自己动手写ORM框架(一):目标效果预览

    最终实现后达到的效果，只需写少量代码就可实现CURD操作。

DAL层代码：

StudentDAL代码

public   class StudentDAL
    {
        EntityManager entityManager =  EntityManagerFactory.CreateEntityManager();

        public StudentDAL() { }
        public StudentDAL(IDbTransaction transaction)
        {
            entityManager.Transaction = transaction;
        }

        public  List < StudentEntity > FindAll()
        {
            return entityManager.FindAll < StudentEntity > ();
        }
       
        public   int Save(StudentEntity entity)
        {
            return entityManager.Save(entity);
        }

        public   int Update(StudentEntity entity)
        {
            return entityManager.Update(entity);
        }

        public   int Remove(StudentEntity entity)
        {
            return entityManager.Remove(entity);
        }

        public   int Remove( object id)
        {
            return entityManager.Remove < StudentEntity > (id);
        }              

        public   List < StudentEntity > FindById( object id)
        {
            return entityManager.FindById < StudentEntity > (id);
        }

        public   List < StudentEntity > FindByProperty( string propertyName, object value)
        {
            return entityManager.FindByProperty < StudentEntity > (propertyName, value);
        }
    }

实体类与数据库表的映射关系配置：

StudentEntity代码

using System;
using System.Data;
using System.Collections.Generic;
using System.Text;
using System.Orm.CustomAttributes;

namespace Entity
{
    [Serializable]
    [Table(name = " Student " )]
    public   class  StudentEntity
    {
        private   string stuid;
        private   string stuno;
        private   string name;
        private   int sex;
        private   int age;
        private   string address;
        private   string telphone;

        [Id(Name=”stuid”,Strategy = GenerationType.SEQUENCE)]
        public   string Stuid
        {
            get { return stuid; }
            set { stuid = value; }
        }

        [Column(Name =   " studentno " )]
        public   string Stuno
        {
            get { return stuno; }
            set { stuno = value; }
        }

        [Column(IsInsert =   true )]
        public   string Name
        {
            get { return name; }
            set { name = value; }
        }

        [Column(IsUpdate =   true )]
        public   int Sex
        {
            get { return sex; }
            set { sex = value; }
        }

        public   int Age
        {
            get { return age; }
            set { age = value; }
        }
       
        public   string Address
        {
            get { return address; }
            set { address = value; }
        }
       
        public   string Telphone
        {
            get { return telphone; }
            set { telphone = value; }
        }
    }
}

BLL层代码：

StudentBLL代码

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using DAL;
using Entity;
using System.Orm.DBTransaction;

namespace BLL
{
    public   class  StudentBP
    {
        public  List < StudentEntity > FindAll()
        {
            StudentDAL dal =   new  StudentDAL();
            return dal.FindAll();
        }

        public   void Save(StudentEntity entity)
        {
            IDbTransaction trans =   null ;
            try
            {
                trans =  TransactionManager.CreateTransaction();
                StudentDAL dal =   new  StudentDAL(trans);
                dal.Save(entity);
                trans.Commit();

            }
            catch (Exception ex)
            {
                trans.Rollback();
                throw ex;
            }
            finally
            {
                trans.Dispose();
            }
        }

        public   void Remove( object id)
        {
            IDbTransaction trans =   null ;
            try
            {
                trans =  TransactionManager.CreateTransaction();
                StudentDAL dal =   new  StudentDAL(trans);
                dal.Remove(id);
                trans.Commit();

            }
            catch (Exception ex)
            {
                trans.Rollback();
                throw ex;
            }
            finally {
                trans.Dispose();
            }
        }       
    }
}

     在实体类中配置[Table(Name="Student")]，对应数据库中的表名：Student

     在实体类中配置[Id(Name=”studentid”,Strategy = GenerationType.SEQUENCE)]，表示当前属性是Student表中的主键ID，Name=”studentid”表示该属性Stuid对应Student表列studentid，Strategy表示主键生成策略，这里是自动增长。

     在实体类中配置[Column(Name="studentno")]，表示当前属性Stuno对应Student表中的列名：studentno(默认属性名=列名)

在实体类中配置[Column(IsInsert=false)]，表示当前列值不插入到数据库(默认插入)

在实体类中配置[Column(IsUpdate=false)]，表示当前列值不更新到数据库(默认更新)

(实体类映射配置和一些命名参考了JAVA中的JPA)

在下一篇中将开始研究如何一步一步的构建一个简单的ORM框架。