用自定义属性实现必需字段的检查

using  System;
using  System.Collections.Generic;
using  System.Text;
using  System.Reflection;
using  System.Diagnostics;
using  System.Windows.Forms;

namespace  desz
{
     ///   <summary>
     ///  这是我的第一个属性,测试文档,这个属性只能用于Field
     ///   </summary>
    [AttributeUsage(AttributeTargets.Field, Inherited  =   true )]
     public   class  cxyAttrib : System.Attribute
    {
         string  name;
         string  createdate;
         bool  IsRequired;

         public  cxyAttrib()
        {
        }
         public  cxyAttrib( string  t_date, string  t_name, bool  t_req)
        {
            createdate  =  t_date;
            name  =  t_name;
            IsRequired  =  t_req;
        }



         ///   <summary>
         ///  当前属性的名称
         ///   </summary>
         public   string  Name
        {
             get  {  return  name; }
             set  { name  =  value; }
        }
         ///   <summary>
         ///  创建日期
         ///   </summary>
         public   string  CreateDate
        {
             get  {  return  createdate; }
             set  { createdate  =  value; }
        }
         ///   <summary>
         ///  是否必须
         ///   </summary>
         public   bool  Required
        {
             get  {  return  IsRequired; }
             set  { IsRequired  =  value; }
        }

    }

     public   class  MyPeriseObject
    {
     // 在这里设置那一些字段是必须的,作为以后检查的根据
        [cxyAttrib(CreateDate  =   " 2007-10-9 " , Name  =   " object id " , Required  =   true )]
         private   string  id;
        [cxyAttrib(CreateDate  =   " 2007-10-8 " , Name  =   " object name " , Required  =   true )]
         private   string  name;
        [cxyAttrib(CreateDate  =   " 2007-10-7 " , Name  =   " object color " , Required  =   false )]
         private   string  color;

     // 以下的就是属性了
      
         public   string  ID
        {
             get  {  return  id; }
             set  { id  =  value; }
        }

       
         public   string  Name
        {
             get  {  return  name; }
             set  { name  =  value; }
        }

      
         public   string  Color
        {
             get  {  return  color; }
             set  { color  =  value; }
        } 

    }

     ///   <summary>
     ///  用来检查当前物体在持久化之前所有的属性是否都已经全部赋值了
     ///   </summary>
     public   class  CheckAttribute
    {
         public   static   void  Run()
        {
            MyPeriseObject componet1  =   new  MyPeriseObject();
            componet1.ID  =   " 100 " ;
            Type currentType  =  componet1.GetType();
            FieldInfo[] fi  =  currentType.GetFields(BindingFlags.NonPublic  |  BindingFlags.Instance); // 找出当前对type中有那些fields



             foreach  (FieldInfo tf  in  fi)
            {
         // 找出赋在这些field上的自定义属性
                cxyAttrib tpcxy  =  (cxyAttrib)Attribute.GetCustomAttribute(tf,  typeof (cxyAttrib));
                 if  (tpcxy  !=   null )
                     if  (tpcxy.Required)  // 检查设置时值是否是必须,并检查当前值是否是必须
                         if  (tf.GetValue(componet1)  ==   null )
                        {
                            Debug.WriteLine( " 必要属性没有被设置值 " );
                            MessageBox.Show(tf.Name  +   " 是一个必要属性 但是没有被设置值 " );
                        }
                         else
                        {
                            MessageBox.Show(tf.Name  +   " 的属性值是: "   +  tf.GetValue(componet1).ToString());
                        } 
            }

        }
    }
}