MyBatis操作数据库

select单条数据

package entity;

public class User {
private Integer id;
private String username;
private Integer age;
private Integer score;
}
package dao;

public interface UserDao {
/**
* 通过用户id查询用户信息
*
* @param id
* @return
*/
User selectUserById(Integer id);
}
<!-- mapper配置 -->
<mappers>
<mapper class="dao.UserDao"/>
</mappers>
<?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="dao.UserDao">
<select id="selectUserById" resultType="entity.User">
SELECT * FROM user WHERE id = #{id}
</select>
</mapper>
@SuppressWarnings({"Duplicates"})
public class UserTest {
public static void main(String[] args) throws IOException, SQLException {
InputStream configuration = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);
SqlSession session = sqlSessionFactory.openSession();
UserDao dao = session.getMapper(UserDao.class);
User user = dao.selectUserById(1);
System.out.println(user);
session.close();
}
}

select多条数据

<select id="selectUserList" resultType="entity.User">
SELECT * FROM user
</select>
/**
* 查询所有用户信息
*
* @return
*/
List<User> userList = dao.selectUserList();
userList.forEach(u -> System.out.println(u));

insert数据

/**
* 新增用户信息
*
* @param user
* @return
*/
<insert id="insertUser" parameterType="entity.User">
INSERT INTO user VALUES (#{id},#{username},#{age},#{score})
</insert>
List<User> userListBefore = dao.selectUserList();
userListBefore.forEach(u -> System.out.println(u));
User insertUser = new User();
insertUser.setId(6);
insertUser.setUsername("anne");
insertUser.setAge(18);
insertUser.setScore(600);
int count = dao.insertUser(insertUser);
List<User> userListAfter = dao.selectUserList();
userListAfter.forEach(u -> System.out.println(u));

update数据

/**
* 修改用户信息
*
* @param user
* @return
*/
int updateUserById(User user);
<update id="updateUserById" parameterType="entity.User">
UPDATE user SET
age = #{age},
username = #{username},
score = #{score}
WHERE id = #{id}
</update>
User模块测试类：UserTest.java
User userBefore = dao.selectUserById(6);
System.out.println(userBefore);
userBefore.setScore(900);
dao.updateUserById(userBefore);
User userAfter = dao.selectUserById(6);
System.out.println(userAfter);

delete数据

/**
* 删除用户信息
*
* @param id
* @return
*/
int deleteUserById(Integer id);
<delete id="deleteUserById">
DELETE FROM user WHERE id = #{id}
</delete>
List<User> userListBefore = dao.selectUserList();
userListBefore.forEach(u -> System.out.println(u));
int count = dao.deleteUserById(6);
List<User> userListAfter = dao.selectUserList();
userListAfter.forEach(u -> System.out.println(u));