Java使用XML与注解方式实现CRUD操作代码

<dependencies>
    <!-- MyBatis -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.6</version>
    </dependency>
    <!-- MySQL驱动 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.22</version>
    </dependency>
</dependencies>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/test_db?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/example/demo/mapper/UserMapper.xml"/>
    </mappers>
</configuration>

public class User {
    private Integer id;
    private String name;
    private Integer age;
    // getter和setter方法
}

public interface UserMapper {
    int insert(User user);
    int update(User user);
    int delete(Integer id);
    User selectById(Integer id);
    List<User> selectAll();
}

<?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.example.demo.mapper.UserMapper">
    <insert id="insert" parameterType="com.example.demo.entity.User">
        INSERT INTO user (name, age) VALUES (#{name}, #{age})
    </insert>
    <update id="update" parameterType="com.example.demo.entity.User">
        UPDATE user SET name = #{name}, age = #{age} WHERE id = #{id}
    </update>
    <delete id="delete" parameterType="java.lang.Integer">
        DELETE FROM user WHERE id = #{id}
    </delete>
    <select id="selectById" parameterType="java.lang.Integer" resultType="com.example.demo.entity.User">
        SELECT * FROM user WHERE id = #{id}
    </select>
    <select id="selectAll" resultType="com.example.demo.entity.User">
        SELECT * FROM user
    </select>
</mapper>

    @Insert("INSERT INTO user (name, age) VALUES (#{name}, #{age})")
    int insert(User user);
    @Update("UPDATE user SET name = #{name}, age = #{age} WHERE id = #{id}")
    int update(User user);
    @Delete("DELETE FROM user WHERE id = #{id}")
    int delete(Integer id);
    @Select("SELECT * FROM user WHERE id = #{id}")
    User selectById(Integer id);
    @Select("SELECT * FROM user")
    List<User> selectAll();
}

<mappers>
    <mapper class="com.example.demo.mapper.UserMapper"/>
</mappers>

String resource = "org/mybatis/example/mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

SqlSession session = sqlSessionFactory.openSession();

UserMapper mapper = session.getMapper(UserMapper.class);

// 创建新用户
User newUser = new User("John Doe", 30);
mapper.insert(newUser);
// 更新用户
newUser.setAge(31);
mapper.update(newUser);
// 删除用户
mapper.delete(newUser.getId());
// 查询单个用户
User user = mapper.selectById(newUser.getId());
// 查询所有用户
List<User> users = mapper.selectAll();

session.commit();
session.close();