intellij IDEA Mybatis入门案例

<?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.cnetopro</groupId>
    <artifactId>mybatis_mysql</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>

    <dependencies>
<!--        使用mybatis  导入前两个就行了-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.17</version>
        </dependency>

<!--单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

</project>

package com.cnetopro.domain;

import java.io.Serializable;

public class User implements Serializable {
    
    private Integer id;
    private String name;
    private Integer age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

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


    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name=‘" + name + ‘\‘‘ +
                ", age=" + age +
                ‘}‘;
    }


}

package com.cnetopro.dao;

import com.cnetopro.domain.User;

import java.util.List;
/**
 *
 * 用户持久层接口
 *
 * */
public interface IUserDao {
    /**
     * 查询所有
     * */
    List<User>findAll();
}

<?xml version="1.0" encoding="UTF-8" ?>

<!-- mapper 约束-->
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace 写的是 dao权限类名-->
<mapper namespace="com.cnetopro.dao.IUserDao">
    <!--配置查询所有-->
    <select id="findAll" resultType="com.cnetopro.domain.User">
        select * from user
    </select>

</mapper>

<?xml version="1.0" encoding="UTF-8" ?>

<!-- configuration 约束-->
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<!--mybatis的主配置文件-->
<configuration>
<!--  配置环境  -->
    <environments default="mysql">
    <!--配置mysql环境-->
        <environment id="mysql">
        <!--   配置事务类型  -->
            <transactionManager type="JDBC"></transactionManager>
            <!--  配置数据源（连接池）  -->
            <dataSource type="POOLED">
                <!--   配置连接数据库的基本信息  -->
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/test"/>
                <property name="username" value="root"/>
                <property name="password" value="zgx1734475W"/>
            </dataSource>
        </environment>
    </environments>

    <!--指定映射配置文件的位置，映射配置文件指的是每个dao配置的文件-->
    <mappers>
<!--        使用的是xml-->
        <mapper resource="com/cnetopro/dao/IUserMapper.xml"/>
<!--        <mapper class="com.cnetopro.dao.IUserMapper"/>    &lt;!&ndash;使用的是注解 annotations&ndash;&gt;-->
    </mappers>

</configuration>

package com.cnetopro.test;


import com.cnetopro.dao.IUserDao;
import com.cnetopro.domain.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 java.io.InputStream;
import java.util.List;

/**
 *
 */
public class MybatisTest {

    public static void main(String[] args) throws Exception {
//1.读取配置文件
        InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
//2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(inputStream);
//3.使用工厂创建SqlSession
        SqlSession session =factory.openSession();
//4.使用SqlSession创建dao接口的代理对象
        IUserDao userDao =session.getMapper(IUserDao.class);
//5.使用代理对象的方法
        List<User> users = userDao.findAll();
        for (User user:users
        ) {
            System.out.println(user);
        }
//6.释放资源
        session.close();
        inputStream.close();
    }
}