mybatis实现mapper代理模式的方式

今晚继续复习mybtis
以根据id值查询单条数据为例
编写SqlMapConfig.xml文件

编写失血模型对象：Product,最好字段名和数据库里面的字段名一直

/**** 
Title: Product
 * 
Description: 商品类失血模型
 *
 @author Alon *
  @date 2020年9月27日 下午6:51:57 
  * @version 1.0 */ 
 public class Product {
  private int p_id;
   private String name; 
   private int p_number;
    private double price; 
    private String add_time;
     public Product(int p_id, String name, int p_number, double price, String add_time) { 
     super();
      this.p_id = p_id; 
      this.name = name; 
      this.p_number = p_number; 
      this.price = price; 
      this.add_time = add_time; 
      }public Product() { 
        super();
       }
       public int getP_id() { 
       return p_id; }
       public void setP_id(int p_id) { 
       this.p_id = p_id; }public String getName() { return name; }
       public void setName(String name) { this.name = name; }
       public int getP_number() { 
       return p_number; }
       public void setP_number(int p_number) { this.p_number = p_number; }
       public double getPrice() { return price; }
       public void setPrice(double price) { this.price = price; }
       public String getAdd_time() { return add_time;
}
public void setAdd_time(String add_time) { this.add_time = add_time; }
@Override 
public String toString() { 
return "Product [p_id=" + p_id + ", name=" + name + ", p_number=" + p_number + ", price=" + price + ", add_time=" + add_time + "]"; } }

编写单个映射关系的sql.xml：product.xml

 

   
  
   SELECT * FROM t_product WHERE p_id = #{value}
    
     

编写java代码进行测试执行sql语句并得到结果

/**** 
Title: MybatisDemo1
 *
 
Description: 查询数据的demo
 *
  @author Alon 
  * @date 2020年9月27日 下午7:05:32 
  * * @version 1.0 */ 
  * public class MybatisDemo1 {
  *  public static void main(String[] args) throws IOException { 
  * new MybatisDemo1().queryById(); }
  * public void queryById() throws IOException {
  *  //1、读取到SqlMapConfig.xml文件的流 String path = "SqlMapConfig.xml"; 
  * InputStream config = Resources.getResourceAsStream(path);
//创建会话工厂,同时将SqlMapConfig.xml里面的数据放到工厂中 SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(config); 
//开启会话 SqlSession sqlSession = factory.openSession(); /** 第一个参数：要执行哪个sql语句的参数，一般命名空间.id值 * 第二个参数：传入填充#{value}的传入参数值。 */ 
Object obj = sqlSession.selectOne("test.findById", 1); System.out.println(obj); } }

进行模糊查询：查询出多条结果集

  SELECT * FROM t_product WHERE name like "%${value}%"  public void queryByName() throws Exception
{
 String path = "SqlMapConfig.xml"; //获取流对象 InputStream config = Resources.getResourceAsStream(path); //获取会话工厂 SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(config); //开启会话 SqlSession sqlSession = factory.openSession(); /** 因为执行结果有多条语句，那么必须使用selectList */ List