Cookie写入浏览器的过程：我们可以使用如下代码在Asp.net项目中写一个Cookie 并发送到客户端的浏览器(为了简单我没有设置其它属性)。
HttpCookie cookie = new HttpCookie("MyCookieName", "string value");
Response.Cookies.Add(cookie);
Response.Cookies.Add(cookie);
代码的关键点在于调用了Response.Cookies.Add()，我们来看看它们是如何实现的。首先来看Response.Cookies
public HttpCookieCollection Cookies
{
get
{
if (this._cookies == null)
{
this._cookies = new HttpCookieCollection(this, false);
}
return this._cookies;
}
}
{
get
{
if (this._cookies == null)
{
this._cookies = new HttpCookieCollection(this, false);
}
return this._cookies;
}
}
再来看HttpCookieCollection这个集合的实现：
public sealed class HttpCookieCollection : NameObjectCollectionBase
{
public HttpCookieCollection() : base(StringComparer.OrdinalIgnoreCase)
{
}
internal HttpCookieCollection(HttpResponse response, bool readOnly)
: base(StringComparer.OrdinalIgnoreCase)
{
this._response = response;
base.IsReadOnly = readOnly;
}
public void Add(HttpCookie cookie)
{
if (this._response != null)
{
this._response.BeforeCookieCollectionChange();
}
this.AddCookie(cookie, true);
if (this._response != null)
{
this._response.OnCookieAdd(cookie);
}
}
{
public HttpCookieCollection() : base(StringComparer.OrdinalIgnoreCase)
{
}
internal HttpCookieCollection(HttpResponse response, bool readOnly)
: base(StringComparer.OrdinalIgnoreCase)
{
this._response = response;
base.IsReadOnly = readOnly;
}
public void Add(HttpCookie cookie)
{
if (this._response != null)
{
this._response.BeforeCookieCollectionChange();
}
this.AddCookie(cookie, true);
if (this._response != null)
{
this._response.OnCookieAdd(cookie);
}
}
注意：由于在HttpResponse中创建HttpCookieCollection时，把HttpResponse对象传入了，因此，在调用HttpCookieCollection.Add()方法时，会调用HttpResponse的OnCookieAdd(cookie); 我们接着看：
internal void OnCookieAdd(HttpCookie cookie)
{
this.Request.AddResponseCookie(cookie);
}
{
this.Request.AddResponseCookie(cookie);
}
又转到Request对象的调用了，接着看
internal void AddResponseCookie(HttpCookie cookie)
{
if (this._cookies != null)
{
this._cookies.AddCookie(cookie, true);
}
if (this._params != null)
{
this._params.MakeReadWrite();
this._params.Add(cookie.Name, cookie.Value);
this._params.MakeReadOnly();
}
}
{
if (this._cookies != null)
{
this._cookies.AddCookie(cookie, true);
}
if (this._params != null)
{
this._params.MakeReadWrite();
this._params.Add(cookie.Name, cookie.Value);
this._params.MakeReadOnly();
}
}
从以上的代码分析中，我们可以看到，我们调用Response.Cookies.Add()时，Cookie也会加到HttpRequest.Cookies中。
而且，如果我们访问过程Request.Params[]，也会加到那个集合中。现在，您该明白了为什么当一个key有多个值时，为什么会用逗号分开来了吧。
或许，看到这里，您又有了一个新的想法：对于有多值的情况，还要我来按逗号拆分它们，太麻烦了，有没有不要拆分的方法呢?
答案是：有的，您可以访问NameValueCollection的GetValues方法，这个方法的实现如下：
public virtual string[] GetValues(string name)
{
ArrayList list = (ArrayList)base.BaseGet(name);
return GetAsStringArray(list);
}
private static string[] GetAsStringArray(ArrayList list)
{
int count = (list != null) ? list.Count : 0;
if( count == 0 ) {
return null;
}
string[] array = new string[count];
list.CopyTo(0, array, 0, count);
return array;
}
{
ArrayList list = (ArrayList)base.BaseGet(name);
return GetAsStringArray(list);
}
private static string[] GetAsStringArray(ArrayList list)
{
int count = (list != null) ? list.Count : 0;
if( count == 0 ) {
return null;
}
string[] array = new string[count];
list.CopyTo(0, array, 0, count);
return array;
}
