mybatis的使用及源码分析(五) mybatis自定义typeHandler
当我们在javabean中自定义了枚举类型或者其它某个类型，但是在数据库中存储时往往需要转换成数据库对应的类型，并且在从数据库中取出来时也需要将数据库类型转换为javabean中的对应类型。比如：javabean中字段类型为Date，数据库中存储的是varchar类型；javabean中字段类型是Enum，数据库中存储的是String或者Integer。
因为有大量类似数据的转换，手动转换类型进行存储和查询已经过于麻烦。MyBatis为我们提供了解决办法：TypeHandler类型处理器。
MyBatis 内置的 TypeHandler
在 MyBatis 常见内的内置Ty’peHandler
BooleanTypeHandler：用于 java 类型 boolean，jdbc 类型 bit、boolean
ByteTypeHandler：用于 java 类型 byte，jdbc 类型 TINYINT
ShortTypeHandler：用于 java 类型 short，jdbc 类型 SMALLINT
IntegerTypeHandler：用于 INTEGER 类型
LongTypeHandler：用于 long 类型
FloatTypeHandler：用于 FLOAT 类型
DoubleTypeHandler：用于 double 类型
StringTypeHandler：用于 java 类型 string，jdbc 类型 CHAR、VARCHAR
ArrayTypeHandler：用于 jdbc 类型 ARRAY
BigDecimalTypeHandler：用于 java 类型 BigDecimal，jdbc 类型 REAL、DECIMAL、NUMERIC
DateTypeHandler：用于 java 类型 Date，jdbc 类型 TIMESTAMP
DateOnlyTypeHandler：用于 java 类型 Date，jdbc 类型 DATE
TimeOnlyTypeHandler：用于 java 类型 Date，jdbc 类型 TIME
对于常见的 Enum 类型，内置了 EnumTypeHandler 进行 Enum 名称的转换和 EnumOrdinalTypeHandler 进行 Enum 序数的转换。这两个类型处理器没有在 TypeHandlerRegistry 中注册，如果需要使用必须手动配置。
自定义一个TypeHandler:
本项目搭建源码：https://github.com/zhuquanwen/mybatis-learn/releases/tag/for-typehandler
搭建过程：
在https://blog.csdn.net/u011943534/article/details/104732289文章基础上搭建，有些过程不详细描述.
1、导入本文测试使用的sql脚本
/*
Navicat MySQL Data Transfer
Source Server : localhost
Source Server Version : 50722
Source Host : localhost:3306
Source Database : mybatis_learn
Target Server Type : MYSQL
Target Server Version : 50722
File Encoding : 65001
Date: 2020-03-16 23:06:58
*/
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for bird
-- ----------------------------
DROP TABLE IF EXISTS `bird`;
CREATE TABLE `bird` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(80) DEFAULT NULL,
`sex` smallint(6) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4;
-- ----------------------------
-- Records of bird
-- ----------------------------
INSERT INTO `bird` VALUES ('1', '小黄', '1');
INSERT INTO `bird` VALUES ('2', '小绿', '0');
INSERT INTO `bird` VALUES ('3', '小黑', '1');
2、配置generator插件，之后运行com.learn.zqw.generator.Generator的主函数将bird表自动生成实体和mapper
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
"http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
<!-- context指定环境 -->
<context id="MyGererator" targetRuntime="MyBatis3">
<!-- 这个标签可以去掉各类元素生成的注释，默认是全部生成的 -->
<commentGenerator>
<!-- 去掉注释 -->
<property name="suppressAllComments" value="true"/>
<!-- 去掉时间戳 -->
<property name="suppressDate" value="true"/>
</commentGenerator>
<!-- 数据库连接信息 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/mybatis_learn?useUnicode=true&characterEncoding=utf8"
userId="root"
password="root">
</jdbcConnection>
<!-- JAVA JDBC数据类型转换,可以参照官方文档 -->
<javaTypeResolver >
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<!-- javaModelGenerator javaBean配置
targetPackage 输入包名 输出路径
targetProject 输出项目位置 -->
<javaModelGenerator targetPackage="com.learn.zqw.generator.domain" targetProject="src/main/java">
<!-- enableSubPackages 是否开启子包名称 是否在包名后边加上scheme名称 -->
<property name="enableSubPackages" value="false" />
<!-- 在Set方法中加入.trim -->
<property name="trimStrings" value="true" />
</javaModelGenerator>
<!-- 映射文件mapper.xml配置 -->
<sqlMapGenerator targetPackage="com.learn.zqw.generator.mapper" targetProject="src/main/java">
<property name="enableSubPackages" value="false" />
</sqlMapGenerator>
<!-- 动态代理类接口，和mapper.xml在要同一个路径 -->
<javaClientGenerator type="XMLMAPPER" targetPackage="com.learn.zqw.generator.mapper" targetProject="src/main/java">
<property name="enableSubPackages" value="true" />
</javaClientGenerator>
<!-- 数据表 根据数据库中的表来生成 -->
<!--<table tableName="student"/>-->
<table tableName="bird"/>
<!-- 数据表更详细的属性参见官方文档，也可参照https://www.jianshu.com/p/e09d2370b796，里注释掉-->
<!-- <table schema="DB2ADMIN" tableName="ALLTYPES" domainObjectName="Customer" >
<property name="useActualColumnNames" value="true"/>
