MyBatis学习笔记(四) 注解

    使用MyBatis注解开发，可以省去类配置文件，简洁方便。但是比较复杂的SQL和动态SQL还是建议书写类配置文件。

注解还是不推荐使用的。只是了解了解！简单的CRUD可以使用注解。简单写写。

    把之前的例子改成使用注解的。

 

UserMapper.java

 

package com.cy.mybatis.mapper;

import java.util.List;
import java.util.Map;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Options;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.ResultMap;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.cy.mybatis.beans.UserBean;

public interface UserMapper {
    // 简单的增删改查可以使用注解
    // 注解+配置文件
    
    /**
     * 新增用戶
     * @param user
     * @return
     * @throws Exception
     */
    @Insert("insert into t_user value (null,user.username,user.password,user.account)")
    @Options(useGeneratedKeys=true,keyProperty="user.id")
    public int insertUser(@Param("user")UserBean user) throws Exception;
    
    
    /**
     * 修改用戶
     * @param user
     * @param id
     * @return
     * @throws Exception
     */
    @Update(" update t_user set username=#{u.username},password=#{u.password},account=#{u.account} where id=#{id}")
    public int updateUser (@Param("u")UserBean user,@Param("id")int id) throws Exception;
    
     /**
      * 刪除用戶
      * @param id
      * @return
      * @throws Exception
      */
    @Delete(" delete from t_user where id=#{id}  ")
    public int deleteUser(int id) throws Exception;
    
    
    /**
     * 根据id查询用户信息
     * @param id
     * @return
     * @throws Exception
     */
    
    @Select(" select * from t_user where id=#{id}")
    @Results({
        
        @Result(id=true,property="id",column="id",javaType=Integer.class),
        @Result(property="username",column="username",javaType=String.class),
        @Result(property="password",column="password",javaType=String.class),
        @Result(property="account",column="account",javaType=Double.class)
    })
    public UserBean selectUserById(int id) throws Exception;
     /**
      * 查询所有的用户信息
      * @return
      * @throws Exception
      */
    
    @Select(" select * from t_user")
    @ResultMap("userMap")
    public List<UserBean> selectAllUser() throws Exception;
    
    
    /**
     * 批量增加
     * @param user
     * @return
     * @throws Exception
     */
   public int batchInsertUser(@Param("users")List<UserBean> user) throws Exception;
   
   /**
    * 批量删除
    * @param list
    * @return
    * @throws Exception
    */
   public int batchDeleteUser(@Param("list")List<Integer> list) throws Exception;
   
   
   /**
    * 分页查询数据
    * @param parma
    * @return
    * @throws Exception
    */
   public List<UserBean> pagerUser(Map<String, Object> parmas) throws Exception;
   
   /**
    * 
    * 分页统计数据
    * @param parma
    * @return
    * @throws Exception
    */
    public int countUser(Map<String, Object> parmas) throws Exception;  
    
}

 UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org/DTD Mapper 3.0" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cy.mybatis.mapper.UserMapper">
<!-- 自定义返回结果集 -->
   <resultMap id="userMap" type="UserBean">
        <id property="id" column="id" javaType="java.lang.Integer"></id>
        <result property="username" column="username" javaType="java.lang.String"></result>
        <result property="password" column="password" javaType="java.lang.String"></result>
        <result property="account" column="account" javaType="java.lang.Double"></result>
    </resultMap>
    
    <!-- 批量操作和foreach标签 -->
    
    <insert id="batchInsertUser" parameterType="java.util.List">
       insert into t_user values 
        <foreach collection="users" item="users" separator=",">
         (null,#{users.username},#{users.password},#{users.account})
        </foreach>
    </insert>
    
    
    <delete id="batchDeleteUser">
       delete from t_user where id in (
         <foreach collection="list" item="list" separator=",">
          #{id}
         </foreach>
       )
    </delete>
    
    <!--collection 为用于遍历的元素（必选），支持数组、List、Set  -->
    <!-- item 表示集合中每一个元素进行迭代时的别名. -->
    <!--separator表示在每次进行迭代之间以什么符号作为分隔 符.  -->
    
    <!--#在生成SQL时，对于字符类型参数，会拼装引号
         $在生成SQL时，不会拼装引号，可用于order by之类的参数拼装
      -->
    <select id="pagerUser" parameterType="java.util.Map" resultMap="userMap">
      select * from t_user where 1=1
      <if test="username!=null">
       and username like '%${username}%'
      </if>
       limit ${index},${pageSize} 
    </select>
    
    <select id="countUser" parameterType="java.util.Map" resultType="int">
        select count(*) from t_user where 1=1 
        <if test="username != null">
            and username like '%${username}%'    
        </if>
    </select>    
    
</mapper>    

 简单的一个一对一的使用注解的。

package com.lovo.mybatis.mapper;

import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Options;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.ResultType;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import com.lovo.mybatis.beans.HusbandBean;
import com.lovo.mybatis.beans.WifeBean;

public interface HusbandMapper {
    
    /**
     * 保存丈夫
     * @param husband
     * @return
     */
    @Insert("insert into t_husband values (null,#{h.name})")
    @Options(useGeneratedKeys=true,keyProperty="h.id")
    public int saveHusband(@Param("h")HusbandBean husband);
    
    
    /**
     * 根据ID查询丈夫资料
     * @param id
     * @return
     */
    @Select("select * from t_husband where id=#{id}")
    @ResultType(HusbandBean.class)
    public HusbandBean findHusbandById(int id);
    
    
    
    /**
     * 根据ID查询丈夫与妻子资料
     * @param id
     * @return
     */
    @Select("select * from t_husband where id=#{id}")
    @Results({
        @Result(id=true,property="id",column="id",javaType=Integer.class),
        @Result(property="name",column="name",javaType=String.class),
        @Result(property="wife",column="id",javaType=WifeBean.class,one=@One(select="com.lovo.mybatis.mapper.WifeMapper.findWifeByHusbandId"))
    })
    public HusbandBean findHusbandAndWife(int id);
    
    
}

package com.cy.mybatis.mapper;

import org.apache.ibatis.annotations.ResultType;
import org.apache.ibatis.annotations.Select;

import com.cy.mybatis.beans.WifeBean;

public interface WifeMapper {
    
    
    @Select("select * from t_wife where fk_husband_id = #{id}")
    @ResultType(WifeBean.class)
    public WifeBean selectWifeByHusbandId(int id)throws Exception;

}

 注意：使用resultType时，一定要保证，你属性名与字段名相同；如果不相同，就使用resultMap 。