mybatis_2

Posted 2020-10-27 千彧

 

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3   PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4   "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5   <!-- 全局配置文件 -->
 6 <configuration>
 7   <environments default="development">
 8     <environment id="development">
 9       <transactionManager type="JDBC"/>
10       <dataSource type="POOLED">
11         <property name="driver" value="com.mysql.jdbc.Driver"/>
12         <property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf8"/>
13         <property name="username" value="root"/>
14         <property name="password" value="root"/>
15       </dataSource>
16     </environment>
17   </environments>
18 
19   <!-- 加载映射文件 -->
20   <mappers>
21     <mapper resource="EmployeeMapper1.xml"/>
22     <mapper resource="EmployeeMapper2.xml"/>
23   </mappers>
24 </configuration>

 

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper
 3   PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4   "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 
 6 <!-- demo2 -->
 7 <mapper namespace="com.demo2.EmployeeMapper">
 8     <!-- 
 9             mybatis 支持命名空间设置为 dao 接口 进行绑定   框架会自动对接口进行代理  不需要手动实例化
10                     sql 唯一id与接口中的方法进行绑定  这里的接口只需要设定好方法的参数而不需要实例化
11      -->
12       <select id="getById" resultType="org.entity.Employee">
13         select * from employee where id = #{id}
14       </select>
15 </mapper>

 

 1 package demo2;
 2 
 3 import java.io.IOException;
 4 import java.io.InputStream;
 5 
 6 import org.apache.ibatis.io.Resources;
 7 import org.apache.ibatis.session.SqlSession;
 8 import org.apache.ibatis.session.SqlSessionFactory;
 9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
10 import entity.Employee;
11 
12 public class Demo2 {
13 
14     public static void main(String[] args) throws IOException {
15         // 1、获取sessionFactory
16         String resource = "mybatis-config.xml";
17         InputStream inputStream = Resources.getResourceAsStream(resource);
18         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
19                 .build(inputStream);
20         // 2、获取 session
21         SqlSession session = sqlSessionFactory.openSession();
22         // 3、获取接口的是实现类对象 自动代理
23         EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
24 
25         Employee employee = mapper.getById(1);
26         System.out.println(employee.toString());
27         session.close();
28     }
29 }