<generatedKey column="ID" sqlStatement="DB2" identity="true" />
<columnOverride column="DATE_FIELD" property="startDate" />
<ignoreColumn column="FRED" />
<columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" />
</table> -->
</context>
</generatorConfiguration>
3、定义性别的枚举，并将Bird实体的sex字段改为此枚举类型
package com.learn.zqw.generator.domain;
/**
* //TODO
*
* @author zhuquanwen
* @vesion 1.0
* @date 2020/3/16 22:29
* @since jdk1.8
*/
public enum SexEnum {
MALE(0, "雄性"),
FEMALE(1, "雌性");
public int val;
public String label;
public int getVal() {
return val;
}
public String getLabel() {
return label;
}
SexEnum(int val, String label) {
this.val = val;
this.label = label;
}
}
package com.learn.zqw.generator.domain;
import lombok.Data;
@Data
public class Bird {
private Integer id;
private String name;
private SexEnum sex = SexEnum.MALE;
}
4、编写SexEnum转换的SexEnumTypeHandler
package com.learn.zqw.handler;
import com.learn.zqw.generator.domain.SexEnum;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
* //TODO
*
* @author zhuquanwen
* @vesion 1.0
* @date 2020/3/16 22:04
* @since jdk1.8
*/
@MappedTypes(value = {SexEnum.class})
@MappedJdbcTypes(JdbcType.SMALLINT)
public class SexEnumTypeHandler extends BaseTypeHandler<SexEnum> {
@Override
public void setNonNullParameter(PreparedStatement ps, int i, SexEnum parameter, JdbcType jdbcType) throws SQLException {
ps.setInt(i, parameter.getVal());
}
@Override
public SexEnum getNullableResult(ResultSet rs, String columnName) throws SQLException {
int val = rs.getInt(columnName);
return convert(val);
}
@Override
public SexEnum getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
int val = rs.getInt(columnIndex);
return convert(val);
}
@Override
public SexEnum getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
int val = cs.getInt(columnIndex);
return convert(val);
}
private SexEnum convert(int val) {
SexEnum[] objs = SexEnum.values();
for (SexEnum em : objs) {
if (em.getVal() == val) {
return em;
}
}
return null;
}
}
5、在SqlMapConfig.xml中注册此SexEnumTypeHandler与BirdMapper.xml
<configuration>
<typeHandlers>
<typeHandler handler="com.learn.zqw.handler.SexEnumTypeHandler"
javaType="com.learn.zqw.generator.domain.SexEnum"
jdbcType="SMALLINT"/>
typeHandlers>
<environments default="mysql">
<environment id="mysql">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis_learn?useUnicode=true&characterEncoding=utf8"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
dataSource>
environment>
environments>
<mappers>
<mapper resource="com/learn/zqw/IUserMapper.xml" />
<mapper resource="com/learn/zqw/generator/mapper/StudentMapper.xml" />
<mapper resource="com/learn/zqw/generator/mapper/BirdMapper.xml" />
<package name="com.learn.zqw.sqlannotation.mapper"/>
mappers>
configuration>
6、修改自动生成的BirdMapper,将sex字段的定义都加上typeHandler
<mapper namespace="com.learn.zqw.generator.mapper.BirdMapper">
<resultMap id="BaseResultMap" type="com.learn.zqw.generator.domain.Bird">
<id column="id" jdbcType="INTEGER" property="id" />
<result column="name" jdbcType="VARCHAR" property="name" />
<result column="sex" jdbcType="SMALLINT" property="sex" typeHandler="com.learn.zqw.handler.SexEnumTypeHandler" />
resultMap>
<sql id="Example_Where_Clause">
<where>
<foreach collection="oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
foreach>
when>
choose>
foreach>
trim>
if>
foreach>
where>
sql>
<sql id="Update_By_Example_Where_Clause">
<where>
<foreach collection="example.oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
foreach>
when>
choose>
foreach>
trim>
if>
foreach>
where>
sql>
<sql id="Base_Column_List">
id, name, sex
sql>
<select id="selectByExample" parameterType="com.learn.zqw.generator.domain.BirdExample" resultMap="BaseResultMap">
select
<if test="distinct">
distinct
if>
<include refid="Base_Column_List" />
from bird
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
