Lucene2.3.1搜索单个字母的时候出不来结果

如题，请高手帮忙，谢谢
代码如下：
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Documents;
using Lucene.Net.Index;
using Lucene.Net.QueryParsers;
using Lucene.Net.Search;
using System.IO;
using System.Collections.Generic;

public partial class Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            IndexInfo();

            Analyzer analyzer = new WhitespaceAnalyzer();

            IndexSearcher searcher = new IndexSearcher(Server.MapPath("IndexDirectory"));
            MultiFieldQueryParser parser = new MultiFieldQueryParser(new string[] { "title", "content" }, analyzer);
            Query query = parser.Parse("s");
            Hits hits = searcher.Search(query);

            for (int i = 0; i < hits.Length(); i++)
            {
                Document doc = hits.Doc(i);

                Response.Write(string.Format("title:{0} content:{1}", doc.Get("title"), doc.Get("content")));
            }
            searcher.Close();
        }
    }

    protected void IndexInfo()
    {
        Analyzer analyzer = new StandardAnalyzer();
        IndexWriter writer = new IndexWriter(Server.MapPath("IndexDirectory"), analyzer, true);
        AddDocument(writer, "SQL Server 2008 的发布", "SQL Server2008 的新特性");
        AddDocument(writer, "ASP.NetSQL MVC框架配置与分析2008", "而今，微软推出了新的MVC开发框架，也就是MicrosoftSQL ASP.NET2008 3.5 Extensions");
        writer.Optimize();
        writer.Close();
    }

    protected void AddDocument(IndexWriter writer, string title, string content)
    {
        Document document = new Document();
        document.Add(new Field("title", title, Field.Store.YES, Field.Index.TOKENIZED));
        document.Add(new Field("content", content, Field.Store.YES, Field.Index.TOKENIZED));
        writer.AddDocument(document);
    }
} --------------------编程问答-------------------- http://qq497525725.download.csdn.net/

这里有一个中文分词的例子。 --------------------编程问答-------------------- 无语。。

补充：.NET技术 ,  C#