支持普通 SQL 查询，存储过程和高级映射的ORM持久层框架。以一 个 SqlSessionFactory 对象的实例为核心。
从 XML 中构建 SqlSessionFactory
configuration 配置
properties 属性
settings 设置
typeAliases 类型命名
typeHandlers 类型处理器
objectFactory 对象工厂
plugins 插件
environments 环境
environment 环境变量
transactionManager 事务管理器
dataSource 数据源
映射器
String resource = "org/mybatis/example/Configuration.xml";
Reader reader = Resources.getResourceAsReader(resource);
sqlMapper = new SqlSessionFactoryBuilder().build(reader);
mybatis.cfg.xml
<?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>
<!-- 引入外部properties文件 -->
<properties resource="datasources.properties"/>
<!-- 给我们的JAVABEAN定义别名 -->
<typeAliases>
<!-- 一个一个的告知，很麻烦
<typeAlias type="com.lovo.my.beans.UserBean" alias="UserBean"/>
-->
<!-- 自动扫描包，将包内的所有JAVA类的类名，来作为该类的类别名 -->
<package name="com.lovo.my.beans"></package>
</typeAliases>
<!-- 定义mybatis运行环境,default用于设置默认环境 -->
<environments default="development">
<environment id="development">
<!-- transactionManager主要用于设置事务管理器，mybatis提供了2种事物管理器，
分别是:JDBC,MANAGED ,JDBC代表是直接使用JDBC的提交或回滚来处理事物
MANAGED 代表使用外部容器，如Spring等容器来操作事物 -->
<transactionManager type="JDBC"></transactionManager>
<!-- mybatis提供了3种数据源类型，分别是：POOLED,UNPOOLED,JNDI
POOLED 支持JDBC数据源连接池
UNPOOLD 不支持数据源连接池
JNDI 支持外部容器连接池 -->
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"></property>
<property name="url" value="${jdbc.url}"></property>
<property name="username" value="${jdbc.name}"></property>
<property name="password" value="${jdbc.password}"></property>
</dataSource>
</environment>
</environments>
<mappers>
<!--
<mapper resource="com/lovo/my/dao/IUserMapper.xml"/>
把每一个类对应的xml文件注入到mybatis中
-->
<!-- 自动扫描包，告知包内的接口与SQL映射文件 -->
<package name="com.lovo.my.dao"/>
</mappers>
</configuration>
SQL 映射的 XML 文件
cache - 配置给定命名空间的缓存。
cache-ref – 从其他命名空间引用缓存配置。
resultMap – 最复杂，也是最有力量的元素，用来描述如何从数据库结果集中来加载你的对象。
sql – 可以重用的 SQL 块，也可以被其他语句引用。
insert – 映射插入语句
update – 映射更新语句
delete – 映射删除语句
select – 映射查询语句
各种语句中的参数含义：
parameterType 方法中传入参数的类型 如入java类，list ，map 等
parameterMap
resultMap 返回结果集 一般都是 resultMap的id； 如下面最近例子 就是userMap
resultType 就表示将查询结果封装成某一个类的对象返回
<sql id="item"> 定义一个可能重复用到的sql字段等
<include refid="item"/> 引入 定义的sql语句
<?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.lovo.my.dao.IUserMapper">
<!-- 自定义映射关系 -->
<resultMap id="userMap" type="UserBean">
<result property="id" column="id" javaType="java.lang.Integer"/>
<result property="userName" column="user_name" javaType="java.lang.String"/>
<result property="password" column="password" javaType="java.lang.String"/>
<result property="salary" column="salary" javaType="java.lang.Double"/>
</resultMap>
<!-- insert 编写一个新增方法 -->
<insert id="saveUserBean" parameterType="UserBean" useGeneratedKeys="true" keyProperty="u.id">
insert into t_user (user_name,password,sex,salary) values (#{u.userName},#{u.password},#{u.sex},#{u.salary})
</insert>
<insert id="batchAddUserBean" parameterType="java.util.List">
insert into t_user (user_name,password,sex,salary) values
<foreach collection="list" item="user" separator=",">
(#{user.userName},#{user.password},#{user.sex},#{user.salary})
</foreach>
</insert>
<!-- update 编写一个修改方法，在方法中，除了Id属性是必填以外，其他属性均可不填 -->
<update id="updateUserBean">
update t_user set user_name = #{u.userName},password=#{u.password},sex=#{u.sex},salary=#{u.salary} where id= #{id}
</update>
<delete id="deleteUserBean">
delete from t_user where id = #{id}
</delete>
<!-- 批量删除的语法是： delete from t_user id in (,,,,) -->
<delete id="batchDeleteUserBean">
delete from t_user where id in
<foreach collection="list" item="id" separator="," open="(" close=")">
#{id}
</foreach>
</delete>
<select id="getUserBeanByNameAndPassword" resultMap="userMap">
select * from t_user where user_name = #{userName} and password = #{password}
</select>
<select id="findAllUserBean" resultMap="userMap">
select * from t_user
</select>
<select id="selectCountUserBeanByCondition" resultType="int">
select count(*) from t_user where 1=1
<!-- <if test="userName != null and userName != ''">
and user_name like '%${userName}%'
</if>
<if test ="sex != null and sex != ''">
and sex = #{sex}
</if> -->
<include refid="item"/>
</select>
<select id="selectUserBeanByCondition" resultMap="userMap">
select * from t_user where 1=1
<!-- <if test="userName != null and userName != ''">
and user_name like '%${userName}%'
</if>
<if test ="sex != null and sex != ''">
and sex = #{sex}
</if> -->
<include refid="item"/>
limit ${index},${rows}
</select>
<sql id="item">
<if test="userName != null and userName != ''">
and user_name like '%${userName}%'
</if>
<if test ="sex != null and sex != ''">
and sex = #{sex}
</if>
</sql>
</mapper>
one2one
关联查询 方式一
<resultMap id="wifeAndHusbandMap" type="WifeBean">
<result property="id" column="id" javaType="java.lang.Integer"/>
<result property="wifeName" column="wife" javaType="java.lang.String"/>
<association property="husband" javaType="HusbandBean">
<result property="id" column="hid" javaType="java.lang.Integer"/>
<result property="husbandName" column="hhusband" javaType="java.lang.String"/>
