.NET Reflection 反射类属性间的拷贝

This code sample demonstrates how to copy class properties from one class to another even if they are not the same type. It also demonstrates how to validate a class's required properties dynamically. Both of these can increase your coding productivity especially when dealing with web service versions of your business classes.

PropertyHandler.cs
using System; using System.Collections.Generic; using System.Reflection; using System.Text; using System.Diagnostics; namespace MyApplication { public class PropertyHandler { #region Set Properties public static void SetProperties(PropertyInfo[] fromFields, PropertyInfo[] toFields, object fromRecord, object toRecord) { PropertyInfo fromField = null; PropertyInfo toField = null; try { if (fromFields == null) { return; } if (toFields == null) { return; } for (int f = 0; f < fromFields.Length; f++) { fromField = (PropertyInfo)fromFields[f]; for (int t = 0; t < toFields.Length; t++) { toField = (PropertyInfo)toFields[t]; if (fromField.Name != toField.Name) { continue; } toField.SetValue(toRecord, fromField.GetValue(fromRecord, null), null); break; } } } catch (Exception) { throw; } } #endregion #region Set Properties public static void SetProperties(PropertyInfo[] fromFields, object fromRecord, object toRecord) { PropertyInfo fromField = null; try { if (fromFields == null) { return; } for (int f = 0; f < fromFields.Length; f++) { fromField = (PropertyInfo)fromFields[f]; fromField.SetValue(toRecord, fromField.GetValue(fromRecord, null), null); } } catch (Exception) { throw; } } #endregion } }
PropertyHandler Sample For Identical Classes
MyClass record = new MyClass(); MyClass newRecord = new MyClass(); PropertyInfo[] fromFields = null; fromFields = typeof(MyClass).GetProperties(); PropertyHandler.SetProperties(fromFields, record, newRecord);
PropertyHandler Sample For Similar Classes
MyClass record = new MyClass(); MyOtherClass newRecord = new MyOtherClass(); PropertyInfo[] fromFields = null; PropertyInfo[] toFields = null; fromFields = typeof(MyClass).GetProperties(); toFields = typeof(MyOtherClass).GetProperties(); PropertyHandler.SetProperties(fromFields,toFields,record, newRecord);
Self Validation Methods
// Some of the code below relies on runtime reflection. Certain aspects // of reflection are detrimental to performance. Where possible, you // can create static instances of the reflection results. It will give // the power without the overhead of using reflection. // Here is a sample business class layer self validation method. private bool ValidateSave(CellAlignment record) { object[,] properties = null; List<string> returnMessages = new List<string>(); try { // Use the .GetFields() method mentioned later in this sample. properties = this.GetFields(this.GetType()); if (!record.ValidateRequiredProperties(properties, returnMessages)) { for (int i = 0; i < returnMessages.Count; i++) { Debug.WriteLine(returnMessages[i]); } return false; } } catch (Exception) { throw;} return true; } // This code was extracted from the ADO.NET Code Generator mentioned // above. // Here is a sample property to demonstrate how to use the // ColumnAttributes class. It sets this as being required // and tells the validator that it is an int data type. private int cellAlignmentID = 0; [ColumnAttributes("CellAlignmentID",true,"int")] public int CellAlignmentID { get { return cellAlignmentID; } set { if (value != cellAlignmentID) { cellAlignmentID = valuue; } } } // The ColumnAttributes class itself. [AttributeUsage(AttributeTargets.Property,AllowMultiple = true)] public sealed class ColumnAttributes : System.Attribute { private string columnName; private bool isRequired; private string propertyType; public string ColumnName { get { return columnName; } } public bool IsRequired { get { return isRequired; } } public string PropertyType { get { return propertyType; } } public ColumnAttributes(string columnNameValue, bool isRequiredValue, string propertyTypeValue) { columnName = columnNameValue; isRequired = isRequiredValue; propertyType = propertyTypeValue; } } // Here is a method we can use to get an array of // PropertyInfo objects as well as custom attributes. // Make sure every class has this in method available // to run on itself. The ADO.NET Code Generator has // this apart of the CustomAttributes.cs that all // DataObjects inherit. public object[,] GetFields(Type t) { PropertyInfo[] fields = t.GetProperties(); PropertyInfo field; Attribute[] attributes; object[,] structureInfo = new object[fields.Length,2]; try { for(int i =0;i<fields.Length;i++) { field = fields[i]; attributes = Attribute.GetCustomAttributes(field, typeof(DataObjects.Tables.ColumnAttributes), false); structureInfo[i,0] = field; structureInfo[i,1] = attributes; } } catch (Exception) { throw; } return structureInfo; } public bool ValidateRequiredProperties(object[,] properties, List<string> returnMessages) { bool returnValue = true; PropertyInfo property; Attribute[] attributes; ColumnAttributes columnAttribute = null; try { if (properties == null) { throw new Exception("Please pass in the results of this.GetFields()."); } if (returnMessages != null) { returnMessages.Clear(); } for (int i = 0; i <= properties.GetUpperBound(0); i++) { property = (PropertyInfo)properties[i, 0]; attributes = (Attribute[])properties[i, 1]; foreach (Attribute attribute in attributes) { columnAttribute = (ColumnAttributes)attribute; if (!columnAttribute.IsRequired) { continue; } // Debug.WriteLine(columnAttribute.ColumnName); // Debug.WriteLine(property.GetValue(this,null)); if (!this.ValidateRequiredPropertyInfo(columnAttribute, property)) { returnValue = false; if (returnMessages != null) { returnMessages.Add(columnAttribute.ColumnName + " is required."); } } } } } catch (Exception) { throw;} return returnValue; } public bool ValidateRequiredProperties(object[,] properties) { List<string> returnMessages = null; try { return ValidateRequiredProperties(properties, returnMessages); } catch (Exception) { throw; } } public bool ValidateRequiredPropertyInfo(ColumnAttributes columnAttribute, PropertyInfo property) { try { switch (columnAttribute.PropertyType.ToLower()) { case "int": if ((int)property.GetValue(this, null) == 0) { return false; } break; case "int16": if ((Int16)property.GetValue(this, null) == 0) { return false; } break; case "int32": if ((Int32)property.GetValue(this, null) == 0) { return false; } break; case "int64": if ((Int64)property.GetValue(this, null) == 0) { return false; } break; case "uint": if ((uint)property.GetValue(this, null) == 0) { return false; } break; case "uint16": if ((UInt16)property.GetValue(this, null) == 0) { return false; } break; case "uint32": if ((UInt32)property.GetValue(this, null) == 0) { return false; } break; case "uint64": if ((UInt64)property.GetValue(this, null) == 0) { return false; } break; case "double": if ((double)property.GetValue(this, null) == 0) { return false; } break; case "float": if ((float)property.GetValue(this, null) == 0) { return false; } break; case "single": if ((Single)property.GetValue(this, null) == 0) { return false; } break; case "string": if ((string)property.GetValue(this, null) == String.Empty) { return false; } break; case "guid": if ((Guid)property.GetValue(this, null) == Guid.Empty) { return false; } break; default: if (property.GetValue(this, null) == null) { return false; } break; } } catch (Exception) { throw; } return true; }