MyBatis知识系列之四：解决属性名和字段名不一致的问题

1、数据库中表的设计



2、实体类：

public class User { private int id; private String name; private String password; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @Override public String toString() { return "User [id=" + id + ", name=" + name + ", password=" + password + "]"; } }

3、mapper映射文件

<select id="selectUser" resultType="User"> select * from user where id = #{id} </select>

4、问题：密码没有获取到

原因：mybatis会根据查询的列名（会将列名转为小写）去进行设值(列名setter方法)

5、解决列名和属性名不一致的办法

a)为列名指定别名别名和java实体类的属性名一致

<select id="selectUser" resultType="User"> select id,Name,pwd password from user where id = #{id} </select>

b)设置结果映射类型

<select id="selectUser" resultMap="UserMap"> select id,name,pwd from user where id = #{id} </select> <resultMap type="User" id="UserMap"> <!-- id为主键 --> <id column="id" property="id"/> <!-- column是数据库中表的列名 property是对应实体类的属性名 --> <result column="name" property="name"/> <result column="pwd" property="password"/> </resultMap>