mybatis(3)利用Mapper接口实现数据的增删改查

利用Mapper接口实现数据的增删改查

 重要的一点就是划线部分的命名需要有对应关系,其他的都没有变化,比如

User.java

package com.pojo;

public class User {
    private Integer id;
    private String lastName;
    private Integer sex;

    public User(Integer id, String lastName, Integer sex) {
        super();
        this.id = id;
        this.lastName = lastName;
        this.sex = sex;
    }

    public User() {
        super();
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public Integer getSex() {
        return sex;
    }

    public void setSex(Integer sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", lastName=" + lastName + ", sex=" + sex + "]";
    }

}

UserMapper.java

package com.Mapper;

import java.util.List;

import com.pojo.User;
//不需要写UserMapper的实现类
public interface UserMapper {

    public int saveUser(User user);

    public int deleteById(Integer id);

    public int updateUser(User user);

    public User queryUserById(Integer id);

    public List<User> queryUsers();
}

UserMapper.xml

<?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.Mapper.UserMapper">
    <!-- public int saveUser(User user); -->

    <insert id="saveUser" parameterType="com.pojo.User">
        insert into
        t_user(`last_name`,`sex`) values(#{lastName},#{sex})
    </insert>

    <!-- public int deleteById(Integer id); -->
    <delete id="deleteById">
        delete from t_user where id = #{id}
    </delete>

    <!-- public int updateUser(User user); -->
    <update id="updateUser" parameterType="com.pojo.User">
        update t_user set
        last_name=#{lastName},sex=#{sex} where id = #{id}
    </update>

    <!-- public User queryUserById(Integer id); -->
    <select id="queryUserById" resultType="com.pojo.User">
        select id,last_name lastName,sex from t_user where id=#{id}
    </select>



    <!-- public List queryUsers(); -->
    <select id="queryUsers" resultType='com.pojo.User'>

        select id,last_name lastName,sex from t_user

    </select>
</mapper>