回车键（Enter键）进行快速判断

    在其位，谋其政。做一颗螺丝钉，就发挥螺丝钉稳稳当当的功能。做软件，为了尽可能地为用户着想，增强用户体验度，增添附加值，进一步做些努力。

    本文介绍我在机房收费系统中的回车键实现上下机操作。以VB.NET作示例，而回车键（Enter键）的判断代码在其他语法也是适用的。

判断回车键的代码为：e.KeyCode = Keys.Enter或e.keyCode = “13”

实例：

'输入卡号，回车键(“Enter”键)，上下机Private Sub txtCardID_KeyDown(sender As Object, e As KeyEventArgs) Handles txtCardID.KeyDownDim UpDown As String = vbNullDim i As Integer = 1Dim myList As List(Of Entity.MainEntity)Dim logon_en As New Entity.LogonEntityDim updoing_en As New Entity.MainEntityDim main_bll As New BLL.MainBLL'捕获界面卡号logon_en.CardID = txtCardID.Text.Trimlogon_en.State = "使用"myList = main_bll.select_doing()'调用查询注册表方法，传入注册表实体，返回注册表实体将原来的实体覆盖logon_en = main_bll.select_logon(logon_en)'判断泛型（实体集）中实体个数If myList.Count > 0 ThenDo While i < myList.Count Or i = myList.Countupdoing_en = myList.Item(i - 1)'核查“卡号”是否在【正在上机表】中If updoing_en.CardID = txtCardID.Text.Trim ThenUpDown = "Down"Exit DoEnd Ifi = i + 1LoopIf UpDown = "Down" Then'标记保持不变UpDown = "Down"ElseIf logon_en.CardID = txtCardID.Text.Trim Then'修改标记UpDown = "Up"Else'清空标记UpDown = "Null"End IfElse'【正在上机表】无数据，那就直接，试试“上机”，按正常“上机”的程序走UpDown = "Up"End If'如果单击的按钮为“Enter”键（回车键）If e.KeyCode = Keys.Enter ThenIf UpDown = "Up" ThenbtnUp_Click(sender, e)   '等价于 = 敲击“上机”按钮ElseIf UpDown = "Down" ThenbtnDown_Click(sender, e)   '等价于 = 敲击“下机”按钮End IfEnd IfEnd Sub

      本实例用到了按键代换，就是相当于按下A键，进行判断，在若符合条件a等价于按了A键；若符合条件b则等价于按了B键。