【JavaEE案例】MYBatis入门程序

梦里梦外; 2024-03-25 09:38 147阅读 0赞

**1.创建工程：**启动IntelliJ IDEA，选择工具栏中的“File”→“New”→“Project”选项

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**2.数据准备：**在MySQL中创建一个名称为mybatis的数据库。

CREATE DATABASE mybatis;

在数据库中创建users表

CREATE TABLE users(
    	uid int primary key auto_increment,
    	uname varchar(20) not null,
    	uage int not null
    );

并插入几条测试数据

INSERT INTO users(uid,uname,uage) VALUES(null,'张三',20),(null,'李四',18);

**3.引入相关依赖：**在项目的pom.xml文件中导入MySQL驱动包、JUnit测试包、MyBatis的核心包等相关依赖。

<?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.mybatis</groupId>
        <artifactId>MyBatisTest</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</artifactId>
                <version>3.5.11</version>
            </dependency>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>8.0.28</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
        <build>
            <resources>
                <resource>
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.properties</include>
                        <include>**/*.xml</include>
                    </includes>
                    <filtering>true</filtering>
                </resource>
            </resources>
        </build>
    
    </project>

**4.创建POJO实体：**在com.itheima.pojo包下创建User类，该类用于封装User对象的属性。

package com.itheima.pojo;
    
    public class User {
        private int uid;
        private String uname;
        private int uage;
    
        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;
        }
    }

**5.创建映射文件UserMapper.xml：**该文件主要用于配置SQL语句和Java对象之间的映射 。

<?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.itheima.pojo.User">
        
        <select id="findById" parameterType="int"
                resultType="com.itheima.pojo.User">
            select * from users where uid = #{id}
        </select>
    </mapper>

**6.创建数据库连接信息配置文件db.properties：**在该文件中配置数据库连接的参数。

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=root

**7.创建MyBatis的核心配置文件mybatis-config.xml：**该文件主要用于项目的环境配置。

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

**8.编写测试类**

package Test;
    import com.itheima.pojo.User;
    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 org.junit.Test;
    import java.io.IOException;
    import java.io.Reader;
    
    public class UserTest {
        @Test
        public void userFindByTest() {
            String resources = "mybatis-config.xml";
            //创建流
            Reader reader = null;
            try {
                //读取mybatis-config.xml文件内容到reader对象中
                reader = Resources.getResourceAsReader(resources);
            }catch (IOException e) {
                e.printStackTrace();
            }
            //初始化MyBatis数据库，创建SqlSessionFactory类的实例
            SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);
            //创建SqlSession实例
            SqlSession session = sqlMapper.openSession();
            //传入参数查询，返回结果
            User user = session.selectOne("findById",1);
            //输出结果
            System.out.println("\n"+user.getUname());
            //关闭session
            session.close();
        }
    }

**9.运行结果**

![c19100a938144593aabcc373c8cb39a6.png][]

[c584832c783b43358148b368934cd7ac.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/25/5b83082e272e4f52ae682e661fb8d052.png
[b85b85da2bfb40cc8047c2996ca48710.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/25/9b6cbc289e38456298fe3c9781fa06fe.png
[c19100a938144593aabcc373c8cb39a6.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/25/ce45a2879c5541e7ad79bafbbbbb895d.png