MyBatis开发dao的两种方式

原始dao的开发

需要编写dao接口及其实现类

需要在dao实现类中注入一个SqlSessionFactory

user.xml

<!DOCTYPE mapper
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 对sql进行分开处理，隔离 -->
<mapper namespace="com.hl.mybatis.first.mapper.UserMapper">
    <!-- 执行数据库的查询 ID用来标识次sql语句，称为Statement的ID  
        #{}表示一个占位符
        parameterType指定输入参数类型
        id:接收参数名叫id,如果参数为简单类型，参数名随意
        resultType:输出结果的类型,单条记录所映射的对象类。
    -->
    <select id="findUserById" parameterType="int" resultType="com.hl.myabtis.first.beas.User">
        select * FROM user WHERE id = #{id}
    </select>
    <!--${value}表示sql拼接串  -->
    <select id="findUserByName" parameterType="String" resultType="com.hl.myabtis.first.beas.User">
        select * FROM user WHERE address LIKE '%${value}%'
    </select>

    <!-- 添加用户 
        SELECT_LAST_INSERT_ID()只适用于自增长情况
        keyProperty:将查询到的结果设置到parameterType指定的属性
        order：执行顺序，在插入后执行
        resultType：结果类型
    -->
    <insert id="insertUser" parameterType="com.hl.myabtis.first.beas.User">
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
        SELECT LAST_INSERT_ID()
    </selectKey>
        insert into user (username,birthday,sex,address) value(#{username},#{birthday},#{sex},#{address})
    </insert>
    <!-- 删除 
        parameterType:参数类型
    -->
    <delete id="deleteUser" parameterType="java.lang.Integer">
        delete from user where id = #{value}
    </delete>
    <!-- 更新
        需求：根据ID更新用户信息
        parameterType:需要更新的用户信息
        #{id}：从输入的user对象中获取ID属性，名称需要和属性名一致
     -->
     <update id="updateUserByID" parameterType="com.hl.myabtis.first.beas.User">
        update user set username = #{username},birthday = #{birthday},sex = #{sex},address = #{address} where id = #{id}
     </update>
</mapper>      

接口：

package com.hl.mybatis.first.dao;


import java.util.List;

import com.hl.myabtis.first.beas.User;

public interface IUserDAO {

    //根据id查询用户信息
    public User finfUserById(int id) throws Exception;
    //添加用户信息
    public void insertUser(User user);
    //根据id删除用户
    public void deleteUser(int id);
    //根据用户姓名模糊查找
    public List<User> findUserByName(String name);
}      

接口的实现

package com.hl.mybatis.first.daoimpl;

import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import com.hl.myabtis.first.beas.User;
import com.hl.mybatis.first.dao.IUserDAO;

public class UserDaoImpl implements IUserDAO {

    private SqlSessionFactory sqlSessionFactory;
    //通过构造函数注入sqlSessionFactory
    public UserDaoImpl(SqlSessionFactory sqlSessionFactory){
        this.sqlSessionFactory = sqlSessionFactory;
    }
    @Override
    public User finfUserById(int id) throws Exception {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        User user = sqlSession.selectOne("test.findUserById", id);
        sqlSession.close();
        return user;
    }

    @Override
    public void insertUser(User user) {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        sqlSession.insert("test.insertUser", user);
        sqlSession.commit();
        sqlSession.close();
    }

    @Override
    public void deleteUser(int id) {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        sqlSession.delete("test.deleteUser", id);
        sqlSession.commit();
        sqlSession.close();
    }
    @Override
    public List<User> findUserByName(String name) {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<User> list = sqlSession.selectList("test.findUserByNaem", name);
        sqlSession.close();
        return list;
    }

}      

Mapper代理开发