KeyedCollection<TKey, TItem>与IDictionary<TKey, TValue>的区别

Code
usingSystem;
usingSystem.Collections.Generic;
usingSystem.Text;
usingSystem.Collections.ObjectModel;

namespaceJSON
{
publicclassMemberMappingCollection:KeyedCollection<string,MemberMapping>
{
protectedoverridestringGetKeyForItem(MemberMappingitem)
{
returnitem.MappingName;
}

publicvoidAddMapping(MemberMappingmemberMapping)
{
if(Contains(memberMapping.MappingName))
{
//don'toverwriteexistingmappingwithignoredmapping
if(memberMapping.Ignored)
return;

MemberMappingexistingMemberMapping=this[memberMapping.MappingName];

if(!existingMemberMapping.Ignored)
{
thrownewJsonSerializationException(
string.Format(
"Amemberwiththename'{0}'alreadyexistson{1}.UsetheJsonPropertyAttributetospecifyanothername.",
memberMapping.MappingName,memberMapping.Member.DeclaringType));
}
else
{
//removeignoredmappingsoitcanbereplacedincollection
Remove(existingMemberMapping);
}
}

Add(memberMapping);
}
}
}

这样一个元素值以键值对形式存在的集合就诞生了，下面就举例如何使用这样的一个集合类：

比如有一个Person类：

[code]publicclassPerson
{
publicstringName
{
get;
set;
}

publicintAge
{
get;
set;
}

publicintSalary
{
get;
set;
}
}

privateMemberMappingCollectionCreateMemberMappings(TypeobjectType)
{
MemberInfo[]members=objectType.GetMembers();
foreach(MemberInfomemberinmembers)
{
stringmappedName;
MemberMappingmemberMapping=newMemberMapping(member.Name,member,ignored,readable,writable);
memberMappings.AddMapping(memberMapping);
}

returnmemberMappings;
}

//用处

//这样随便传入一个类型便可获得这个类型的成员以键值对形式存在的集合

MemberMappingCollectionmemberMappings=CreateMemberMappings(typeof(Person));