Mybatis基础学习(一)

1.使用Maven来创建一个简单的Mybatis项目
2.在pom.xml中添加Mybatis框架所需要依赖的坐标(jar包)

    <?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.jiahao</groupId>
    <artifactId>day01_easy_01Mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.8</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>
    </dependencies>
</project>

3.完成主要配置文件的编写(数据库连接和指定映射配置文件的位置[目的是为了不用自己实现数据库查询方法])

<?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>
    <!--配置环境 -->
    <environments default="mysql">
        <!-- 配置mysql环境-->
        <environment id="mysql">
            <!--配置事务的类型 -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 配置数据源连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/easy"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
       <mapper resource="com/jiahao/dao/IUserDao.xml"></mapper>
        <!--    <mapper class="com.jiahao.Dao.IUserDao"></mapper> -->
       </mappers>
   </configuration>

4.完成指定映射配置文件的位置，即UserDao.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.jiahao.dao.IUserDao">
    <!--配置查询所有-->
    <select id="findAll" resultType="com.jiahao.domain.User">
        select * from user
    </select>

</mapper>

main函数

package com.jiahao.test;
import com.jiahao.dao.IUserDao;
import com.jiahao.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;

/**
 * @author HuJiahao
 * @version 1.0
 * @date 2021/1/13 18:42
 */
public class MybatisTest {
    public static void main(String[] args) throws Exception{
        //1.读取配置文件
        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlsessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂生产sqlsession
        SqlSession session = factory.openSession();
        //4.使用sqlsessionc创建Dao接口的代理对象
        IUserDao userDao = session.getMapper(IUserDao.class);
        //5.使用代理对象执行方法
        List<User> users = userDao.findAll();
        for (User user : users){
            System.out.println(user);
        }
        //6解释资源
        session.close();
        in.close();
    }
}