c#模仿百度關鍵詞提示

1：from窗體環境：TextBox(關鍵詞文本框)、ListBox(提示框)

2：實現思路：

2.1：以輸入的關鍵詞爲條件查詢數據庫（在查詢中以點擊率排序就加一個order by 點擊率 desc）返回多行單列數據結果集合。再一一賦值到listBox中顯示。

2.2：在TextBox中如果偵聽鍵盤

if(Down（小鍵盤向下）)

則先獲取到ListBox選中的索引，如果返回-1 或者x+1的值大於ListBox.count() 則初始值=0; 否則爲ListBox索引值爲x+1

else (Up(小鍵盤向上))

則先獲取到ListBox選中的索引，如果返回-1 或者x-1的值< 0 則初始值=ListBox.count() ; 否則爲ListBox索引值爲x-1;

3：窗體代碼如下

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();
			//程序與from窗體分離執行
			Control.CheckForIllegalCrossThreadCalls = false;
		}
		void Button1Click(object sender, System.EventArgs e)
		{
			textBox1.Text = String.Empty;
		}
		//這裏可以從數據庫初始化值
		void MainFormLoad(object sender, EventArgs e)
		{
			dataBuffer.Add("心態");
			dataBuffer.Add("信心");
			dataBuffer.Add("能核心");
			dataBuffer.Add("醉心能");
			dataBuffer.Add("linuax");
			dataBuffer.Add("linuax改變IT世界");
			dataBuffer.Add("java");
			dataBuffer.Add("java是點亮星星之火");
			dataBuffer.Add("linaux改變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("湖北武漢");
			dataBuffer.Add("咸寧也是湖北的");
			dataBuffer.Add("這是核桃");
			dataBuffer.Add("通城屬於咸寧的");
			dataBuffer.Add("今天是星期幾？");
			//先隱藏！
			listBox1.Hide();
		}
		//檢索出值
		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：從前向後匹配
				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;
			}
		}
		/*按下鍵時，如果不是上下移動，則立即偵聽輸入的字符*/
		void TextBox2KeyDown(object sender, KeyEventArgs e)
		{
			if(keys.ToString()!="Down" || keys.ToString()!="Up")
			{
				isFjty = false;
			}
		}
		/*鼠標手動選擇*/
		void ListBox1Click(object sender, EventArgs e)
		{
			textBox2.Text = listBox1.Items[listBox1.SelectedIndex].ToString();
			textBox2.SelectionStart = textBox2.Text.Length+1;
			textBox2.Focus();
			
			//手動選擇後，是否應該隱藏掉提示列表呢？
			//TextBox2Leave(null,null);
		}
		
		//關鍵輸入框失去焦點後就【隱藏提示列表】。
		void TextBox2Leave(object sender, EventArgs e)
		{
			listBox1.Items.Clear();
			listBox1.Height = 0;
			listBox1.Hide();
		}
	}
}

4：示例圖

|--從前向後匹配