1：from窗体环境：TextBox(关键词文本框)、ListBox(提示框)

2：实现思路：

   2.1：以输入的关键词为条件查询  数据库（在查询中以点击率排序就加一个order by 点击率 desc）返回多行单列数据结果集合。再一一赋值到listBox中显示。

   2.2：在TextBox中如果侦听键盘

            if(Down（小键盘向下）)

                  则先获取到ListBox选中的索引，如果返回-1 或者x+1的值大于ListBox.count()   则初始值=0; 否则为ListBox索引值为x+1

          else (Up(小键盘向上))

               则先获取到ListBox选中的索引，如果返回-1 或者x-1的值< 0      则初始值=ListBox.count() ; 否则为ListBox索引值为x-1;

3：窗体代码如下

using System;using System.Collections.Generic;using System.Drawing;using System.Windows.Forms;using System.Threading;using System.IO;using System.IO.Ports;using System.Text.RegularExpressions;using System.Text;/// <summary>///     <author>hubiao</author>///	<date>2014-07-30</date>/// </summary>namespace ee{	/// <summary>	/// Description of MainForm.	/// </summary>	public partial class MainForm : Form	{		private List<String> dataBuffer = new List<String>();		public MainForm()		{			InitializeComponent();			//程序与from窗体分离执行			Control.CheckForIllegalCrossThreadCalls = false;		}		void Button1Click(object sender, System.EventArgs e)		{			textBox1.Text = String.Empty;		}		//这里可以从数据库初始化值		void MainFormLoad(object sender, EventArgs e)		{			dataBuffer.Add("心态");			dataBuffer.Add("信心");			dataBuffer.Add("能核心");			dataBuffer.Add("醉心能");			dataBuffer.Add("linuax");			dataBuffer.Add("linuax改变IT世界");			dataBuffer.Add("java");			dataBuffer.Add("java是点亮星星之火");			dataBuffer.Add("linaux改变IT世界");			dataBuffer.Add("java");			dataBuffer.Add("java是星星");			dataBuffer.Add("湖北省");			dataBuffer.Add("湖北跨省");			dataBuffer.Add("湖北武汉");			dataBuffer.Add("咸宁也是湖北的");			dataBuffer.Add("这是核桃");			dataBuffer.Add("通城属于咸宁的");			dataBuffer.Add("今天是星期几？");			//先隐藏！			listBox1.Hide();		}		//检索出值		bool isFjty = false;		void TextBox2TextChanged(object sender, EventArgs e)		{			TextBox tb = sender as TextBox;			if(isFjty)				return;						String outStr = tb.Text;			if(outStr==""){				listBox1.Hide();				return;			}else				listBox1.Show();			listBox1.Items.Clear();			foreach(String db in dataBuffer)			{				/*方案1：包含提示  				if(db.IndexOf(outStr)!=-1)				{					listBox1.Items.Add(db);				}*/				/*方案2：从前向后匹配				if(db.StartsWith(outStr))				{					listBox1.Items.Add(db);				}*/			}						int count = listBox1.Items.Count;			if(count > 0)				listBox1.Height = (count+1)*13;			else				TextBox2Leave(null,null);		}		Keys keys;		void ListBox1KeyDown(object sender, KeyEventArgs e)		{			keys = e.KeyCode;			textBox1.AppendText("key="+keys);		}		void TextBox2KeyUp(object sender, KeyEventArgs e)		{			Keys keys = e.KeyCode;			textBox1.Text = keys.ToString();			if(keys.ToString()=="Down" && listBox1.Items.Count > 0){				isFjty = true;				int x = listBox1.SelectedIndex;				x = x==-1?0:x+1;				if(x > listBox1.Items.Count-1)					x = 0;				listBox1.SelectedIndex = x;				textBox2.Text = listBox1.Items[x].ToString();				textBox2.SelectionStart = textBox2.Text.Length+1;			}else if(keys.ToString()=="Up" && listBox1.Items.Count > 0){				isFjty = true;				int x = listBox1.SelectedIndex;				int len = listBox1.Items.Count-1;				x = x==-1?len:x-1;				if(x < 0)					x = len;				listBox1.SelectedIndex = x;				textBox2.Text = listBox1.Items[x].ToString();				textBox2.SelectionStart = textBox2.Text.Length+1;			}else{				isFjty = false;			}		}		/*按下键时，如果不是上下移动，则立即侦听输入的字符*/		void TextBox2KeyDown(object sender, KeyEventArgs e)		{			if(keys.ToString()!="Down" || keys.ToString()!="Up")			{				isFjty = false;			}		}		/*鼠标手动选择*/		void ListBox1Click(object sender, EventArgs e)		{			textBox2.Text = listBox1.Items[listBox1.SelectedIndex].ToString();			textBox2.SelectionStart = textBox2.Text.Length+1;			textBox2.Focus();						//手动选择后，是否应该隐藏掉提示列表呢？			//TextBox2Leave(null,null);		}				//关键输入框失去焦点后就【隐藏提示列表】。		void TextBox2Leave(object sender, EventArgs e)		{			listBox1.Items.Clear();			listBox1.Height = 0;			listBox1.Hide();		}	}}

|--从前向后匹配

|--模糊匹配