一般来说，在.net中可以使用Type.GetCustomAttributes获取类上的自定义属性，可以使用PropertyInfo.GetCustomAttributes获取属性信息上的自定义属性。
下面以定义一个简单数据库表的映射实体类来说明相关的使用方法,基于自定义类属性和自定义类中的属性的自定义属性，可以方便的进行类标记和类中属性的标记
创建一个类的自定义属性，用于标识数据库中的表名称，需要继承自Attribute类：
复制代码代码如下:
[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; }
}
}
public sealed class TableAttribute : Attribute
{
private readonly string _TableName = "";
public TableAttribute(string tableName)
{
this._TableName = tableName;
}
public string TableName
{
get { return this._TableName; }
}
}
创建一个属性的自定义属性,用于标识数据库表中字段的名称，需要继承自Attribute类：
复制代码代码如下:
[AttributeUsage(AttributeTargets.Property, Inherited = false, AllowMultiple = false)]
public class FieldAttribute : Attribute
{
private readonly string _FieldName = ""; ///数据库的字段名称
private System.Data.DbType _Type = System.Data.DbType.String; ///数据库的字段类型
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;}
}
}
public class FieldAttribute : Attribute
{
private readonly string _FieldName = ""; ///数据库的字段名称
private System.Data.DbType _Type = System.Data.DbType.String; ///数据库的字段类型
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;}
}
}
创建一个数据实体基类：
复制代码代码如下:
public class BaseEntity
{
public BaseEntity()
{
}
/// <summary>
/// 获取表名称
/// </summary>
/// <returns></returns>
public string GetTableName()
{
Type type = this.GetType();
object[] objs = type.GetCustomAttributes(typeof(TableAttribute), true);
if (objs.Length <= 0)
{
throw new Exception("实体类没有标识TableAttribute属性");
}
else
{
object obj = objs[0];
TableAttribute ta = (TableAttribute)obj;
return ta.TableName; //获取表名称
}
}
/// <summary>
/// 获取数据实体类上的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("属性名" + propertyName + "不存在");
}
object[] objs = field.GetCustomAttributes(typeof(FieldAttribute), true);
if (objs.Length <= 0)
{
throw new Exception("类体属性名" + propertyName + "没有标识FieldAttribute属性");
}
else
{
object obj = objs[0];
FieldAttribute fieldAttribute=(FieldAttribute)obj;
fieldAttribute.FieldValue=field.GetValue(this,null);
return fieldAttribute;
}
}
}
{
public BaseEntity()
{
}
/// <summary>
/// 获取表名称
/// </summary>
/// <returns></returns>
public string GetTableName()
{
Type type = this.GetType();
object[] objs = type.GetCustomAttributes(typeof(TableAttribute), true);
if (objs.Length <= 0)
{
throw new Exception("实体类没有标识TableAttribute属性");
}
else
{
object obj = objs[0];
TableAttribute ta = (TableAttribute)obj;
return ta.TableName; //获取表名称
}
}
/// <summary>
/// 获取数据实体类上的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("属性名" + propertyName + "不存在");
}
object[] objs = field.GetCustomAttributes(typeof(FieldAttribute), true);
if (objs.Length <= 0)
{
throw new Exception("类体属性名" + propertyName + "没有标识FieldAttribute属性");
}
else
{
object obj = objs[0];
FieldAttribute fieldAttribute=(FieldAttribute)obj;
fieldAttribute.FieldValue=field.GetValue(this,null);
return fieldAttribute;
}
}
}
创建数据实体：
复制代码代码如下:
[Table("Wincms_Dictionary")] ///映射到数据库的Wincms_Dictionary表
public class Wincms_Dictionary : BaseEntity
{
private int _DictionaryId;
public Wincms_Dictionary()
{
}
[Field("DictionaryId",DbType.Int32)] ///映射到数据库的Wincms_Dictionary表中的字段
public int DictionaryId
{
get { return this._DictionaryId; }
set
{
this._DictionaryId = value;
}
}
}
///基于实体类获取实体对应的表名称和字段名称
public class Test
{
public static void main(string[] args)
{
Wincms_Dictionary dict=new Wincms_Dictionary();
Console.WriteLine("表名称："+GetTableName(dict));
Console.WriteLine("字段名称:"+GetFieldName(dict,"DictionaryId"));
Console.Read();
}
///获取实体表名称
public static string GetTableName(BaseEntity entity)
{
return entity.GetTableName();
}
///获取实体字段名称
public static string GetFieldName(BaseEntity entity,string propertyName)
{
FieldAttribute fieldAttribute=entity.GetFieldAttribute(propertyName);
return fieldAttribute.FieldName;
}
}
public class Wincms_Dictionary : BaseEntity
{
private int _DictionaryId;
public Wincms_Dictionary()
{
}
[Field("DictionaryId",DbType.Int32)] ///映射到数据库的Wincms_Dictionary表中的字段
public int DictionaryId
{
get { return this._DictionaryId; }
set
{
this._DictionaryId = value;
}
}
}
///基于实体类获取实体对应的表名称和字段名称
public class Test
{
public static void main(string[] args)
{
Wincms_Dictionary dict=new Wincms_Dictionary();
Console.WriteLine("表名称："+GetTableName(dict));
Console.WriteLine("字段名称:"+GetFieldName(dict,"DictionaryId"));
Console.Read();
}
///获取实体表名称
public static string GetTableName(BaseEntity entity)
{
return entity.GetTableName();
}
///获取实体字段名称
public static string GetFieldName(BaseEntity entity,string propertyName)
{
FieldAttribute fieldAttribute=entity.GetFieldAttribute(propertyName);
return fieldAttribute.FieldName;
}
}
输出结果为：
复制代码代码如下:
表名称：Wincms_Dictionary
字段名称：DictionaryId
字段名称：DictionaryId
希望本文所述对大家的.net程序设计有所帮助。
