实现Mybatis

介绍

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Mybatis 是通过jdk的动态代理和反射来实现mapper的方法构建的

环境准备

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下载和部署模型

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1. UserMapper

   public interface UserMapper {
    User selectUserById(@Param("id") int id);
   
    User selectByName(@Param("name") String name);
   
    User selectByNameAndAge(@Param("name") String name,@Param("age") int age);
    }
   

2. 参数注解 Param

   @Retention(RetentionPolicy.RUNTIME)
   @Target(ElementType.PARAMETER)
   public @interface Param {
       String value();
   }
   

3. 表名注解 Table

   @Retention(RetentionPolicy.RUNTIME)
   @Target(ElementType.TYPE)
   public @interface Table {
       String tableName();
   }
   

4. 测试

   public class App
   {
       public static void main(String[] args) {
           MySqlSessionFactory mySqlSessionFactory = new MySqlSessionFactory();
           UserMapper mapper = mySqlSessionFactory.getMapper(UserMapper.class);
           User user = mapper.selectUserById(1);
           System.out.println(user);
       }
   }
   

   select id,name,age from user where id =?
   User(id=1, name=测试1, age=10)