Mybatis Web中的数据库操作方法举例详解

<?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/mybatis_demo"/>
                <property name="username" value="root"/>
                <property name="password" value="password"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50),
    email VARCHAR(50)
);

public class User {
    private int id;
    private String name;
    private String email;

    // Getters and Setters
    public int getId() { return id; }
    public void setId(int id) { this.id = id; }
    
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    
    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }
}

public interface UserMapper {
    User getUserById(int id);
    List<User> getAllUsers();
    void insertUser(User user);
    void updateUser(User user);
    void deleteUser(int id);
}

<?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="UserMapper">

    <select id="getUserById" resultType="User">
        SELECT * FROM users WHERE id = #{id}
    </select>

    <select id="getAllUsers" resultType="User">
        SELECT * FROM users
    </select>

    <insert id="insertUser" parameterType="User">
        INSERT INTO users (name, email) VALUES (#{name}, #{email})
    </insert>

    <update id="updateUser" parameterType="User">
        UPDATE users SET name = #{name}, email = #{email} WHERE id = #{id}
    </update>

    <delete id="deleteUser">
        DELETE FROM users WHERE id = #{id}
    </delete>

</mapper>

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MyBatisExample {
    public static void main(String[] args) throws IOException {
        // 1. 读取MyBatis配置文件
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        // 2. 获取SqlSession
        try (SqlSession session = sqlSessionFactory.openSession()) {
            UserMapper mapper = session.getMapper(UserMapper.class);

            // 3. 插入新用户
            User newUser = new User();
            newUser.setName("John Doe");
            newUser.setEmail("john.doe@example.com");
            mapper.insertUser(newUser);
            session.commit(); // 提交事务

            // 4. 查询所有用户
            List<User> users = mapper.getAllUsers();
            users.forEach(user -> System.out.println(user.getName() + ": " + user.getEmail()));

            // 5. 更新用户
            User existingUser = users.get(0);
            existingUser.setName("Jane Doe");
            mapper.updateUser(existingUser);
            session.commit();

            // 6. 删除用户
            mapper.deleteUser(existingUser.getId());
            session.commit();
        }
    }
}