MyBatis typeHandler接口的定义和使用

<!-- mybatis依赖 -->
<dependency>  
    <groupId>org.mybatis.spring.boot</groupId>  
    <artifactId>mybatis-spring-boot-starter</artifactId>  
    <version>2.0.0</version>  
</dependency>
<!-- 数据库连接池 -->
<dependency>  
    <groupId>com.alibaba</groupId>  
    <artifactId>druid</artifactId>  
    <version>1.1.10</version>  
</dependency>
<!-- mysql数据库连接 -->
<dependency>  
    <groupId>mysql</groupId>  
    <artifactId>mysql-connector-java</artifactId>  
    <version>5.1.48</version>
	<!--此仅参考,版本根据需要而定-->
</dependency>

package com.xx.yy.zz.model; 
import java.util.List;
public class UserProduct {
	private String userName;
	private String userCode
	//DB字段以JSON格式保存:["产品名1(产品代码1)","产品名2(产品代码2)",...]
	private List<String> likeProducts = new ArraryList<String>();
	//...other... 
	//...setter/getter省略...
}

package com.xx.yy.zz.orm; 
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.List;
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 com.alibaba.fastjson.JSONObject; //需要fastjson的jar包支持
@MappedTypes(List.class) //映射的Java数据类型
@MappedJdbcTypes(JdbcType.VARCHAR)  //映射的JDBC数据类型
public class MyListTypeHandler extends BaseTypeHandler<List<String>>{
	//List列表中如果为其它对象xxJavaBean则把String换为目标对象	
	//重写mybatis设置参数的方法
	@Override
	public void setNonNullParameter(PreparedStatement ps,int i, List<String> param,
		JdbcType jdbcType) throws SQLException {
		ps.setString(i, JSONObject.toJSONString(param));
	}
	//重写mybatis获取字段字符串型内容到Bean类List变量的方法
	@Override
	public List<String> getNullableResult(ResultSet rs, String columnName)
		throws SQLException{
		String tempJson = rs.getString(columnName);
		if (null != tempJson && !tempJson.trim().isEmpty()){
			return JSONObject.parseArray(tempJson,String.class);
		}
		return null;
	}
	@Override
	public List<String> getNullableResult(ResultSet rs, int columnIndex)
		throws SQLException{
		String tempJson = rs.getString(columnIndex);
		if (null != tempJson && !tempJson.trim().isEmpty()){
			return JSONObject.parseArray(tempJson,String.class);
		}
		return null;
	}
	@Override
	public List<String> getNullableResult(CallableStatement cs, int columnIndex)
		throws SQLException{
		String tempJson = cs.getString(columnName);
		if (null != tempJson && !tempJson.trim().isEmpty()){
			return JSONObject.parseArray(tempJson,String.class);
		}
		return null;
	}
}

package com.xx.yy.zz.dao;
import com.xx.yy.zz.model.UserProduct;
public interface UserProductDao {
	int insertRecord(UserProduct record);
	int updateRecord(UserProduct record);
	//...more code...
}

<mapper namespace="com.xx.yy.zz.dao.UserProductDao" >
	<resultMap id="resultMap" type="com.xx.yy.zz.model.Product">
		<id column="id" property="id" jdbcType="Decimal">
		<result column="likeProdcts" property="likeProdcts" jdbcType="varchar"
			typeHandler="com.xx.yy.zz.orm.MyListTypeHandler">
		<!-- ...other result... -->
	</resultMap>
</mapper>
<!-- 新增 -->
<insert id="insertRecord" parameterType="UserProduct">
	insert into xxTable
	<trim prefix="(" suffix=")" suffixOverride=",">
		<if test="userName != null">
		userName,
		</if>
		<!-- ...other... -->
		<if test="likeProdcts != null">
		likeProdcts,
		</if>		
	</trim>
	<trim prefix=" values (" suffix=")" suffixOverride=",">
		<if test="userName != null">
		#{userName,jdbcType=varchar},
		</if
		<!-- ...other... -->
		<if test="likeProdcts != null">
		#{likeProdcts,jdbcType=varchar,typeHandler=com.xx.yy.zz.orm.MyListTypeHandler},
		</if>
	</trim>
</insert>
<!-- 更新 -->
<update id="updateRecord" parameterType="UserProduct">
	update xxTable 
	<set>
		<if test="likeProdcts != null">
		#{likeProdcts,jdbcType=varchar,typeHandler=com.xx.yy.zz.orm.MyListTypeHandler},
		</if>
		<!-- ...other... -->
	</set>
	where id = #{id,jdbcType=decimal}
</update>