mybatis 使用

建立 dao  entity mybatis 三个包

dao 包中主要建立的是 实体类的接口

entity包中建立的是实体类（这里不对实体类进行实现）

mybatis中建立的是实体类接口的实现

2.下边分别看几个文件的具体内容

  实体类

package org.checkin.entity;

public class User {
    
    private  String userName;
    private  String password;
    
    public String GetUserName()
    {
        return this.userName;
    }
    
    public String GetPassword()
    {
        return this.password;
    }
    
    public void SetUserName(String newValue)
    {
        this.userName=newValue;
        
    }
    public void SetPassord(String newValue)
    {
       this.password=newValue;
    }
    
    
    
    

}

 实体类的接口

package org.checkin.dao;
import org.checkin.entity.User;
/**
 * @author Administrator
 *
 */

public interface UserMapper {
    
 /**
 * @param Id
 * @return
 */
public User GetUserById(String Id);
}

实体类接口的实现

<?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">  
    <!--这块等于dao接口的实现  namespace必须和接口的类路径一样-->  
<mapper namespace="org.checkin.dao.UserMapper">  
    <!-- findById必须和接口中的方法名一样  返回一个User  就是刚才的别名  如果不弄别名要连类路径一起写 麻烦-->  
    <select id="GetUserById" parameterType="string" resultType="User">  
        select name as userName, ClassId as password from test.stu where id=#{id} 
    </select>
</mapper>  

连接数据库 configuration.xml文件

<?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>  
<typeAliases>
<package name="org.checkin.entity"/>
</typeAliases>
    <environments default="development">  
        <environment id="development">  
            <transactionManager type="JDBC" />  
            <dataSource type="POOLED">  
                <property name="driver" value="com.mysql.jdbc.Driver" />  
                <property name="url" value="jdbc:mysql://localhost:3306/test?userUnicode=true&amp;characterEncoding=utf8" />  
                <property name="username" value="root" />  
                <property name="password" value="root" />  
            </dataSource>  
        </environment>  
    </environments>     

      
    <mappers>  
        <mapper resource="org/checkin/mybatis/UserMapper.xml" /> 
        
    </mappers>  
      
</configuration>   

数据库

package org.checkin.dao;

import java.io.IOException;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class DataBaseCon {
    public static SqlSessionFactory getSessionFactory() {  
        SqlSessionFactory sessionFactory = null;  
        String resource = "configuration.xml";  
        try {  
            sessionFactory = new SqlSessionFactoryBuilder().build(Resources  
                    .getResourceAsReader(resource));  
        } catch (IOException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }  
        return sessionFactory;  
    }  
}

test.java

import org.apache.ibatis.session.SqlSession;
import org.checkin.dao.DataBaseCon;
import org.checkin.dao.UserMapper;
import org.checkin.entity.User;


public class Test {

    @org.junit.Test
    public void test() {
        SqlSession sqlSession = DataBaseCon.getSessionFactory().openSession();  
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);  
        User user = userMapper.GetUserById("1");  
        System.out.println(user.GetUserName());  
    }
    
    

}

数据库表