MyBatis的增删改查（查询分为查询一个实体类对象、查询List集合和查询多条数据为map集合，自定义增删改查的具体内容）。用JavaEE实现

MyBatis是一种持久化框架，它可以与JavaEE中的其他框架（如Spring）一起使用。下面是一些示例代码，演示如何使用MyBatis进行增删改查。

1. 查询一个实体类对象

public class User {
    private int id;
    private String name;
    private int age;
    // 省略getter和setter
}

public interface UserMapper {
    User selectById(int id);
}

// MyBatis XML配置文件
<mapper namespace="com.example.mapper.UserMapper">
    <select id="selectById" parameterType="int" resultType="com.example.model.User">
        SELECT * FROM user WHERE id = #{id}
    </select>
</mapper>

// 使用MyBatis进行查询
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.selectById(1);

2. 查询List集合

public interface UserMapper {
    List<User> selectAll();
}

// MyBatis XML配置文件
<mapper namespace="com.example.mapper.UserMapper">
    <select id="selectAll" resultType="com.example.model.User">
        SELECT * FROM user
    </select>
</mapper>

// 使用MyBatis进行查询
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List<User> userList = userMapper.selectAll();

3. 查询多条数据为map集合

public interface UserMapper {
    List<Map<String, Object>> selectAllAsMap();
}

// MyBatis XML配置文件
<mapper namespace="com.example.mapper.UserMapper">
    <select id="selectAllAsMap" resultType="java.util.Map">
        SELECT id, name, age FROM user
    </select>
</mapper>

// 使用MyBatis进行查询
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List<Map<String, Object>> userList = userMapper.selectAllAsMap();

4. 自定义增删改查的具体内容

public interface UserMapper {
    int insert(User user);
    int update(User user);
    int delete(int id);
}

// MyBatis XML配置文件
<mapper namespace="com.example.mapper.UserMapper">
    <insert id="insert" parameterType="com.example.model.User">
        INSERT INTO user (name, age) VALUES (#{name}, #{age})
    </insert>
    
    <update id="update" parameterType="com.example.model.User">
        UPDATE user SET name = #{name}, age = #{age} WHERE id = #{id}
    </update>
    
    <delete id="delete" parameterType="int">
        DELETE FROM user WHERE id = #{id}
    </delete>
</mapper>

// 使用MyBatis进行增删改查
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

// 插入新用户
User newUser = new User();
newUser.setName("Tom");
newUser.setAge(20);
userMapper.insert(newUser);

// 更新用户信息
User updateUser = userMapper.selectById(1);
updateUser.setAge(25);
userMapper.update(updateUser);

// 删除用户
userMapper.delete(1);