转！！！Mybatis实现数据的增删改查（CRUD）

2023-08-28 16:51:16

什么是 MyBatis？

MyBatis 是支持普通 SQL 查询，存储过程和高级映射的优秀持久层框架。 MyBatis 消除了几乎所有的 JDBC 代码和参数的手工设置以及对结果集的检索。MyBatis 可以使用简单的XML 或注解用于配置和原始映射，将接口和 Java 的 POJO（Plain Old Java Objects，普通的Java对象）映射成数据库中的记录。

MyBatis下载：https://github.com/mybatis/mybatis-3/releases

Mybatis实例

对一个User表的CRUD操作：

User表：

-- ----------------------------

-- Table structure for `user`

-- ----------------------------

DROP TABLE IF EXISTS `user`;

CREATE TABLE `user` (

  `id` int(11) NOT NULL AUTO_INCREMENT,

  `userName` varchar(50) DEFAULT NULL,

  `userAge` int(11) DEFAULT NULL,

  `userAddress` varchar(200) DEFAULT NULL,

  PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of user

-- ----------------------------

INSERT INTO `user` VALUES ('1', 'summer', '30', 'shanghai');

INSERT INTO `user` VALUES ('2', 'test2', '22', 'suzhou');

INSERT INTO `user` VALUES ('3', 'test1', '29', 'some place');

INSERT INTO `user` VALUES ('4', 'lu', '28', 'some place');

INSERT INTO `user` VALUES ('5', 'xiaoxun', '27', 'nanjing');

在Src目录下建一个mybatis的xml配置文件Configuration.xml

<?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>

    <!-- mybatis别名定义 -->

    <typeAliases>

        <typeAlias alias="User" type="com.mybatis.test.User"/>

    </typeAliases> 

    <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://127.0.0.1:3306/mybatis" />

            <property name="username" value="root"/>

            <property name="password" value="admin"/>

            </dataSource>

        </environment>

    </environments>

    <!-- mybatis的mapper文件，每个xml配置文件对应一个接口 -->

    <mappers>

        <mapper resource="com/mybatis/test/User.xml"/>

    </mappers>

</configuration>

定义User mappers的User.xml配置文件

<?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.mybatis.test.IUserOperation">

    <!-- select语句 -->

    <select id="selectUserByID" parameterType="int" resultType="User">

        select * from `user` where user.id = #{id}

    </select>

    <!-- 定义的resultMap，可以解决类的属性名和数据库列名不一致的问题-->

    <!-- <resultMap type="User" id="userResultMap">

        <id property="id" column="user_id"  />

        <result property="userName" column="user_userName"  />

        <result property="userAge" column="user_userAge"  />

        <result property="userAddress" column="user_userAddress"  />

    </resultMap> -->

    <!-- 返回list的select语句，注意 resultMap的值是指向前面定义好的 -->

    <!-- <select id="selectUsersByName" parameterType="string" resultMap="userResultMap">

        select * from user where user.userName = #{userName}

    </select> -->

    <select id="selectUsersByName" parameterType="string" resultType="User">

        select * from user where user.userName = #{userName}

    </select>

    <!--执行增加操作的SQL语句。id和parameterType分别与IUserOperation接口中的addUser方法的名字和参数类型一致。

    useGeneratedKeys设置为"true"表明要MyBatis获取由数据库自动生成的主键；keyProperty="id"指定把获取到的主键值注入到User的id属性-->

    <insert id="addUser" parameterType="User"

        useGeneratedKeys="true" keyProperty="id">

        insert into user(userName,userAge,userAddress)

             values(#{userName},#{userAge},#{userAddress})

    </insert>

    <update id="updateUser" parameterType="User" >

        update user set userName=#{userName},userAge=#{userAge},userAddress=#{userAddress} where id=#{id}

    </update>

    <delete id="deleteUser" parameterType="int">

        delete from user where id=#{id}

    </delete>

</mapper>

配置文件实现了接口和SQL语句的映射关系。selectUsersByName采用了2种方式实现，注释掉的也是一种实现，采用resultMap可以把属性和数据库列名映射关系定义好，property为类的属性，column是表的列名，也可以是表列名的别名！

