mybatis框架对表实现增删改查 源代码

以下是一个简单的使用 MyBatis 框架进行增删改查的示例：

1. 配置文件

在 MyBatis 配置文件中，需要配置数据库连接信息、SQL 映射文件（Mapper）的位置等，例如：

<?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.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/test" />
        <property name="username" value="root" />
        <property name="password" value="123456" />
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="com/example/mappers/UserMapper.xml" />
  </mappers>
</configuration>

2. 实体类

定义一个实体类，例如：

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

3. SQL 映射文件

在 SQL 映射文件中定义 SQL 语句和对应的参数映射，例如：

<?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.mappers.UserMapper">
  <resultMap id="userMap" type="com.example.entities.User">
    <id column="id" property="id" />
    <result column="name" property="name" />
    <result column="age" property="age" />
  </resultMap>
  <select id="getUserById" resultMap="userMap">
    SELECT * FROM users WHERE id = #{id}
  </select>
  <insert id="addUser" parameterType="com.example.entities.User">
    INSERT INTO users (name, age) VALUES (#{name}, #{age})
  </insert>
  <update id="updateUser" parameterType="com.example.entities.User">
    UPDATE users SET name = #{name}, age = #{age} WHERE id = #{id}
  </update>
  <delete id="deleteUserById">
    DELETE FROM users WHERE id = #{id}
  </delete>
</mapper>

4. Dao 接口

定义一个 Dao 接口，其中的方法名要与 SQL 映射文件中的 id 名称一致，例如：

public interface UserDao {
    User getUserById(Integer id);
    void addUser(User user);
    void updateUser(User user);
    void deleteUserById(Integer id);
}

5. Dao 实现类

实现 Dao 接口，使用 MyBatis 提供的 SqlSession 和 Mapper 接口来实现增删改查，例如：

public class UserDaoImpl implements UserDao {
    private SqlSessionFactory sqlSessionFactory;
    public UserDaoImpl(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }
    @Override
    public User getUserById(Integer id) {
        try (SqlSession session = sqlSessionFactory.openSession()) {
            return session.selectOne("com.example.mappers.UserMapper.getUserById", id);
        }
    }
    @Override
    public void addUser(User user) {
        try (SqlSession session = sqlSessionFactory.openSession()) {
            session.insert("com.example.mappers.UserMapper.addUser", user);
            session.commit();
        }
    }
    @Override
    public void updateUser(User user) {
        try (SqlSession session = sqlSessionFactory.openSession()) {
            session.update("com.example.mappers.UserMapper.updateUser", user);
            session.commit();
        }
    }
    @Override
    public void deleteUserById(Integer id) {
        try (SqlSession session = sqlSessionFactory.openSession()) {
            session.delete("com.example.mappers.UserMapper.deleteUserById", id);
            session.commit();
        }
    }
}

6. 使用 Dao 接口

使用 Dao 接口中定义的方法来操作数据，例如：

public static void main(String[] args) {
    try (InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml")) {
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        UserDao userDao = new UserDaoImpl(sqlSessionFactory);
        // 查询用户
        User user = userDao.getUserById(1);
        System.out.println(user.getName() + " " + user.getAge());
        // 添加用户
        User newUser = new User();
        newUser.setName("Tom");
        newUser.setAge(20);
        userDao.addUser(newUser);
        // 更新用户
        User updateUser = new User();
        updateUser.setId(1);
        updateUser.setName("Jerry");
        updateUser.setAge(25);
        userDao.updateUser(updateUser);
        // 删除用户
        userDao.deleteUserById(2);
    } catch (IOException e) {
        e.printStackTrace();
    }
}