Mybatis总结

来源：互联网发布：即时通讯软件怎么开发编辑：程序博客网时间：2024/06/05 03:57

整理mybatis思路：
1.代码中通过流的方式读取mybatis的配置文件，
String resource = “SqlMapConfig.xml”;
//通过流将核心配置文件读取进来
InputStream inputStream = Resources.getResourceAsStream(resource);
//通过核心配置文件输入流来创建会话工厂
private SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
2.定义映射器：编写接口mapper和配置文件mapper.xml并且要放在同一个包下面，具体的配置规则在下面的代码中体现。
3.在mybatis的配置文件中SqlMapConfig.xml中引入mapper.xml
4.具体的配置规则如下例子：
4.1接口：
/**
* 官方推荐使用这种方式
* @author Administrator
*
*/
public interface UserMapper {

public User findUserById(Integer id);//动态代理形式中,如果返回结果集问List,那么mybatis会在生成实现类的使用会自动调用selectList方法public List<User> findUserByUserName(String userName);public void insertUser(User user);public List<User> findUserbyVo(QueryVo vo);public Integer findUserCount();public List<User> findUserByUserNameAndSex(User user);public List<User> findUserByIds(QueryVo vo);

// public List findOrdersAndUser1() ;

public List<Orders> findOrdersAndUser2();public List<User> findUserAndOrders();

}

配置文件：

<?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.itheima.po.UserMapper">

   
   <sql id="user_Where">

   
       <where>
           <if test="username != null and username!=''">
               username like '%${username}%'
           </if>
           <if test="sex !=null and sex!=''">
               and sex=#{sex}
           </if>
       </where>
   </sql>
   
   <select id="findUserById" parameterType="int" resultType="com.itheima.pojo.User">
       select * from user where id=#{id};
   </select>

   
   <select id="findUserByUserName" parameterType="string" resultType="user">
       select * from user where username like '%${value}%'
   </select>

   
   <insert id="insertUser" parameterType="com.itheima.pojo.User" >
       
       <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
           select LAST_INSERT_ID()
       </selectKey>
       insert into user (username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})
   </insert>

   <select id="findUserbyVo" parameterType="com.itheima.po.QueryVo" resultType="com.itheima.po.User">
       select * from user where username like '%${user.username}%' and sex=#{user.sex};
   </select>

   
   <select id="findUserCount" resultType="java.lang.Integer">
       select count(*) from user
   </select>

   
   <select id="findUserByUserNameAndSex" parameterMap="com.itheima.pojo.User" resultType="com.itheima.pojo.User">

       select * from user ;
       <include refid="user_Where"></include>

   </select>

   <select id="findUserByIds" parameterType="com.itheima.pojo.QueryVo" resultType="com.itheima.pojo.User">
       select * from user where id in(1,16,25,26);
       <where>
           <if test="ids !=null">
                
               <foreach collection="ids" item="id" open="id in(" close=")" separator="," >
               #{id}
               </foreach>
           </if>
       </where>
   </select>

   
   
   
   <resultMap type="com.itheima.po.Orders" id="orderAndUserResultMap">
       
       <id column="id" property="id"/>
       
       <result column="user_id" property="userId"/>
       <result column="number" property="number"/>
       <result column="createtime" property="createtime"/>
       <result column="note" property="note"/>

       
       
       <association property="user" javaType="com.itheima.pojo.User">
           <id column="uid" property="id"/>
           <result column="username" property="username"/>
           <result column="birthday" property="birthday"/>
           <result column="sex" property="sex"/>
           <result column="address" property="address"/>
       </association>
   </resultMap>
   <select id="findOrdersAndUser2" resultMap="orderAndUserResultMap">
       select a.* ,b.id uid,username,birthday,sex,address from orders a, user b where a.user_id=b.id;
   </select>

   <resultMap type="com.itheima.pojo.User" id="userAndOrdersResultMap">
       <id column="id" property="id"/>
       <result column="username" property="username"/>
       <result column="birthday" property="birthday"/>
       <result column="sex" property="sex"/>
       <result column="address" property="address"/>

       
       <collection property="ordersList" ofType="com.itheima.pojo.Orders">

           <id column="oid" property="id"/>
           <result column="user_id" property="userId"/>
           <result column="number" property="number"/>
           <result column="createtime" property="createtime"/>
       </collection>
   </resultMap>

   <select id="findUserAndOrders" resultMap="userAndOrdersResultMap">
       select a.*,b.id oid ,user_id,number,createtime from user a, orders b where a.id=b.user_id;
   </select>

</mapper>

简单的配置例子：

<?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="test">
   
   <select id="findUserById" parameterType="java.lang.Integer" resultType="com.itheima.pojo.User">
       select * from user where id=#{id};
   </select>

   
   <select id="findUserByUserName" parameterType="java.lang.String" resultType="com.itheima.pojo.User">
       select * from user where username like '%${value}%'
   </select>

   
   <insert id="" parameterType="">
        
      <selectKey keyProperty="id" order="BEFORE" resultType="java.lang.Integer">
          select LAST_INSERT_ID();
      </selectKey>
      insert into user(username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address});
   </insert>

   
   <delete id="delUserById" parameterType="int">
      delete from user where id=#{id};
   </delete>

   
   <update id="updateUserById" parameterType="com.itheima.pojo.User">

      update user set username=#{username} where id=#{id};

   </update>

</mapper>

阅读全文

0 0