Mybatis基础（四）编写自定义类型处理器

自定义类型处理器

1.首先创建数据库，并创建如下图的表：

2.创建一个普通的java项目，并在项目的Src目录下创建一个文件夹libs（用来存放mybatis和MySQL的驱动包），如图：**

然后选中这两个jar包，右键，选中Build path,点击add。。。。，然后就是下面这个样子了：

3.创建自定义类型处理器类

package converter;

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

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;

public class BooleanAndIntConverter extends BaseTypeHandler<Boolean> {
    
    
	/*
	 * java类型（boolean）--》jdbc类型（int）
	 * @param ps:	当前的PrepareStatement对象
	 * @param i: 	当前参数的位置
	 * @param parameter： 当前参数值
	 */

	@Override
	public Boolean getNullableResult(ResultSet rs, String i) throws SQLException {
    
    
		int sexNum=rs.getInt(i);
		if(sexNum==1) {
    
    
			return true;
		}else {
    
    
			return false;
		}
	}

	@Override
	public Boolean getNullableResult(ResultSet arg0, int arg1) throws SQLException {
    
    
		int sexNum=arg0.getInt(arg1);
		if(sexNum==1) {
    
    
			return true;
		}else {
    
    
			return false;
		}
	}

	@Override
	public Boolean getNullableResult(CallableStatement arg0, int arg1) throws SQLException {
    
    
		int sexNum=arg0.getInt(arg1);
		if(sexNum==1) {
    
    
			return true;
		}else {
    
    
			return false;
		}
	}

	@Override
	public void setNonNullParameter(PreparedStatement ps, int i, Boolean p, JdbcType arg3) throws SQLException {
    
    
		/*
		 * 如果Java类型的parameter=true，则数据库jdbc转换为1,反之为0
		 */
		if(p) {
    
    
			ps.setInt(i, 1);
		}else {
    
    
			ps.setInt(i,0);
		}
		
	}

}

4.配置自定义类型处理器，在Mybatis配置文件conf.xml中配置：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!-- 这里要写一个引用db.properties的配置文件 -->
		<properties resource="db.properties"/>
  <!--配置自定义类型处理器-->
<typeHandlers>
    	<typeHandler handler="converter.BooleanAndIntConverter" javaType="java.lang.Boolean" jdbcType="INTEGER"/>   	
    </typeHandlers>
   


    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="${driver}" />
                <property name="url" value="${url}" />
                <property name="username" value="${username}" />
                <property name="password" value="${password}" />
            </dataSource>
            
        </environment>
    </environments>
  <mappers>
        <mapper resource="dao/mapper.xml"/>
    </mappers>
    
</configuration>

5.创建db.properties：

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC
username=root
password=666666

6.创建实体类

package entity;

public class Student {
    
    
	private int sn;
	private String sname;
	private boolean ssex;
	public int getSn() {
    
    
		return sn;
	}
	public void setSn(int sn) {
    
    
		this.sn = sn;
	}
	public String getsname() {
    
    
		return sname;
	}
	public void setsname(String sname) {
    
    
		this.sname = sname;
	}
	public boolean getSsex() {
    
    
		return ssex;
	}
	public void setSsex(boolean ssex) {
    
    
		this.ssex = ssex;
	}
	
}

7.MQL映射文件mapper.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="dao.StudentDao">

<select id="converter" parameterType="int" resultMap="studentResult">
	select * from student1 where sn=#{sn}
</select>

<resultMap id="studentResult" type="entity.Student">
	<id property="sn" column="sn"/>
	<result property="sname" column="sname"/>
	<result property="ssex" column="ssex" javaType="java.lang.Boolean" jdbcType="INTEGER" />
</resultMap>

</mapper>

8.定义接口

package dao;

import entity.Student;

public interface StudentDao {
    
    
	Student converter(int sn);
}

9.编写一个测试方法和类

package test;

import java.io.IOException;
import java.io.Reader;

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 dao.StudentDao;
import entity.Student;

public class Test1 {
    
    
	
	public static void testmetheod()throws IOException{
    
    
		String resource="conf.xml";
		Reader reader=Resources.getResourceAsReader(resource);
		SqlSessionFactory sessionFactory =new SqlSessionFactoryBuilder().build(reader);
		SqlSession session =sessionFactory.openSession();
		StudentDao st=session.getMapper(StudentDao.class);
		Student student=st.converter(101);
		System.out.println(student.getSn()+","+student.getsname()+", "+student.getSsex());
		session.close();
	}
	
	public static void main(String [] agrs) throws IOException {
    
    
		testmetheod();
	}
}

10 运行测试类，查看结果

类型转换器转换成功