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：

 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：

 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：

 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。