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

 

代码

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

        }

 

 

 

代码

  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：

 

代码

       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

 

代码

  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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