MyBatis第一个项目

MyBatis快速入门

1. 创建user表，添加数据

   CREATE DATABASE mybatis;
   USE mybatis;
   ​
   DROP TABLE IF EXISTS tb_user;
   ​
   CREATE TABLE tb_user(
       id INT PRIMARY KEY AUTO_INCREMENT,
       username VARCHAR(20),
       PASSWORD VARCHAR(20),
       gender CHAR(1),
       addr VARCHAR(30)
   );
   ​
   INSERT INTO tb_user VALUES (1,'zhangsan','123','男','北京');
   INSERT INTO tb_user VALUES (2,'李四','234','女','天津');
   INSERT INTO tb_user VALUES (3,'王五','11','男','西安');

    

    

2. 创建模块，导入坐标

3. 编写MyBatis核心配置文件 --> 替换连接信息 解决硬编码问题

4. 编写SQL映射文件 --> 统一管理SQL语句，解决硬编码问题

5. 编码

   1. 定义pojo类

   2. 加载核心配置文件，获取SqlSessionFactory对象

   3. 获取SqlSession对象，执行SQL语句

      SqlSession sqlSession = sqlSessionFactory.openSession();
      List<User> users = sqlSession.selectList("test.selectAll");

       

       

   4. 释放资源

      sqlSession.close();

       

1. 编写pom.xml配置文件

<?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>mybatis-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
​
    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>
​
    <dependencies>
        <!-- mybatis 依赖 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>
​
        <!-- mysql 驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>
​
        <!-- junit 单元测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>
​
        <!-- 添加slf4j日志api -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.20</version>
        </dependency>
​
        <!-- 添加logback-classic依赖 -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>
​
        <!-- 添加logback-core依赖 -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.2.3</version>
        </dependency>
​
​
    </dependencies>
​
</project>

 

 

2. 创建User类在com.uestc.pojo

public class User {
​
    private Integer id;
    private String username;
    private String password;
    private String gender;
    private String addr;
​
    public Integer getId() {
        return id;
    }
​
    public void setId(Integer id) {
        this.id = id;
    }
​
    public String getUsername() {
        return username;
    }
​
    public void setUsername(String username) {
        this.username = username;
    }
​
    public String getPassword() {
        return password;
    }
​
    public void setPassword(String password) {
        this.password = password;
    }
​
    public String getGender() {
        return gender;
    }
​
    public void setGender(String gender) {
        this.gender = gender;
    }
​
    public String getAddr() {
        return addr;
    }
​
    public void setAddr(String addr) {
        this.addr = addr;
    }
​
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", gender='" + gender + '\'' +
                ", addr='" + addr + '\'' +
                '}';
    }
}

 

3. 在resources下创建并编写mybatis-config.xml配置文件

<?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">
                <!-- 数据库连接信息 -->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!-- 加载sql映射文件 -->
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

 

4. 继续创建logback.xml文件并编写

<?xml version="1.0" encoding="UTF-8" ?>
<configuration>
​
    <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>[%level] %blue(%d{HH:mm:ss.SSS}) %cyan([%thread]) %boldGreen(%logger{15}) - %msg %n
            </pattern>
        </encoder>
    </appender>
​
    <logger name="com.itheima" level="DEBUG" additivity="false">
        <appender-ref ref="Console"/>
    </logger>
​
​
</configuration>

 

5. 继续创建并编写UserMapper.xml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">
​
<!--
    namespace:名称空间
 -->
<mapper namespace="test">
    <select id="selectAll" resultType="com.uestc.pojo.User">
        select * from  tb_user;
    </select>
​
</mapper>

 

6. 最后在com.uestc下面创建一个MyBatisDemo的类

/**
 * MyBatis 快速入门代码
 */
public class MyBatisDemo {
​
    public static void main(String[] args) throws IOException {
        //1. 加载mybatis的核心配置文件，获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
​
​
        //2. 获取SqlSession对象，用它来执行sql
        SqlSession sqlSession = sqlSessionFactory.openSession();
​
        //3. 执行sql
        List<User> users = sqlSession.selectList("test.selectAll");
​
        System.out.println(users);
​
        //4. 释放资源
        sqlSession.close();
​
​
    }
}

 

7. 控制台最后输出结果

[User{id=1, username='zhangsan', password='123', gender='男', addr='北京'}, User{id=2, username='李四', password='234', gender='女', addr='天津'}, User{id=3, username='王五', password='11', gender='男', addr='西安'}]