SSM 实训笔记 -13- MyBatis 入门实例，快速实现增删改查（maven）

﹏ヽ暗。殇╰゛Y 2022-04-22 15:48 208阅读 0赞

### SSM 实训笔记 -13- MyBatis 入门实例，快速实现增删改查（maven） ###

本系列文章一直没出现 Mybatis，一步一步学习，今天整理 MyBatis 入门实例

**本篇内容：**

（1）使用 MyBatis 快速实现增删改查  
（2）使用 MySQL 数据库  
（3）小项目 github 地址：

https://github.com/xpwi/mybatistest

### 一、搭建数据库 ###

（1）我们还采用之前的数据库，只需要这样一个表：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTQ3ODYz_size_16_color_FFFFFF_t_70][]

**（2）插入一些数据：**  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTQ3ODYz_size_16_color_FFFFFF_t_70 1][]

### 二、创建 Maven 项目，及配置 ###

**（1）新建项目：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTQ3ODYz_size_16_color_FFFFFF_t_70 2][]

**（2）选择组名：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTQ3ODYz_size_16_color_FFFFFF_t_70 3][]

**（3）项目名，本地位置：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTQ3ODYz_size_16_color_FFFFFF_t_70 4][]

**（4）右下角有一个提示，点击右边的选项，自动导入：**

**（5）pom.xml 文件配置：**

<dependencies>
            
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.4.6</version>
            </dependency>
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>8.0.13</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
                <scope>test</scope>
            </dependency>
    
        </dependencies>

**（6）创建 resources/jdbcConfig.properties 文件：**

并配置自己的数据库信息

driver=com.mysql.cj.jdbc.Driver
    url=jdbc:mysql://localhost:3306/数据库名?serverTimezone=UTC
    username=root
    password=密码

**（7）创建 mybatisConfig.xml 文件：**

*  注释非常详细

<?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>
        
        <properties resource="jdbcConfig.properties"> </properties>
        
        <environments default="mysql">
            <environment id="mysql">
                
                <transactionManager type="JDBC"></transactionManager>
                
                <dataSource type="POOLED">
                    
                    
                    <property name="driver" value="${driver}"></property>
                    <property name="url" value="${url}"></property>
                    <property name="username" value="${username}"></property>
                    <property name="password" value="${password}"></property>
                </dataSource>
            </environment>
        </environments>
    
        
        <mappers>
            
            
            
            <mapper resource="UserMapper.xml"/>
        </mappers>
    </configuration>

### 三、编写测试类 ###

（1）创建 src/main/java/com/xpwi/pojo/User.java 文件：

*  ！要对应数据库中相应字段名

package com.xpwi.pojo;
    
    //本文件可使用插件自动生成，详见：https://blog.csdn.net/qq_40147863/article/details/85886166
    //实体类中的属性对应数据库中的字段, 再加上 get set 方法
    public class User {
        private int id;
        private String uname;
        private String upwd;
        private String lastLoginTime;
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public String getUname() {
            return uname;
        }
    
        public void setUname(String uname) {
            this.uname = uname;
        }
    
        public String getUpwd() {
            return upwd;
        }
    
        public void setUpwd(String upwd) {
            this.upwd = upwd;
        }
    
        public String getLastLoginTime() {
            return lastLoginTime;
        }
    
        public void setLastLoginTime(String lastLoginTime) {
            this.lastLoginTime = lastLoginTime;
        }
    
        public String getRole() {
            return role;
        }
    
        public void setRole(String role) {
            this.role = role;
        }
    
        private String role;
    
    
    }

**（2）回到 resources 目录下，创建 UserMapper.xml 文件：**

*  定义 SQL 语句
 *  可以使用插件自动生成

<?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.xpwi.mapper.UserMapper">
        
        
        <select id="findAll" resultType="com.xpwi.pojo.User">
            select * from password
        </select>
        
        <select id="findUserById" resultType="com.xpwi.pojo.User" parameterType="int">
          select * from password where id=#{id}
        </select>
        
        <insert id="insert" parameterType="com.xpwi.pojo.User">
          insert into password(uname,upwd,role) values(#{uname},#{upwd},#{role})
        </insert>
        
