MyBatis中mapper.java和mapper.xml的关系说明
作者：Hommmmmmm
这篇文章主要介绍了MyBatis中mapper.java和mapper.xml的关系说明,具有很好的参考价值,希望对大家有所帮助,如有错误或未考虑完全的地方,望不吝赐教
mapper.java和mapper.xml的关系
1.SysUser.java
public class SysUser extends BaseEntity
{
private static final long serialVersionUID = 1L;
private Long userId;
private Long deptId;
private String userName;
private String nickName;
private String email;
......
}2.SysUserMapper.java
public interface SysUserMapper
{
public List<SysUser> selectUserList(SysUser sysUser);
public SysUser selectUserByUserName(String userName);
public SysUser selectUserById(Long userId);
public int insertUser(SysUser user);
......
}接口定义有以下特点：
- 1.Mapper 接口方法名和 SysUserMapper.xml 中定义的每个 statement 的 id 同名。
- 2.Mapper 接口方法的输入参数类型和 SysUserMapper.xml 中定义的 statement 的parameterType 类型相同。
- 3.Mapper 接口的返回类型和 SysUserMapper.xml 中定义的 statement 的 resultType 类型相同。
3.SysUserMapper.xml
1.xml文件的namespace要写成mapper接口的全限定类名。
<mapper namespace="com.ruoyi.project.system.mapper.SysUserMapper">
2.statement 的id和mapper中的方法名要对应起来
比如下面，mapper中方法名为insertUser，insert的statement 标签id也要为insertUser
<insert id="insertUser" parameterType="SysUser" useGeneratedKeys="true" keyProperty="userId">
insert into sys_user(
<if test="userId != null and userId != 0">user_id,</if>
<if test="deptId != null and deptId != 0">dept_id,</if>
<if test="userName != null and userName != ''">user_name,</if>
<if test="nickName != null and nickName != ''">nick_name,</if>
<if test="email != null and email != ''">email,</if>
create_time
)values(
<if test="userId != null and userId != ''">#{userId},</if>
<if test="deptId != null and deptId != ''">#{deptId},</if>
<if test="userName != null and userName != ''">#{userName},</if>
<if test="nickName != null and nickName != ''">#{nickName},</if>
<if test="email != null and email != ''">#{email},</if>
sysdate()
)
</insert>总结
以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。