一個較完整的關鍵字過濾解決方案（上）

需求：全站統一關鍵字過濾，避免逐處修改。HttpModule 是唯一選擇：在 BeginRequest 過濾 QueryString 與 Form 集合。初步實作：

public class FilterForbiddenWordModule : IHttpModule
{
    void IHttpModule.Init(HttpApplication context)
    {
        context.BeginRequest += OnBeginRequest;
    }
    static void OnBeginRequest(object sender, EventArgs e)
    {
        var request = (sender as HttpApplication).Request;
        ProcessCollection(request.QueryString);
        ProcessCollection(request.Form);
    }
    static void ProcessCollection(NameValueCollection collection)
    {
        var copy = new NameValueCollection();
        foreach (string key in collection.AllKeys)
            Array.ForEach(collection.GetValues(key), v => copy.Add(key, ForbiddenWord.Filter(v)));
        collection.Clear();
        collection.Add(copy);
    }
}

看似簡單，實則暗藏後續文章將揭示的陷阱。