</association>
</resultMap>
<select id="queryWifeAndHusband" resultMap="wifeAndHusbandMap">
select w.id as wid,w.wife as wwife,h.id as hid,h.husband as hhusband from t_wife as w,t_husband as h where h.id = w.fk_husband_id and w.id = #{id}
</select>
关联查询 方式二
<resultMap id="wifeAndHusbandMap" type="WifeBean">
<result property="id" column="id" javaType="java.lang.Integer"/>
<result property="wifeName" column="wife" javaType="java.lang.String"/>
<!-- 所有的关联查询中，column="" 这一部分，一定是后面方法所需要的 -->
<association property="husband" column="fk_husband_id" select="com.lovo.my.dao.IHusbandMapper.getHusbandBeanById" javaType="HusbandBean"/>
</resultMap>
<select id="queryWifeAndHusband" resultMap="wifeAndHusbandMap">
select * from t_wife where id = #{id}
</select>
one2many
<?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.even.mapper.one2many.ILockMapper">
<resultMap type="LockBean" id="LockIncludeKeysMap">
<result property="id" column="id"/>
<result property="lockName" column="lock_name"/>
<collection property="keys" column="id" select="com.even.mapper.one2many.IKeyMapper.findByLockId"></collection>
</resultMap>
<insert id="save">
insert into t_lock(lock_name) values(#{lock.lockName})
</insert>
<select id="findById" resultType="LockBean">
select id,lock_name as lockName from t_lock where id = #{id}
</select>
<select id="findByIdIncludeKeys" resultMap="LockIncludeKeysMap">
select id,lock_name from t_lock where id = #{id}
</select>
</mapper>
<?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.even.mapper.one2many.IKeyMapper">
<resultMap type="KeyBean" id="KeyIncludeLockMap">
<result property="id" column="id"/>
<result property="keyName" column="key_name"/>
<association property="lock" column="fk_lock_id" select="com.even.mapper.one2many.ILockMapper.findById"></association>
</resultMap>
<insert id="batchSave">
insert into t_key(key_name,fk_lock_id) values
<foreach collection="list" item="key" separator=",">
(#{key.keyName},#{key.lock.id})
</foreach>
</insert>
<select id="findByIdIncludeLock" resultMap="KeyIncludeLockMap">
select id,key_name,fk_lock_id from t_key where id = #{id}
</select>
</mapper>
many2many
<?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.even.mapper.many2many.IStudentMapper">
<resultMap type="StudentBean" id="StudentMap">
<result property="id" column="id"/>
<result property="studentName" column="student_name"/>
<result property="sex" column="sex"/>
<result property="age" column="age"/>
<collection property="courses" column="id" select="findCourseByStudentId"></collection>
</resultMap>
<select id="findByIdIncludeCourses" resultMap="StudentMap">
select id,student_name,sex,age from t_student where id = #{id}
</select>
<select id="findCourseByStudentId" resultType="CourseBean">
select id,course_name as courseName from t_course where id in(select fk_course_id from t_student_course where fk_student_id = #{id})
</select>
</mapper>
<?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.even.mapper.many2many.ICourseMapper">
<resultMap type="CourseBean" id="CourseMap">
<result property="id" column="id"/>
<result property="courseName" column="course_name"/>
<collection property="students" column="id" select="findStudentByCourseId"></collection>
</resultMap>
<select id="findByIdIncludeStudents" resultMap="CourseMap">
select id,course_name from t_course where id = #{id}
</select>
<select id="findStudentByCourseId" resultType="StudentBean">
select id,student_name as studentName,sex,age from t_student where id in(select fk_student_id from t_student_course where fk_course_id = #{id})
</select>
</mapper>
<?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.even.mapper.many2many.IStudentCourseMapper">
<insert id="choiceCourse">
insert into t_student_course(fk_student_id,fk_course_id) values
<foreach collection="list" item="sc" separator=",">
(#{sc.studentBean.id},#{sc.courseBean.id})
</foreach>
</insert>
</mapper>
在没封装的情况下测试类需要这么写
package me.gacl.test;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import me.gacl.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class Test1 {
public static void main(String[] args) throws IOException {
//mybatis的配置文件
String resource = "conf.xml";
//使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）
InputStream is = Test1.class.getClassLoader().getResourceAsStream(resource);
//构建sqlSession的工厂
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
//使用MyBatis提供的Resources类加载mybatis的配置文件（它也加载关联的映射文件）
//Reader reader = Resources.getResourceAsReader(resource);
//构建sqlSession的工厂
//SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
//创建能执行映射文件中sql的sqlSession
SqlSession session = sessionFactory.openSession();
/**
* 映射sql的标识字符串，
* me.gacl.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
* getUser是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL
*/
String statement = "me.gacl.mapping.userMapper.getUser";//映射sql的标识字符串
//执行查询返回一个唯一user对象的sql
User user = session.selectOne(statement, 1);
System.out.println(user);
}
}