if>
<if test="orderByClause != null">
order by ${orderByClause}
if>
select>
<select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from bird
where id = #{id,jdbcType=INTEGER}
select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
delete from bird
where id = #{id,jdbcType=INTEGER}
delete>
<delete id="deleteByExample" parameterType="com.learn.zqw.generator.domain.BirdExample">
delete from bird
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
if>
delete>
<insert id="insert" parameterType="com.learn.zqw.generator.domain.Bird">
insert into bird (id, name, sex
)
values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR},
#{sex,jdbcType=SMALLINT, typeHandler=com.learn.zqw.handler.SexEnumTypeHandler}
)
insert>
<insert id="insertSelective" parameterType="com.learn.zqw.generator.domain.Bird">
insert into bird
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="id != null">
id,
if>
<if test="name != null">
name,
if>
<if test="sex != null">
sex,
if>
trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="id != null">
#{id,jdbcType=INTEGER},
if>
<if test="name != null">
#{name,jdbcType=VARCHAR},
if>
<if test="sex != null">
#{sex,jdbcType=SMALLINT},
if>
trim>
insert>
<select id="countByExample" parameterType="com.learn.zqw.generator.domain.BirdExample" resultType="java.lang.Long">
select count(*) from bird
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
if>
select>
<update id="updateByExampleSelective" parameterType="map">
update bird
<set>
<if test="record.id != null">
id = #{record.id,jdbcType=INTEGER},
if>
<if test="record.name != null">
name = #{record.name,jdbcType=VARCHAR},
if>
<if test="record.sex != null">
sex = #{record.sex,jdbcType=SMALLINT, typeHandler=com.learn.zqw.handler.SexEnumTypeHandler},
if>
set>
<if test="_parameter != null">
<include refid="Update_By_Example_Where_Clause" />
if>
update>
<update id="updateByExample" parameterType="map">
update bird
set id = #{record.id,jdbcType=INTEGER},
name = #{record.name,jdbcType=VARCHAR},
sex = #{record.sex,jdbcType=SMALLINT, typeHandler=com.learn.zqw.handler.SexEnumTypeHandler}
<if test="_parameter != null">
<include refid="Update_By_Example_Where_Clause" />
if>
update>
<update id="updateByPrimaryKeySelective" parameterType="com.learn.zqw.generator.domain.Bird">
update bird
<set>
<if test="name != null">
name = #{name,jdbcType=VARCHAR},
if>
<if test="sex != null">
sex = #{sex,jdbcType=SMALLINT, typeHandler=com.learn.zqw.handler.SexEnumTypeHandler},
if>
set>
where id = #{id,jdbcType=INTEGER}
update>
<update id="updateByPrimaryKey" parameterType="com.learn.zqw.generator.domain.Bird">
update bird
set name = #{name,jdbcType=VARCHAR},
sex = #{sex,jdbcType=SMALLINT, typeHandler=com.learn.zqw.handler.SexEnumTypeHandler}
where id = #{id,jdbcType=INTEGER}
update>
mapper>
7、编写单元测试
package com.learn.zqw;
import com.learn.zqw.generator.domain.Bird;
import com.learn.zqw.generator.domain.BirdExample;
import com.learn.zqw.generator.domain.SexEnum;
import com.learn.zqw.generator.mapper.BirdMapper;
import lombok.Cleanup;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
/**
*
* @author zhuquanwen
* @vesion 1.0
* @date 2020/3/16 22:14
* @since jdk1.8
*/
@RunWith(JUnit4.class)
public class TypeHandlerTests {
/**
* 测试查询所有
* */
@Test
public void test() throws IOException {
@Cleanup InputStream in = Resources.getResourceAsStream ("SqlMapConfig.xml");
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
SqlSession session = factory.openSession();
BirdMapper mapper = session.getMapper(BirdMapper.class);
BirdExample birdExample = new BirdExample();
List<Bird> birds = mapper.selectByExample(birdExample);
Assert.assertNotNull(birds);
if (birds != null) {
birds.forEach(System.out::println);
}
Bird bird = new Bird();
bird.setName("小紫");
bird.setSex(SexEnum.MALE);
mapper.insert(bird);
session.commit();
}
}