MyBatis入门案例

sin2201

已于 2025-01-16 11:17:11 修改

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分类专栏： mybatis 文章标签： mybatis

于 2025-01-16 11:16:54 首次发布

本文链接：https://blog.youkuaiyun.com/2201_76081438/article/details/145176480

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七、主配置文件(mybatis-config.xml)

一、创建数据库和表

数据库：

表：

二、创建项目

三、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.qcby</groupId>
    <artifactId>mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <!--mybatis核心-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.7</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <!--junit测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/log4j/log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>

</project>

四、实体类

User类

package com.qcby.pojo;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable {
    private Integer id;
    private String username;
    private Date birthday;
    private String sex;
    private Integer age;
    private String address;

    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 Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", birthday=" + birthday +
                ", sex='" + sex + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                '}';
    }
}

五、UserMapper接口

package com.qcby.mapper;

import com.qcby.pojo.User;

import java.util.List;

public interface UserMapper {
    /**
     * 查询所有的用户
     */
    public List<User> findAll();
}

六、UserMapper.xml配置文件

<?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">
<mapper namespace="com.qcby.mapper.UserMapper"> <!--对谁进行操作就写谁-->

    <!--public List<User> findAll();-->
    <select id="findAll" resultType="com.qcby.pojo.User">
        select * from user;
    </select>
</mapper>

七、主配置文件(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>

    <properties resource="db.properties"></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>
        <package name="com.qcby.mapper"/>
        <!--        <mapper resource="org/mybatis/example/BlogMapper.xml"/>-->
        <!-- <mapper resource="mapper/UserMapper.xml"></mapper> -->
    </mappers>
</configuration>

八、db.properties

mysql.driver=com.mysql.jdbc.Driver
mysql.url=jdbc:mysql://localhost:3306/mybatis_demo2
mysql.username=root
mysql.password=2020

九、测试类！！

UserTest类

有两种方式

package com.qcby.test;

import com.qcby.mapper.UserMapper;
import com.qcby.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.InputStream;
import java.util.List;

public class UserTest {
    @Test
    public void findAllTest1() throws IOException {
        //加载主配置文件，目的：构建SqlSessionFactory对象
        InputStream inputStream= Resources.getResourceAsStream("mybatis-config.xml");
        //创建SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        //创建SqlSession对象(用SqlSessionFactory工厂对象)
        SqlSession sqlSession=sqlSessionFactory.openSession();
        //通过sqlSession创建UserMapper接口的代理对象
        UserMapper userMapper=sqlSession.getMapper(UserMapper.class);

        //调用查询方法
        List<User> users=userMapper.findAll();
        for(User user:users){
            System.out.println(user);
        }

        //释放资源
        sqlSession.close();
        inputStream.close();
    }
    @Test
    public void findAllTest2() throws IOException {
        //加载主配置文件，目的：构建SqlSessionFactory对象
        InputStream inputStream= Resources.getResourceAsStream("mybatis-config.xml");
        //创建SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        //创建SqlSession对象(用SqlSessionFactory工厂对象)
        SqlSession sqlSession=sqlSessionFactory.openSession();

        //调用查询方法
        List<User> users=sqlSession.selectList("com.qcby.mapper.UserMapper.findAll");
        for(User user:users){
            System.out.println(user);
        }

        //释放资源
        sqlSession.close();
        inputStream.close();
    }
}

区别：

findAllTest1

//通过sqlSession创建UserMapper接口的代理对象
UserMapper userMapper=sqlSession.getMapper(UserMapper.class);

//调用查询方法
List<User> users=userMapper.findAll();

findAllTest2

//调用查询方法
List<User> users=sqlSession.selectList("com.qcby.mapper.UserMapper.findAll");