winform 实现TextBox 关键字智能提示

　　有时候由于项目需求的需要，需要实现像百度那样输入关键字后有下拉框提示，在网上搜了下，一种是利用ComboBox和TextBox的AutoCompleteMode属性，个人感觉不太灵活，关键字只能从第一个字符开始匹配，不能实现任意位置的匹配和多个关键字的匹配；另外一一种方法是重写listbox 感觉太复杂……

　　最后我自己想了个比较简单，灵活的方法：

　　使用listBox的DrawMode.OwnerDrawFixed属性，设置ItemHeight=30，添加listBox1_DrawItem事件

   private static readonly string ConnectionString = ConfigurationManager.ConnectionStrings["SQLConnString"].ConnectionString;
        private void Form1_Load(object sender, EventArgs e)
        {
            listBox1.DrawMode = DrawMode.OwnerDrawFixed;
            listBox1.ItemHeight = 30;

        }

  private void listBox1_DrawItem(object sender, DrawItemEventArgs e)
        {
            // Set the DrawMode property to draw fixed sized items.
            listBox1.DrawMode = DrawMode.OwnerDrawFixed;
            // Draw the background of the ListBox control for each item.
            e.DrawBackground();
            // Define the default color of the brush as black.
            Brush myBrush = Brushes.Black;
            FontFamily fontFamily = new FontFamily("宋体");

            System.Drawing.Font myFont = new Font(fontFamily, 20);

            // Determine the color of the brush to draw each item based on the index of the item to draw





.

            if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
            {
                //e.Graphics.FillRectangle(Brushes.Blue, e.Bounds);
                if (e.Index > -1)
                {
                    e.Graphics.DrawString(listBox1.Items[e.Index].ToString(), myFont, Brushes.White, e.Bounds, StringFormat.GenericDefault);
                }

            }
            else
            {
                //e.Graphics.FillRectangle(Brushes.White, e.Bounds);
                if (e.Index > -1)
                {
                    e.Graphics.DrawString(listBox1.Items[e.Index].ToString(), myFont, myBrush, e.Bounds, StringFormat.GenericDefault);
                }

            }
            e.DrawFocusRectangle();

        }

    以SQL Server2005示例数据库AdventureWorks为例，添加textBox1_TextChanged事件，获取输入关键字，通过模糊查询将数据库中的相关信息绑定到下拉框listBox1中：

       private void BindList(DataTable dt)
        {
            this.listBox1.Items.Clear();

            for (int i = 0; i < dt.Rows.Count; i++)
            {
                listBox1.Items.Add(dt.Rows[i]["name"].ToString());

            }

            if (dt.Rows.Count < 11)
            {
                this.listBox1.Height = 30 * dt.Rows.Count + 30;
            }
            else
            {
                this.listBox1.Height = 300;
            }



            this.listBox1.Visible = true;
        }


        private DataTable getDataTable(string s)
        {
            string sql = @" SELECT Name FROM   Person.CountryRegion where [Name] like '%" + s.Trim() + "%' ";

            string strErr = "";
            DataTable dt = new DataTable();

            RunSQL(sql, null, out dt, out strErr);
            return dt;

        }

        public static bool RunSQL(string strSQL, SqlParameter[] para, out DataTable objDataTable, out string strErr)
        {
            objDataTable = new DataTable();

            strErr = "";

            using (SqlConnection conn = new SqlConnection(ConnectionString))
            {

                SqlCommand sqlComm = new SqlCommand(strSQL, conn);
                sqlComm.CommandType = CommandType.Text;

                if (para != null)
                {
                    foreach (SqlParameter parm in para)
                    {
                        if ((parm.Direction == ParameterDirection.InputOutput || parm.Direction == ParameterDirection.Input) &&
                                (parm.Value == null))
                        {
                            parm.Value = DBNull.Value;
                        }

                        sqlComm.Parameters.Add(parm);
                    }
                }

                SqlDataAdapter sqlDa = new SqlDataAdapter();
                try
                {
                    sqlDa.SelectCommand = sqlComm;
                    sqlDa.Fill(objDataTable);
                    sqlComm.Parameters.Clear();
                    return true;

                }
                catch (Exception ex)
                {
                    strErr = ex.Message;
                    return false;
                }
                finally
                {
                    if (sqlComm != null)
                    {
                        sqlComm.Dispose();
                    }
                    if (sqlDa != null)
                    {
                        sqlDa.Dispose();
                    }
                }
            }
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            if (this.textBox1.Text.Trim() != "")
            {
                DataTable dt = getDataTable(this.textBox1.Text.Trim());
                BindList(dt);
                this.listBox1.Visible = true;
            }
            else
            {
                this.listBox1.Items.Clear();
                this.listBox1.Visible = false;
            }
        }

在listBox1显示关键字的匹配结果时，先将 this.listBox1.Visible = false;当有匹配结果时置为true，就可以实现当关键字有匹配项时出现下拉提示，没有时隐藏，然后定义listbox和textbox的鼠标事件，使鼠标经过时变色，效果就跟百度的下拉提示一样了

  private void listBox1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter && this.listBox1.Visible && this.listBox1.SelectedItems.Count > 0)
            {
                this.textBox1.Text = this.listBox1.SelectedItems[0].ToString();

                this.listBox1.Visible = false;
                this.textBox1.Focus();
            }
        }

        private void textBox1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Down && this.listBox1.Visible)
            {
                this.listBox1.Focus();

                if (this.listBox1.SelectedItems.Count > 0)
                {
                    this.listBox1.SetSelected(this.listBox1.SelectedIndex, false);
                }

                if (this.listBox1.Items.Count > 0)
                {
                    this.listBox1.SetSelected(0, true);

                }


            }
        }

        private void listBox1_MouseUp(object sender, MouseEventArgs e)
        {
            if (this.listBox1.SelectedItems.Count > 0)
            {
                this.textBox1.Text = this.listBox1.SelectedItems[0].ToString();

                this.listBox1.Visible = false;
                this.textBox1.Focus();
            }
        }


        private void listBox1_MouseMove(object sender, MouseEventArgs e)
        {
            Point m = new Point(e.X, e.Y);

            int index = GetItemAt(this.listBox1, e.X, e.Y);
            if (this.listBox1.SelectedItems.Count > 0 && this.listBox1.SelectedIndex != index)
            {

                this.listBox1.SetSelected(this.listBox1.SelectedIndex, false);
            }
            if (index != -1 && this.listBox1.SelectedIndex != index)
            {

                this.listBox1.SetSelected(index, true);
            }


        }

        private int GetItemAt(ListBox listBox, int X, int Y)
        {
            int index = -1;
            for (int i = 0; i < listBox.Items.Count; i++)
            {
                System.Drawing.Rectangle r = listBox.GetItemRectangle(i);
                if (r.Contains(new Point(X, Y)))
                {
                    index = i;
                    break;
                }
            }
            return index;
        }

最后的效果：

  

  

 

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