MyBatis入门到精通——入门篇

灰太狼 2023-09-29 10:31 30阅读 0赞

**目录**

一、什么是 MyBatis？

二、入门案例

（1）创建maven项目

（2）引入依赖包

（3）创建数据库执行sql脚本

三、入门程序源码

（1）User.java

（2）UserMapper.java

（3）MybatisUtils.java

（4）UserMapperTest.java

（6）UserMapper.xml

（7）mybatis-config.xml

（8）pom.xml

四、程序单元测试结果

五、程序完整源码获取

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

## 一、什么是 MyBatis？ ##

> MyBatis 是一款优秀的持久层框架，它支持自定义 SQL、存储过程以及高级映射。MyBatis 免除了几乎所有的 JDBC 代码以及设置参数和获取结果集的工作。MyBatis 可以通过简单的 XML 或注解来配置和映射原始类型、接口和 Java POJO（Plain Old Java Objects，普通老式 Java 对象）为数据库中的记录。
> 
> Mybatis官网文档：[https://mybatis.org/mybatis-3/zh/getting-started.html][https_mybatis.org_mybatis-3_zh_getting-started.html]

## 二、入门案例 ##

### （1）创建maven项目 ###

在此之前，需要提前配置好java环境变量和maven环境变量。

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16][]

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16 1][]

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16 2][]

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16 3][]

### （2）引入依赖包 ###

> 在[https://mvnrepository.com/][https_mvnrepository.com] 搜索添加到pom.xml中
> 
> 注意：如果使用到lombok需要用IDEA转上lombok插件。

<dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.5.9</version>
            </dependency>
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>8.0.28</version>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.18.22</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
            </dependency>

### （3）创建数据库执行sql脚本 ###

/*
     Navicat Premium Data Transfer
    
     Source Server         : 本地数据库
     Source Server Type    : MySQL
     Source Server Version : 50733
     Source Host           : localhost:3306
     Source Schema         : mybatis-simple
    
     Target Server Type    : MySQL
     Target Server Version : 50733
     File Encoding         : 65001
    
     Date: 16/04/2022 23:11:46
    */
    
    SET NAMES utf8mb4;
    SET FOREIGN_KEY_CHECKS = 0;
    
    -- ----------------------------
    -- Table structure for t_user
    -- ----------------------------
    DROP TABLE IF EXISTS `t_user`;
    CREATE TABLE `t_user`  (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `username` varchar(255) CHARACTER SET utf8 COLLATE utf8_bin NULL DEFAULT NULL,
      `password` varchar(255) CHARACTER SET utf8 COLLATE utf8_bin NULL DEFAULT NULL,
      PRIMARY KEY (`id`) USING BTREE
    ) ENGINE = InnoDB AUTO_INCREMENT = 3 CHARACTER SET = utf8 COLLATE = utf8_bin ROW_FORMAT = Dynamic;
    
    -- ----------------------------
    -- Records of t_user
    -- ----------------------------
    INSERT INTO `t_user` VALUES (1, 'admin1', '123456');
    INSERT INTO `t_user` VALUES (2, 'admin2', '123456');
    
    SET FOREIGN_KEY_CHECKS = 1;

## 三、入门程序源码 ##

**项目目录结构**

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_17_color_FFFFFF_t_70_g_se_x_16][]

### （1）User.java ###

package com.mybatis.entity;
    
    import lombok.Data;
    
    import java.io.Serializable;
    
    @Data
    public class User implements Serializable {
    
        private Integer id;
    
        private String username;
    
        private String password;
    }

### （2）UserMapper.java ###

package com.mybatis.mapper;
    
    import com.mybatis.entity.User;
    
    import java.util.List;
    public interface UserMapper {
    
        public List<User> selectUserList();
    }

### （3）MybatisUtils.java ###

package com.mybatis.util;
    
    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;
    
    public class MybatisUtils {
        private static SqlSessionFactory sqlSessionFactory;
    
        static {
            try {
                // 获取sqlSessionFactory对象
                String resource = "mybatis-config.xml";
                InputStream inputStream = Resources.getResourceAsStream(resource);
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    
        public static SqlSession getSqlSession() {
            SqlSession sqlSession = sqlSessionFactory.openSession();
            return sqlSession;
        }
    
    }

### （4）UserMapperTest.java ###

package com.mybatis;
    
    import com.mybatis.entity.User;
    import com.mybatis.mapper.UserMapper;
    import com.mybatis.util.MybatisUtils;
    import org.apache.ibatis.session.SqlSession;
    import org.junit.Test;
    
    import java.util.List;
    
    public class UserMapperTest {
    
        @Test
        public void test() {
            // 第一步: 获得sqlSession对象
            SqlSession sqlSession = MybatisUtils.getSqlSession();
            // 执行 这个过程就相当于创建一个interface的对象
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            List<User> userList = mapper.selectUserList();
            userList.forEach(System.out::println);
            sqlSession.close();
        }
    }

### （6）UserMapper.xml ###

<?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.mapper.UserMapper">
        
        <select id="selectUserList" resultType="com.mybatis.entity.User">
            select * from t_user
        </select>
    </mapper>

### （7）mybatis-config.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>
    
        <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-simple"/>
                    <property name="username" value="root"/>
                    <property name="password" value="123456"/>
                </dataSource>
            </environment>
    
        </environments>
    
        <mappers>
            <package name="com.mybatis.mapper"/>
        </mappers>
    </configuration>

### （8）pom.xml ###

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.mybatis</groupId>
        <artifactId>mybatis-simple</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <dependencies>
            
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.5.9</version>
            </dependency>
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>8.0.28</version>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.18.22</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
            </dependency>
        </dependencies>
    
        <properties>
            <maven.compiler.source>8</maven.compiler.source>
            <maven.compiler.target>8</maven.compiler.target>
        </properties>
    
    
    </project>

## 四、程序单元测试结果 ##

运行UserMapperTest类，输出以下结果，就说明运行成功了。

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16 4][]

## 五、程序完整源码获取 ##

> [https://download.csdn.net/download/qq\_19309473/85157975][https_download.csdn.net_download_qq_19309473_85157975]

[https_mybatis.org_mybatis-3_zh_getting-started.html]: https://mybatis.org/mybatis-3/zh/getting-started.html
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16]: https://img-blog.csdnimg.cn/0f1488d539464d0aa343fe7711e83d20.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAUm9jLXhi,size_20,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16 1]: https://img-blog.csdnimg.cn/d22eea9f56684adc800368428214d802.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAUm9jLXhi,size_20,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16 2]: https://img-blog.csdnimg.cn/9bea62ab85be423db662169c3c349b9f.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAUm9jLXhi,size_20,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16 3]: https://img-blog.csdnimg.cn/35dba23387d34deb8b842b87dd7872d8.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAUm9jLXhi,size_20,color_FFFFFF,t_70,g_se,x_16
[https_mvnrepository.com]: https://mvnrepository.com/
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_17_color_FFFFFF_t_70_g_se_x_16]: https://img-blog.csdnimg.cn/860e7d3540be418e8a468a2a420a89a0.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAUm9jLXhi,size_17,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAUm9jLXhi_size_20_color_FFFFFF_t_70_g_se_x_16 4]: https://img-blog.csdnimg.cn/21c2ba39fea54b3d8201d5a49186507d.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAUm9jLXhi,size_20,color_FFFFFF,t_70,g_se,x_16
[https_download.csdn.net_download_qq_19309473_85157975]: https://download.csdn.net/download/qq_19309473/85157975