c#深拷贝的一个方法

使用ef，有时候会遇到，要对一个对象进行拷贝复制，可是一般的方法，拷贝后会提示此对象的实例在上下文的 entitystate已经存在，就需要用一种拷贝。
简单的拷贝只拷贝了值类型，对引用类型的拷贝需要使用递归，依次循环到底。
public object Copy(object obj) {
 
            Object targetDeepCopyObj;
            try {
 
 
 
                Type targetType = obj.GetType();
                //值类型  
                if (targetType.IsValueType == true) {
                    targetDeepCopyObj = obj;
                }
                    //引用类型   
                else {
                    targetDeepCopyObj = System.Activator.CreateInstance(targetType);   //创建引用对象   
                    System.Reflection.MemberInfo[] memberCollection = obj.GetType().GetMembers();
 
                    foreach (System.Reflection.MemberInfo member in memberCollection) {
                        if (member.MemberType == System.Reflection.MemberTypes.Field) {
                            System.Reflection.FieldInfo field = (System.Reflection.FieldInfo)member;
                            Object fieldValue = field.GetValue(obj);
                            if (fieldValue is ICloneable) {
                                field.SetValue(targetDeepCopyObj, (fieldValue as ICloneable).Clone());
                            } else {
                                field.SetValue(targetDeepCopyObj, Copy(fieldValue));
                            }
 
                        } else if (member.MemberType == System.Reflection.MemberTypes.Property) {
                            System.Reflection.PropertyInfo myProperty = (System.Reflection.PropertyInfo)member;
                            MethodInfo info = myProperty.GetSetMethod(false);
                            if (info != null) {
                                object propertyValue = myProperty.GetValue(obj, null);
                                if (propertyValue is ICloneable) {
                                    myProperty.SetValue(targetDeepCopyObj, (propertyValue as ICloneable).Clone(), null);
                                } else {
                                    myProperty.SetValue(targetDeepCopyObj, Copy(propertyValue), null);
                                }
                            }
 
                        }
                    }
                }
                return targetDeepCopyObj;
            } catch (Exception e) {
 
            }
 
            return null;
        }