1. Add operation

1.1 add insertUser() method in UserMapper interface

public interface UserMapper {
    /**
     * Query all users
     *
     * @return
     */
    List<User> listAllUsers();

    /**
     * Add user
     * @param user
     * @return 1 for success, 0 for failure
     */
    int insertUser(User user);
}

1.2 configure add operation in Mapper mapping file 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="cn.ykf.mapper.UserMapper">
    <!-- Configure query all users -->
    <select id="listAllUsers" resultType="cn.ykf.pojo.User">
        SELECT * FROM user
    </select>
    <!-- Add user -->
    <insert id="insertUser" parameterType="cn.ykf.pojo.User">
        INSERT INTO user(username,birthday,sex,address) VALUES (#{username},#{birthday},#{sex},#{address})
    </insert>
</mapper>

• Reminder
  • When writing a mapping file, you can first write a SQL statement that can run normally on the MySQL client, then move it to the mapping file, and replace the original actual parameters with the parameter symbols of Mybatis

1.3 test add operation

public class MybatisTest {

    private InputStream is;
    private SqlSession sqlSession;
    private UserMapper mapper;

    /**
     * Execute before test, for initialization
     */
    @Before
    public void init() throws Exception {
        // 1. Read configuration file
        is = Resources.getResourceAsStream("mybatis-config.xml");
        // 2. Create SqlSessionFactory factory
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(is);
        // 3. Get SqlSession object
        sqlSession = factory.openSession();
        // 4. Use SqlSession to create Mapper's proxy object
        mapper = sqlSession.getMapper(UserMapper.class);
    }

    /**
     * End of test execution for commit transactions and release resources
     */
    @After
    public void destory() throws Exception {
        // 6. Submission
        sqlSession.commit();
        // 7. Release resources
        sqlSession.close();
        is.close();
    }

    /**
     * Test add user
     */
    @Test
    public void testInsertUser() {
        User user = new User();
        user.setUsername("Fish meal");
        user.setBirthday(new Date());
        user.setSex("male");
        user.setAddress("Guangdong");

        // Call mapper to finish adding
        int count = mapper.insertUser(user);
        System.out.println("Add the number of : " + count);
    }
}

1.4 test results

2. Delete

2.1 add the deleteUserById() method in the UserMapper interface

/**
 * Delete user by id
 *
 * @param userId
 * @return 1 for success, 0 for failure
 */
int deleteUserById(Integer userId);

2.2 configure deletion in Mapper mapping file UserMapper.xml

<!-- delete user -->
<delete id="deleteUserById" parameterType="java.lang.Integer">
    DELETE FROM user WHERE id = #{uid}
</delete>

2.3 test deletion

/**
 * Test delete user
 */
@Test
public void testDeleteUserById(){
    // The id passed here is the id value existing in your database
    int count = mapper.deleteUserById(50);
    System.out.println("The number of deleted items is: " + count);
}

2.4 test results

3. Modify

3.1 add the updateUser method in the UserMapper interface

/**
 * Modify user
 * @param user
 * @return 1 for success, 0 for failure
 */
int updateUser(User user);

3.2 configure modification in Mapper mapping file UserMapper.xml

<!-- Modify user -->
<update id="updateUser" parameterType="cn.ykf.pojo.User">
    UPDATE user SET username = #{username}, birthday = #{birthday}, sex = #{sex}, address = #{address} WHERE id = #{id}
</update>

3.3 test modification

/**
 * Test modify user
 */
@Test
public void testUpdateUser() {
    // Because the user has not been queried according to the id, the simulation data
    User user = new User();
    user.setUsername("update");
    user.setAddress("test");
    user.setSex("female");
    user.setBirthday(new Date());
    // id is the value existing in its own database
    user.setId(49);

    // Execution modification
    int count = mapper.updateUser(user);
    System.out.println("The number of modifications is: " + count);
}

3.4 test results