Mybatis学习demo03-dao实现类方式

雨点打透心脏的1/2处 2022-11-28 00:47 145阅读 0赞

## 1、创建demo03的maven项目 ##

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## 2、把demo01的src目录下的内容拷贝过来 ##

在dao目录下新建实现包和实现类  
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package com.wan.dao.impl;
    
    import com.wan.dao.IUserDao;
    import com.wan.mybatis.User;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    
    import java.util.List;
    
    public class UserDaoImpl implements IUserDao {
        
    
    	//创建一个工厂对象作为参数
    	//使用UserDaoImpl代替构造函数
        private SqlSessionFactory factory;
        public UserDaoImpl(SqlSessionFactory factory){
        
            this.factory=factory;
        }
    
        public List<User>findAll(){
        
    
            //1.使用工厂创建SqlSession对象
            SqlSession session = factory.openSession();
            //2.使用session执行查询所有方法
            //通过命名空间namespace.方法名findAll
            List<User> users = session.selectList("com.wan.dao.IUserDao.findAll");
            session.close();
            //3.返回查询结果
            return users;
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NjA0NzI4NQ_size_16_color_FFFFFF_t_70_pic_center 2]

## 3、更改测试案例 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NjA0NzI4NQ_size_16_color_FFFFFF_t_70_pic_center 3]

package com.wan.test;
    
    import com.wan.dao.IUserDao;
    import com.wan.dao.impl.UserDaoImpl;
    import com.wan.mybatis.User;
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.List;
    
    public class MybatisTest {
        
        //    入门案例
        public static void main(String[] args) throws IOException {
        
            //  1.读取配置文件
            InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
            //  2.从 XML 中构建 SqlSessionFactory
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
            SqlSessionFactory factory = builder.build(in);
            //  3. 使用工厂创建dao对象
            IUserDao userDao = new UserDaoImpl(factory);
            //  4. 使用代理对象执行方法
            List<User> users = userDao.findAll();
            for (User user : users) {
        
                System.out.println(user);
    
            }
            //  5.释放资源
    
            in.close();
    
        }
    }

## 4、运行结果 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NjA0NzI4NQ_size_16_color_FFFFFF_t_70_pic_center 4]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NjA0NzI4NQ_size_16_color_FFFFFF_t_70_pic_center]: /images/20221124/8349890610cf4231a7a3680b54b546dd.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NjA0NzI4NQ_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221124/53db673739d543c2a7b49b403f4c9f28.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NjA0NzI4NQ_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221124/5660f46d9c7744ab8c9d82fb56f0fe72.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NjA0NzI4NQ_size_16_color_FFFFFF_t_70_pic_center 3]: /images/20221124/4db95ece4a834f089e220ed4db7095f5.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NjA0NzI4NQ_size_16_color_FFFFFF_t_70_pic_center 4]: /images/20221124/126679b11a5b406a9c9b70a06962237d.png