode());
    }

    public Member getResult(ResultSet rs, String columnName) throws SQLException {
        int code = rs.getInt(columnName);
        return Member.getMember(code);
    }

    public Member getResult(ResultSet rs, int columnIndex) throws SQLException {
        int code = rs.getInt(columnIndex);
        return Member.getMember(code);
    }

    public Member getResult(CallableStatement cs, int columnIndex) throws SQLException {
        int code = cs.getInt(columnIndex);
        return Member.getMember(code);
    }
}

写DAO层

User.xml

<?xml version="1.0" encoding="UTF-8" ?>
<resultMap id="resultListUser" type="User">
        <id column="id" property="id" />
        <result column="userName" property="userName" />
        <result column="userAge" property="userAge" />
        <!---->
        <result column="gender" property="gender" typeHandler="org.apache.ibatis.type.EnumOrdinalTypeHandler"/>
        <result column="hobby" property="hobby" typeHandler="org.apache.ibatis.type.EnumTypeHandler"/>
　　　　 <result column="member" property="member" typeHandler="com.yihaomen.mybatis.type.MyMemberTypeHandler"/><!--自定义枚举typeHandler-->
        <result column="userAddress" property="userAddress" /> <result column="reg_time" property="regTime" javaType="java.util.Date" jdbcType="VARCHAR" typeHandler="com.yihaomen.mybatis.type.MyDateTypeHandler"/> </resultMap> <select id="selectUserById2" parameterType="long" resultMap="resultListUser"> select userName, gender, hobby from user where id = #{id}</select> <insert id="addUser2" parameterType="User" useGeneratedKeys="true" keyProperty="id"> INSERT INTO user(userName, userAge, gender, hobby, userAddress, reg_time) VALUES(#{userName},#{userAge},#{gender},#{hobby},#{userAddress}, #{regTime,javaType=Date,jdbcType=VARCHAR,typeHandler=com.yihaomen.mybatis.type.MyDateTypeHandler}) </insert>

UserMapper

package com.yihaomen.mybatis.dao;

import com.yihaomen.mybatis.model.User;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface UserMapper {
    public List<User> selectUserById2(Long id);
    public int addUser2(User user);
}

在configuration.xml注册typeHandler

<typeHandlers>
        <typeHandler handler="com.yihaomen.mybatis.type.MyDateTypeHandler" />
        <typeHandler handler="org.apache.ibatis.type.EnumOrdinalTypeHandler"
                     javaType="com.yihaomen.mybatis.enums.Gender" />
        <typeHandler handler="org.apache.ibatis.type.EnumTypeHandler" 
                     javaType="com.yihaomen.mybatis.enums.Hobby"/>

　　　　 <typeHandler handler="com.yihaomen.mybatis.type.MyMemberTypeHandler"
        　　　　      javaType="com.yihaomen.mybatis.enums.Member"/>
</typeHandlers>

测试一下：

package user;

import com.yihaomen.mybatis.dao.UserMapper;
import com.yihaomen.mybatis.enums.Gender;
import com.yihaomen.mybatis.enums.Hobby;
import com.yihaomen.mybatis.enums.Member;
import com.yihaomen.mybatis.model.User;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.Date;
import java.util.List;

/**
 *   
 *  @ProjectName: springmvc-mybatis 
 *  @Description:
 */
public class TestEnumUser extends BaseTest{
    public static void main(String[] args) {
//        testAddEnum();
        testGetEnumUser();
    }

    /**
     * 添加
     */
    public static void testAddEnum() {
        SqlSession sqlSession = null;
        try {
            SqlSessionFactory sqlSessionFactory = getSession();
            sqlSession = sqlSessionFactory.openSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            User user = new User();
            user.setUserName("小明");
            user.setGender(Gender.MALE);
            user.setHobby(Hobby.FOOTBALL);
            user.setMember(Member.FATHER);
            user.setRegTime(new Date());
            user.setUserAddress("地球");
            user.setUserAge("22");
            int result = mapper.addUser2(user);
            System.out.println(result);
            sqlSession.commit();
        } catch (Exception e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally {
            if(sqlSession != null) {
                sqlSession.close();
            }
        }
    }

    /**
     * select
     */
    public static void testGetEnumUser() {
        SqlSession sqlSession = null;
        try {
            SqlSessionFactory sqlSessionFactory = getSession();
            sqlSession = sqlSessionFactory.openSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            List<User> users = mapper.selectUserById2(11L);
            for(User u : users) {
                System.out.println(u.getGender());
                System.out.println(u.getHobby());
                System.out.println(u.getMember());
            }
            sqlSession.commit();
        } catch (Exception e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally {
            if(sqlSession != null) {
                sqlSession.close();
            }
        }
    }
}

https://gitee.com/huayicompany/springmvc-mybatis.git

参考文献:

[1] 杨开振著，《深入浅出MyBatis技术原理与实战》，电子工业出版社，2016.09

以上是关于mybatis-枚举类型的typeHandler的主要内容，如果未能解决你的问题，请参考以下文章

mybatis扩展之自定义类型处理器处理枚举类型

MyBatis里字段到枚举类的映射

Springboot整合Mybatis使用TypeHandler来转换数据库中的数据

mybatis之typehandles

MyBatis使用自定义TypeHandler转换类型