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1. 定义一个以Attribute结尾的特性类, 特性类继承自System.Attribute, 如下所示.
?[AttributeUsage(AttributeTargets.Property, AllowMultiple=false)]
?public class PrimaryKeyAttribute : System.Attribute
?{
??? .............
?
?
其中AttributeTargets是一个枚举的值, 可以是: Assembly | Module | Class | Struct | Enum | Constructor | Method | Property | Field | Event | Interface | Parameter | Delegate
?
2. 在需要使用的地方使用PrimaryKey自定义特性标签, 如下所示.
?[PrimaryKey(Column = "CustomerID", IsIdentity=false)]
??public int ID
??{
??????? .............
?
3. 为了获取自定义特性的信息, 需要反射的方式获取其数据, 首先我们定义一个类来存储这些信息, 如下所示
?public class PrimaryKeyModel
?{
??private readonly PropertyInfo propertyInfo;//外键的属性字段信息
??private readonly PrimaryKeyAttribute primaryKeyAtt;//外键的特性信息
? ................
?
??public static PrimaryKeyModel GetPrimaryKey(Type type)
??{
???PropertyInfo[] properties = type.GetProperties();
???foreach (PropertyInfo p in properties)
???{
????object[] keys = p.GetCustomAttributes(typeof(PrimaryKeyAttribute), true);
????if (keys.Length == 1)
????{
?????return new PrimaryKeyModel(p, keys[0] as PrimaryKeyAttribute);
????}
???}
???return null;
??}
?
4. 在Customer类中获取其特性的信息代码如下
???string strReturn = string.Empty;????
???//Get PrimaryKey Name
???PrimaryKeyModel attribute= PrimaryKeyModel.GetPrimaryKey(this.GetType());
???if(attribute != null)
???{
????strReturn += string.Format("PrimaryKey Name:{0} IsIdentity:{1} Column:{2}\r\n",
?????attribute.Property.Name, attribute.PrimaryKeyAtt.IsIdentity, attribute.PrimaryKeyAtt.Column);
???}
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