        <update id="update" parameterType="com.xpwi.pojo.User">
          update  password set uname=#{uname},upwd=#{upwd},role=#{role} where id=#{id}
        </update>
        
        <delete id="delete" parameterType="int">
        delete from password where id=#{id}
        </delete>
    </mapper>

**（3）编写测试类：**

import com.xpwi.pojo.User;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    import org.junit.Test;
    
    import java.io.InputStream;
    import java.util.List;
    
    public class TestMyBatis { 
    
        @Test
        public void update(){ 
            InputStream rs = TestMyBatis.class.getResourceAsStream("mybatisConfig.xml");
            SqlSessionFactory sessionFactory =new SqlSessionFactoryBuilder().build(rs);
            SqlSession sqlSession = sessionFactory.openSession();
            String str = "com.xpwi.mapper.UserMapper.update";
            User user = new User();
            user.setId(30);
            user.setUname("新修改的");
            user.setUpwd("987654321");
            user.setRole("student");
            try { 
    
                int update = sqlSession.update(str, user);
                sqlSession.commit();
                System.out.println("更新 "+update+"条记录");
            }catch (Exception e){ 
                sqlSession.rollback();
            }
    
        }
    
    // @Test
        public void insert(){ 
            InputStream rs = TestMyBatis.class.getResourceAsStream("mybatisConfig.xml");
            SqlSessionFactory sessionFactory =new SqlSessionFactoryBuilder().build(rs);
            SqlSession sqlSession = sessionFactory.openSession();
            String str = "com.xpwi.mapper.UserMapper.insert";
            User user = new User();
            user.setUname("新添加的");
            user.setUpwd("987654321");
            user.setRole("student");
            try { 
                int insert = sqlSession.insert(str, user);
                sqlSession.commit();
                System.out.println("添加 "+insert+"条记录");
            }catch (Exception e){ 
                sqlSession.rollback();
            }
        }
    
    // @Test
        public void delete(){ 
            InputStream rs = TestMyBatis.class.getResourceAsStream("mybatisConfig.xml");
            SqlSessionFactory sessionFactory =new SqlSessionFactoryBuilder().build(rs);
            SqlSession sqlSession = sessionFactory.openSession();
            String str = "com.xpwi.mapper.UserMapper.delete";
            int delete = sqlSession.delete(str,32);
            sqlSession.commit();
            System.out.println("删除 "+delete+"条记录");
        }
    
    // @Test
        public void findAll(){ 
            InputStream rs = TestMyBatis.class.getResourceAsStream("mybatisConfig.xml");
            SqlSessionFactory sessionFactory =new SqlSessionFactoryBuilder().build(rs);
            SqlSession sqlSession = sessionFactory.openSession();
            String str = "com.xpwi.mapper.UserMapper.findAll";
            List<Object> objects = sqlSession.selectList(str);
            for (Object obj:objects) { 
                User user= (User) obj;
                System.out.println(user.getUname());
                System.out.println(user.getUpwd());
                System.out.println("------------");
            }
        }
    
    // @Test
        public void findUserById() { 
            InputStream rs = TestMyBatis.class.getResourceAsStream("mybatisConfig.xml");
            SqlSessionFactory sessionFactory =new SqlSessionFactoryBuilder().build(rs);
            SqlSession sqlSession = sessionFactory.openSession();
            String str = "com.xpwi.mapper.UserMapper.findUserById";
            User o = (User)sqlSession.selectOne(str,1);
            System.out.println(o.getUname());
    
        }
    }

### 四、优化 ###

本篇还可以优化，就是实体类，及 Mapper 的 xml 文件，都可以使用 MyBatis-generator 插件自动生成，使用方法详见：[mybatis-generator 详细配置及使用，爬坑记录][mybatis-generator]，本篇入门实例，采用手写，所以说还是非常的快速好用的

### 更多文章链接 ###

*  [SSM 实训笔记][SSM]

### 支持博主 ###

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我是【No. 001】号 肖朋伟 ，感谢大家宝贵的一票 ^\_^/  
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[mybatis-generator]: https://blog.csdn.net/qq_40147863/article/details/85886166
[SSM]: https://blog.csdn.net/qq_40147863/article/category/8577666
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