MyBatis环境搭建

本是古典何须时尚 2023-07-17 15:59 4阅读 0赞

1、新建web项目（也可以新建java项目）  
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2、导入Mybatis相关的jar包  
2.1下载jar包，然后解压。（源码也可下载）  
[https://github.com/mybatis/mybatis-3/releases/tag/mybatis-3.2.7][https_github.com_mybatis_mybatis-3_releases_tag_mybatis-3.2.7]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1N0cml2ZXIwMA_size_16_color_FFFFFF_t_70 1]  
2.2导入  
复制jar包到lib下  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1N0cml2ZXIwMA_size_16_color_FFFFFF_t_70 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1N0cml2ZXIwMA_size_16_color_FFFFFF_t_70 3]  
另外，还需要导入数据库驱动。  
3、在src下新建全局配置文件  
全局配置文件没有名称和地址要求 ，在全局配置文件中引入 DTD 或 schema

<?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="default">  <environment id="default">  <transactionManager type="JDBC"></transactionManager> <dataSource type="POOLED"> <property name="driver" value="com.mysql.cj.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/ssm?useSSL=false&serverTimezone=Hongkong&characterEncoding=utf-8" /> <property name="username" value="root" /> <property name="password" value="123456" /> </dataSource> </environment> </environments> <mappers> <mapper resource="com/test/mapper/UserMappper.xml" /> </mappers>
    </configuration>

4、  
新建以 mapper 结尾的包,在包下新建:实体类名+Mapper.xml  
文件作用:编写需要执行的 SQL 命令  
把 xml 文件理解成实现类  
id:方法名  
parameterType:定义参数类型  
resultType:返回值类型.

如果方法返回值是list,在resultType中写List的泛型,因为mybatis  
对jdbc封装,一行一行读取数据

<?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.test.mapper.UserMappper" >
    	<select id="selAll" resultType="com.test.pojo.User">
    		select * from user
    	</select>
    </mapper>

namespace也可以写成别的  
5、测试

package com.test.test;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.List;
    
    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 com.test.pojo.User;
    
    public class Test { 
    	public static void main(String[] args) throws IOException { 
    		InputStream is = Resources.getResourceAsStream("mybatis.xml");
    		// 使用工厂设计模式
    		SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
    		// 生产SqlSession
    		SqlSession session = factory.openSession();
    
    		List<User> list = session.selectList("com.test.mapper.UserMappper.selAll");
    		for (User user : list) { 
    			System.out.println(user.toString());
    		}
    
    		session.close();
    	}
    }

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以上为mysql8，mysql5的不同如下  
dataSource改为

mysql驱动改为  
![在这里插入图片描述][20200323145701467.png]

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[https_github.com_mybatis_mybatis-3_releases_tag_mybatis-3.2.7]: https://github.com/mybatis/mybatis-3/releases/tag/mybatis-3.2.7
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1N0cml2ZXIwMA_size_16_color_FFFFFF_t_70 2]: /images/20230528/78c26f2be957437c92246ed96731e8c9.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1N0cml2ZXIwMA_size_16_color_FFFFFF_t_70 4]: /images/20230528/938697bc19e646f8a6c674386d0aa017.png
[20200323145701467.png]: /images/20230528/25eee182fd914f1daf8e00e01ae785fd.png