手把手教你写一个MyBatis入门程序-查看用户信息

本是古典何须时尚 2024-02-18 12:57 41阅读 0赞

## 手把手教你写一个MyBatis入门程序 ##

### 1.创建文件 ###

这里我就自己命名为：Code\_Book

并在构建系统时选择Maven项目

![image-20231119203808051][]

### 2.引入相关依赖 ###

pom.xml文件

![image-20231119215824234][]

<?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>org.example</groupId>
        <artifactId>Code_Book</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <properties>
            <maven.compiler.source>17</maven.compiler.source>
            <maven.compiler.target>17</maven.compiler.target>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        </properties>
        
        
        
        <dependencies>
            
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis-parent</artifactId>
                <version>37</version>
            </dependency>
            
            
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.13.2</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
    </project>

### 3.创建数据库 ###

（1）新建数据库

![image-20231119211951990][]

（2）新建一个user表（记得主键自增）

![image-20231119212356857][]

（3）输入数据

![image-20231119212526712][]

### 4.创建数据库连接信息配置文件 ###

在resources目录下直接创建db.properties文件

mysql.driver = com.mysql.cj.jdbc.Driver
    mysql.url = jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false
    mysql.username = root
    mysql.password = 123456

### 5.创建Mybatis的核心配置文件 ###

在resources目录下直接创建mybatis-config.xml文件

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration
            PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
            "https://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
        
        <properties resource="db.properties"/>
        
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="${mysql.driver}"/>
                    <property name="url" value="${mysql.url}"/>
                    <property name="username" value="${mysql.username}"/>
                    <property name="password" value="${mysql.password}"/>
                </dataSource>
            </environment>
        </environments>
    </configuration>

### 6.创建实体类（POJO实体） ###

（1）先新建一个软件包,名为：com

（2）在com中建立一个包为Study\_1

（3）创建一个pojo包；在包中，新建一个实体类，名为User。

package com.Study_1.pojo;
    
    public class User {
    
        private int uid; //用户id
        private String uname; //用户姓名
        private int uage; //用户年龄
    
    
        //写出Getter方法和Setter方法
    
        public int getUid() {
            return uid;
        }
    
        public void setUid(int uid) {
            this.uid = uid;
        }
    
        public String getUname() {
            return uname;
        }
    
        public void setUname(String uname) {
            this.uname = uname;
        }
    
        public int getUage() {
            return uage;
        }
    
        public void setUage(int uage) {
            this.uage = uage;
        }
    }

### 7.创建映射文件 ###

（1）在resources目录中创建一个mapper文件夹

（2）在mapper文件夹中创建映射文件，名为：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.Study_1.pojo.User">
    
    
        <select id="findById" parameterType="int" resultType="com.Study_1.pojo.User">
            select * from users where uid = #{id}
    
        </select>
    </mapper>

![image-20231120140630219][]

### 8.修改mybatis-config.xml文件 ###

即加mapping文件路径配置

完整的mybatis-config.xml文件如下：

### 9.编写测试类 ###

在com.Study\_1中创建Test包

然后在Test包中创建UserTest类

package com.Study_1.test;
    
    import com.Study_1.pojo.User;
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.*;
    import org.junit.Test;
    
    import java.io.IOException;
    import java.io.Reader;
    import java.sql.Connection;
    import java.sql.SQLOutput;
    
    public class UserTest {
        @Test
        public  void userFindByIdTest(){
            String resources = "mybatis-config.xml";
            Reader reader = null;
            try {
                reader = Resources.getResourceAsReader(resources);
            } catch (IOException e) {
                e.printStackTrace();
            }
            SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);
            SqlSession session = sqlMapper.openSession();
            User user = session.selectOne("findById",1);
            System.out.println(user.getUname());
            session.close();
        }
    }

### 10.运行程序 ###

![image-20231120150544220][]

[image-20231119203808051]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/18/da0eaa122f9f4280ab430601479586a4.png
[image-20231119215824234]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/18/14d446306ed141dab294bdceaa63c6f1.png
[image-20231119211951990]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/18/b5d3a0b5365f41518c7506a8f3db74d2.png
[image-20231119212356857]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/18/4ded96312f3f455da00caef92a0ba9a5.png
[image-20231119212526712]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/18/080ee36c074a4f8db6aae833e18409bb.png
[image-20231120140630219]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/18/22f66661c99d4c68b75d1c90a2a9ad50.png
[image-20231120150544220]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/18/8ef8f0eaf83c41e0b28409529dcd3350.png