Mybatis--初学者

最新推荐文章于 2025-05-08 15:58:38 发布

原创最新推荐文章于 2025-05-08 15:58:38 发布 · 361 阅读

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一首先我们先来了解一下mybatis的好处和优点

1 易于上手

2 sql语句编写在xml文件中，或者是注释的方式，便于管理和降低程序代码的耦合度

3 提供对象映射标签，支持关系对象关系组维护

二搭建简单的mybatis框架需要的包是：mybatis-3.1.1.jar，mysql-connector-java-5.1.7-bin.jar

三：mybatis最主要的两个配置文件是；conf.xml

代码如下：

<?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="development">
     <environment id="development">
        <transactionManager type="JDBC"/>
        <dataSource type="POOLED">
        <property name="driver" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://localhost:3306/mytest"></property>
        <property name="username" value="root"></property>
        <property name="password" value="root"></property>

        </dataSource>

     </environment>

   </environments>

   <mappers>
 <mapper resource="com/lin/vo/userMapper.xml"></mapper> 
  <!--  <mapper class="com.lin.mapper.BlogMapper"/> -->
 
   </mappers>

</configuration>

还有一个是映射文件：userMapper.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.lin.po.userMapper">
<select id="getUser" parameterType="int" resultType="com.lin.vo.User">
  select * from users where id=#{id}


</select>
</mapper>

 实体类：

package com.lin.vo;


public class User {
<span style="white-space:pre">	</span>int id;
<span style="white-space:pre">	</span>int age;
<span style="white-space:pre">	</span>String name;
<span style="white-space:pre">	</span>public int getId() {
<span style="white-space:pre">		</span>return id;
<span style="white-space:pre">	</span>}
<span style="white-space:pre">	</span>public void setId(int id) {
<span style="white-space:pre">		</span>this.id = id;
<span style="white-space:pre">	</span>}
<span style="white-space:pre">	</span>public int getAge() {
<span style="white-space:pre">		</span>return age;
<span style="white-space:pre">	</span>}
<span style="white-space:pre">	</span>public void setAge(int age) {
<span style="white-space:pre">		</span>this.age = age;
<span style="white-space:pre">	</span>}
<span style="white-space:pre">	</span>public String getName() {
<span style="white-space:pre">		</span>return name;
<span style="white-space:pre">	</span>}
<span style="white-space:pre">	</span>public void setName(String name) {
<span style="white-space:pre">		</span>this.name = name;
<span style="white-space:pre">	</span>}
<span style="white-space:pre">	</span>public String toString(){
<span style="white-space:pre">		</span>return name;
<span style="white-space:pre">	</span>}


}

测试类：

package com.lin.test;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.lin.mapper.BlogMapper;
import com.lin.vo.User;

public class Test {
	public static void main(String[] args) {
		InputStream input =Test.class.getClassLoader().getResourceAsStream("conf.xml");
		SqlSessionFactory sessionFactory =new SqlSessionFactoryBuilder().build(input);
		SqlSession session=sessionFactory.openSession();
		String sql ="com.lin.po.userMapper.getUser";
		User u =session.selectOne(sql, 1);
		
		System.out.print(u);
		
		//两个配置文件的操作
		
//		InputStream input=Test.class.getClassLoader().getResourceAsStream("conf.xml");
//		SqlSessionFactory sessionFactory =new SqlSessionFactoryBuilder().build(input);
//		SqlSession session =sessionFactory.openSession();
//		BlogMapper mapper =session.getMapper(BlogMapper.class);
//		User u =mapper.selectUser(3);
//		System.out.print(u);
		
	}
  

}