本文将介绍在MyBatis中,与dao对应的sql映射文件的书写,用动态sql实现对满足条件的用户集合的查询。
首先,建立一个实体类User;
package com.xyfer.pojo; public class User{ private String name; private int age; private String sex; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } }
编写DAO层接口;
packge com.xyfer.dao; public interface UserDao{ //模糊查询符合条件的用户集合 public List<User> queryUser(User user); }
在mybatis配置文件中为该类配置别名;
<typeAliases> <typeAlias type="com.xyfer.User" alias="user"/> </typeAliases>
书写UserDao接口的sql映射文件;
<mapper namespace="com.xyfer.dao.UserDao"> <resultMap type="user" id="userMapper"> <result column="name" property="name"> <result column="age" property="age"> <result column="sex" property="sex"> </resultMap> <select id="queryUser" resultMap="userMapper"> select * from user where age >=22 and age <=66 <!--动态sql拼装--> <!--如果sex有值,则加上该条件--> <if test="sex != '' and sex != null"> and sex =#{sex} </if> <!--如果name有值,则模糊匹配name--> <if test="name!= '' and name!= null"> and name like CONCAT('%',$(name),'%') </if> </select> </mapper>