我试图根据类的名称和通过反射存在自定义属性来获取类的某些字段的值。 我的自定义属性是：
[AttributeUsage (AttributeTargets.All, AllowMultiple=true)]
public sealed class ColumnAttribute : Attribute
{
internal string name = "";
internal string length = "";
internal string precision = "";
public ColumnAttribute() { }
public ColumnAttribute(String name) { this.name = name; }
public ColumnAttribute(String name, String length) { }
public ColumnAttribute(String name, String length, String precision) { }
public String Name { get { return name; } set { name = value; } }
public String Length { get { return length; } set { length = value; } }
public String Precision { get { return precision; } set { precision = value; } }
}
使用它的示例类是：
class SampleEntity
{
//private int number;
public string name;
//float marks;
public virtual int Number { get; set; }
public SampleEntity() { }
public SampleEntity(int number)
{
this.Number = number;
}
public void conversation(string request, string response) { }
public void ordinary() {
Console.Write("This isn't ordinary...");
}
[ColumnAttribute (Name = "XWBCCD")]
public String XWBCCD { get; set; }
[ColumnAttribute (Name = "XWBNCD")]
public String XWBNCD { get; set; }
我还有一个具有不同字段名称的不同类：
class SampleRepository
{
[ColumnAttribute(Name = "XWBCCD")]
public String SomeOtherFieldName { get; set; }
[ColumnAttribute(Name = "XWBNCD")]
public String XWBNCD { get; set; }
[ColumnAttribute(Name = "XWBWCD")]
public String XWBWCD { get; set; }
}
通过反射，我试图通过匹配属性'name'参数而不是fieldname来复制值。 麻烦的是，在反射过程中，通过遍历字段的getCustomAttributes（）方法不会发生这种比较。 我解决这个问题的方法（到目前为止失败了）是： 首先我传递2个对象，objSrc（第一类，已填充）和objDesc（第二类为空）
FieldInfo[] srcFields = objSrc.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance | BindingFlags.GetProperty | BindingFlags.IgnoreCase |BindingFlags.FlattenHierarchy);
FieldInfo[] destFields = objDest.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance | BindingFlags.GetProperty);
然后我试图在所有字段上迭代地执行反射
foreach (FieldInfo srcFld in srcFields)
{
foreach (FieldInfo destFld in destFields)
{
if (((MemberInfo)srcFld).Name.Equals(((MemberInfo)destFld).Name)){
destFld.SetValue(objDest, srcFld.GetValue(objSrc));
break;
}
object[] srcAttr = srcFld.GetCustomAttributes(true);
object[] destAttr = destFld.GetCustomAttributes(true);
if (Utils.Length(srcAttr) == 1 && Utils.Length(destAttr) == 1){
if ((srcAttr[0]).Equals(destAttr[0]) && srcFld.FieldType.Equals(destFld.FieldType))
destFld.SetValue(objDest, srcFld.GetValue(objSrc));
else
break;
}
}
}
GetCustomAttributes（）方法发生故障，因为它返回null。
答案 0 :(得分：0)
我为vb.net代码而不是c＃道歉，但我碰巧有一个linqpad文件，我在做同样的事情，在这里你走了：
（根本不是真正的生产就绪代码，但是我希望能得到这个想法。）
Sub Main
dim data as DataRow = GetSomeData.GetData(2311385).rows(0)
dim dm as IDataMapper = new DataMapper()
dim login as LoginData = dm.MapDataTo(of LoginData)(data)
data.Dump()
login.dump()
End Sub
public interface IDataMapper
function MapDataTo(of T as {IDataMappable,new})(data as DataRow) as T
end interface
public interface IDataMappable
end interface
public class DataMapper
implements IDataMapper
Public Function MapDataTo(Of T As {New, IDataMappable})(ByVal data As System.Data.DataRow) As T Implements IDataMapper.MapDataTo
dim mapToObj as new T
dim properties() as PropertyInfo = gettype(T).GetProperties()
for each propInfo as PropertyInfo in properties
Dim attributes() As Attribute = propInfo.GetCustomAttributes(GetType(DataMappingAttribute), True)
if attributes.length > 0 then
Dim dataAttribute As DataMappingAttribute = CType(attributes(0), DataMappingAttribute)
Dim column As String = dataAttribute.ColumnName
Dim dataType As Type = dataAttribute.DataType
propInfo.SetValue(mapToObj, Convert.ChangeType(data(column), dataType), Nothing)
end if
next
return mapToObj
end function
end class
<AttributeUsage(AttributeTargets.Property)> _
public class DataMappingAttribute
inherits Attribute
private _ColumnName as string
Public readonly Property ColumnName() As String
Get
return _ColumnName
End Get
End Property
private _DataType as Type
Public readonly Property DataType() As Type
Get
return _DataType
End Get
End Property
public sub new(ColumnName as string, DataType as Type)
me._columnName = ColumnName
me._DataType = DataType
end sub
end class
public class LoginData
implements IDataMappable
private _LoginID as integer
<DataMappingAttribute("loginID",Gettype(integer))> _
public property LoginID as integer
get
return _LoginID
end get
set(value as integer)
_LoginID = value
end set
end property
private _LoginName as string
<DataMappingAttribute("loginName",Gettype(String))> _
public property LoginName as string
get
return _LoginName
end get
set(value as string)
_LoginName = value
end set
end property
private _FirstName as string
<DataMappingAttribute("firstName",Gettype(String))> _
public property FirstName as string
get
return _FirstName
end get
set(value as string)
_FirstName = value
end set
end property
private _LastName as string
<DataMappingAttribute("lastName",Gettype(String))> _
public property LastName as string
get
return _LastName
end get
set(value as string)
_LastName = value
end set
end property
private _EmailAddress as string
<DataMappingAttribute("emailAddress",Gettype(String))> _
public property EmailAddress as string
get
return _EmailAddress
end get
set(value as string)
_EmailAddress = value
end set
end property
end class
public class GetSomeData
Public shared Function GetData(ByVal ID As Integer) As DataTable
'return a datatable
End Function
end class