mybatis

1.導(dǎo)價(jià)包 (mybatis-3.2.2.jar mysql-connector-java-5.1.21.jar)
2.添加文件(mybatis-config.xml,mybatis-config.xml)
3.配置文件

<mappers>
        <!-- 配置映射文件 -->
        <mapper resource="com/mapper/EmpMapper.xml"/>
    </mappers>

<mapper namespace="com.dao.IUserDao">
<select id="list" resultType="com.model.User">
            select * from employee
</select>
<insert id="save" parameterType="com.model.User" >
 insert into employee(username) values(#{username})
</insert>
     <update id="update"  parameterType="com.model.User" >
     update employee set username=#{username} where id=#{id}
     
     </update>
    <delete id="delete" parameterType="com.model.User" >
    delete from employee where id=#{id}
    </delete> 
</mapper>

執(zhí)行sql

  Reader r = Resources.getResourceAsReader("mybatis-config.xml");
              SqlSessionFactory ss=new SqlSessionFactoryBuilder().build(r);
              SqlSession session = ss.openSession();

方法一：
通過(guò)session.getMapper().IUserDao中的方法

方法二：

 session.insert("save",new User("萊恩"));
session.delete("delete",new User(34,""));
session.update("update",new User(27,"陳一發(fā)"));
           session.commit();

<delete id="delete" parameterType="com.model.User" >
    delete from employee <include refid="byId"></include>
    </delete> 

<sql id="byId">
    where id=#{id}
    </sql>

屬性與字段映射

1.自動(dòng)映射

<select id="list" resultType="com.model.User">//字段名與屬性名不同時(shí)通過(guò)取別名映射

select salary sal from employee

2.手動(dòng)映射

<resultMap type="com.model.User" id="userMap">
<result property="sal" column="salary" javaType="java.lang.Double"/>
</resultMap>
<select id="list" resultMap="userMap">

使用mybatis

1.讀取配置文件

 Reader r = Resources.getResourceAsReader("mybatis-config.xml");

2.創(chuàng)建session工廠

 SqlSessionFactory ss=new SqlSessionFactoryBuilder().build(r);

3.得到session

SqlSession session = ss.openSession();

4.通過(guò)session執(zhí)行sql語(yǔ)句

  session.getMapper(IUserDao.class).save(new User("撼地神牛"));
  通過(guò)對(duì)應(yīng)關(guān)系
    session.insert("save",new User("萊恩"));
    通過(guò)Mapper文件中設(shè)置的方法的ID

5.處理結(jié)果集

6.關(guān)閉session

##條件查詢
``` xml
<select id="list" resultType="com.model.User" parameterType="com.model.User">
        select * from employee 
        <where>
        <if test="id!=0">
        and id=#{id}
        </if>
        <if test="username!=null and username!=''">
        and username like concat('%',#{username},'%')
        </if>
        </where>
        limit #{startIndex},#{size}
    </select>