User类的定义：

package com.mybatis.test;

public class User {

    private int id;

    private String userName;

    private int userAge;

    private String userAddress;

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public String getUserName() {

        return userName;

    }

    public void setUserName(String userName) {

        this.userName = userName;

    }

    public int getUserAge() {

        return userAge;

    }

    public void setUserAge(int userAge) {

        this.userAge = userAge;

    }

    public String getUserAddress() {

        return userAddress;

    }

    public void setUserAddress(String userAddress) {

        this.userAddress = userAddress;

    }

    @Override

    public String toString(){

        return this.userName+" "+this.userAge+" "+this.userAddress;

    }

}

IUserOperaton定义：

package com.mybatis.test;

import java.util.List;

public interface IUserOperation {

    public User selectUserByID(int id);

    public List<User> selectUsersByName(String userName);

    public void addUser(User user);

    public void updateUser(User user);

    public void deleteUser(int id);

}

IUserOperation为操作接口，函数名和mybatis的xml配置文件中的操作id名对应。

测试类Test：

package com.mybatis.test;

import java.io.Reader;

import java.util.List;

import org.apache.ibatis.io.Resources;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Test {

    private static SqlSessionFactory sqlSessionFactory;

    private static Reader reader;

    static {

        try {

            reader = Resources.getResourceAsReader("Configuration.xml");

            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    public static SqlSessionFactory getSession() {

        return sqlSessionFactory;

    }

    public void getUserByID(int userID) {

        SqlSession session = sqlSessionFactory.openSession();

        try {

            IUserOperation userOperation = session

                    .getMapper(IUserOperation.class);

            User user = userOperation.selectUserByID(userID);

            if (user != null) {

                System.out.println(user.getId() + ":" + user.getUserName()

                        + ":" + user.getUserAddress());

            }

        } finally {

            session.close();

        }

    }

    public void getUserList(String userName) {

        SqlSession session = sqlSessionFactory.openSession();

        try {

            IUserOperation userOperation = session

                    .getMapper(IUserOperation.class);

            List<User> users = userOperation.selectUsersByName(userName);

            for (User user : users) {

                System.out.println(user.getId() + ":" + user.getUserName()

                        + ":" + user.getUserAddress());

            }

        } finally {

            session.close();

        }

    }

    /**

     * 增加后要commit

     */

    public void addUser() {

        User user = new User();

        user.setUserAddress("place");

        user.setUserName("test_add");

        user.setUserAge(30);

        SqlSession session = sqlSessionFactory.openSession();

        try {

            IUserOperation userOperation = session

                    .getMapper(IUserOperation.class);

            userOperation.addUser(user);

            session.commit();

            System.out.println("新增用户ID：" + user.getId());

        } finally {

            session.close();

        }

    }

    /**

     * 修改后要commit

     */

    public void updateUser() {

        SqlSession session = sqlSessionFactory.openSession();

        try {

            IUserOperation userOperation = session

                    .getMapper(IUserOperation.class);

            User user = userOperation.selectUserByID(1);

            if (user != null) {

                user.setUserAddress("A new place");

                userOperation.updateUser(user);

                session.commit();

            }

        } finally {

            session.close();

        }

    }

    /**

     * 删除后要commit.

     *

     * @param id

     */

    public void deleteUser(int id) {

        SqlSession session = sqlSessionFactory.openSession();

        try {

            IUserOperation userOperation = session

                    .getMapper(IUserOperation.class);

            userOperation.deleteUser(id);

            session.commit();

        } finally {

            session.close();

        }

    }

    public static void main(String[] args) {

        try {

            Test test = new Test();

            // test.getUserByID(1);

            // test.getUserList("test1");

            // test.addUser();

            // test.updateUser();

            // test.deleteUser(6);

        } catch (Exception e) {

            System.out.println(e.getMessage());

        }

    }

}

原文相关地址：

代码下载：http://download.csdn.net/detail/luxiaoxun/8056559

Source Code：https://github.com/luxiaoxun/MybatisDemo

参考：

MyBatis-3-User-Guide-zh

http://legend2011.blog.51cto.com/3018495/d-5

http://mybatis.github.io/mybatis-3/zh/sqlmap-xml.html

作者：阿凡卢

出处：http://www.cnblogs.com/luxiaoxun/

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