一般來說，在.net中可以使用Type.GetCustomAttributes獲取類上的自定義屬性，可以使用PropertyInfo.GetCustomAttributes獲取屬性信息上的自定義屬性。

下面以定義一個(gè)簡單數(shù)據(jù)庫表的映射實(shí)體類來說明相關(guān)的使用方法,基于自定義類屬性和自定義類中的屬性的自定義屬性，可以方便的進(jìn)行類標(biāo)記和類中屬性的標(biāo)記

創(chuàng)建一個(gè)類的自定義屬性，用于標(biāo)識數(shù)據(jù)庫中的表名稱，需要繼承自Attribute類：

代碼如下:

[AttributeUsage(AttributeTargets.Class, Inherited = false, AllowMultiple = false)]

public sealed class TableAttribute : Attribute

{

private readonly string _TableName = "";

public TableAttribute(string tableName)

{

this._TableName = tableName;

}

public string TableName

{

get { return this._TableName; }

}

}

創(chuàng)建一個(gè)屬性的自定義屬性,用于標(biāo)識數(shù)據(jù)庫表中字段的名稱，需要繼承自Attribute類：

代碼如下:

[AttributeUsage(AttributeTargets.Property, Inherited = false, AllowMultiple = false)]

public class FieldAttribute : Attribute

{

private readonly string _FieldName = ""; ///數(shù)據(jù)庫的字段名稱

private System.Data.DbType _Type = System.Data.DbType.String; ///數(shù)據(jù)庫的字段類型

public FieldAttribute(string fieldName)

{

this._FieldName=fieldName;

}

public FieldAttribute(string fieldName,System.Data.DbType type)

{

this._FieldName=fieldName;

this._Type=type;

}

public string FieldName

{

get { return this._FieldName; }

}

public System.Data.DbType Type

{

get{return this._Type;}

}

}

創(chuàng)建一個(gè)數(shù)據(jù)實(shí)體基類：

代碼如下:

public class BaseEntity

{

public BaseEntity()

{

}

/// <summary>

/// 獲取表名稱

/// </summary>

/// <returns></returns>

public string GetTableName()

{

Type type = this.GetType();

object[] objs = type.GetCustomAttributes(typeof(TableAttribute), true);

if (objs.Length <= 0)

{

throw new Exception("實(shí)體類沒有標(biāo)識TableAttribute屬性");

}

else

{

object obj = objs[0];

TableAttribute ta = (TableAttribute)obj;

return ta.TableName; //獲取表名稱

}

}

/// <summary>

/// 獲取數(shù)據(jù)實(shí)體類上的FieldAttribute

/// </summary>

/// <param name="propertyName"></param>

/// <returns></returns>

public FieldAttribute GetFieldAttribute(string propertyName)

{

PropertyInfo field = this.GetType().GetProperty(propertyName);

if (field == null)

{

throw new Exception("屬性名" + propertyName + "不存在");

}

object[] objs = field.GetCustomAttributes(typeof(FieldAttribute), true);

if (objs.Length <= 0)

{

throw new Exception("類體屬性名" + propertyName + "沒有標(biāo)識FieldAttribute屬性");

}

else

{

object obj = objs[0];

FieldAttribute fieldAttribute=(FieldAttribute)obj;

fieldAttribute.FieldValue=field.GetValue(this,null);

return fieldAttribute;

}

}

}

創(chuàng)建數(shù)據(jù)實(shí)體：

代碼如下:

[Table("Wincms_Dictionary")] ///映射到數(shù)據(jù)庫的Wincms_Dictionary表

public class Wincms_Dictionary : BaseEntity

{

private int _DictionaryId;

public Wincms_Dictionary()

{

}

[Field("DictionaryId",DbType.Int32)] ///映射到數(shù)據(jù)庫的Wincms_Dictionary表中的字段

public int DictionaryId

{

get { return this._DictionaryId; }

set

{

this._DictionaryId = value;

}

}

}

///基于實(shí)體類獲取實(shí)體對應(yīng)的表名稱和字段名稱

public class Test

{

public static void main(string[] args)

{

Wincms_Dictionary dict=new Wincms_Dictionary();

Console.WriteLine("表名稱："+GetTableName(dict));

Console.WriteLine("字段名稱:"+GetFieldName(dict,"DictionaryId"));

Console.Read();

}

///獲取實(shí)體表名稱

public static string GetTableName(BaseEntity entity)

{

return entity.GetTableName();

}

///獲取實(shí)體字段名稱

public static string GetFieldName(BaseEntity entity,string propertyName)

{

FieldAttribute fieldAttribute=entity.GetFieldAttribute(propertyName);

return fieldAttribute.FieldName;

}

}

輸出結(jié)果為：

代碼如下:

表名稱：Wincms_Dictionary

字段名稱：DictionaryId

更多信息請查看IT技術(shù)專欄