使用MyBatis 肯定是要生成 SqlSessionFactory
1.通过读取xml 配置文件用SqlSessionFactoryBuilder 生成
2.通过代码用 SqlSessionFactoryBuilder 生成
SqlSessionFactory的作用？
sqlSessionFactory 唯一的作用就是生产 MyBatis的核心接口对象SqlSession
一般采用单例模式处理它
SqlSession的作用？
SqlSession 的作用类似一个JDBC中的 Connection 对象代表着一个连接资源的启用。
具体
如何获得 SqlSession?
SqlSession sqlSession = SqlSessionFactoty.opensession();
SQL Mapper (映射器)的作用？
如何实现映射器？
XML 方式创建映射器
1.映射器接口
public interface RoleMapper { public int insertRole(Role role); public int deleteRole(Long id); public int updateRole(Role role); public Role getRole(Long id); public List<Role> findRoles(String roleName); }
2.RoleMapper.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="com.learn.ssm.chapter3.mapper.RoleMapper"> <insert id="insertRole" parameterType="role"> insert into t_role(role_name, note) values(#{roleName}, #{note}) </insert> <delete id="deleteRole" parameterType="long"> delete from t_role where id= #{id} </delete> <update id="updateRole" parameterType="role"> update t_role set role_name = #{roleName}, note = #{note} where id= #{id} </update> <select id="getRole" parameterType="long" resultType="role"> select id, role_name as roleName, note from t_role where id = #{id} </select> <select id="findRoles" parameterType="string" resultType="role"> select id, role_name as roleName, note from t_role where role_name like concat(‘%‘, #{roleName}, ‘%‘) </select> </mapper>
3.在 mybatis-config.xml 中引入XML配置文件
<mappers> <mapper resource="com/ssm/mapper/RoleMapper.xml"/> </mappers>
注解实现映射器
1.映射器接口
public interface RoleMapper2 { @Select("select id, role_name as roleName, note from t_role where id=#{id}") public Role getRole(Long id); }
2..在 mybatis-config.xml 中引入对应的class路径
<mappers> <mapper class="com.ssm.mapper.RoleMapper2"/> </mappers>
如何获取Mapper接口?
通过SqlSession 获取Mapper 接口，并发送SQL
RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class); Role role = roleMapper.getRole(1L);
原文：https://www.cnblogs.com/wayoufeidie/p/11809115.html