三层 之 充值

本文主要是介绍三层 之 充值，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

在三层的地方也炖了不少时间了，再炖就烂了，找好了时机，趁大家不注意，总结一下：

从上面的这幅导图中，就可以看到，由U层（表示层） 引用 B层（逻辑判断层）和 Entity（实体“层”），由 B层 引用 D层和实体层，由D层引用实体层，也就是

只能单向引用，不可反复

下面，还是由实例来说明耕层之间的关系：

充值之界面：

                     

充值之U层：

<pre name="code" class="vb">Public Class Form1Private Sub btnOK_Click(sender As Object, e As EventArgs) Handles btnOK.ClickTryDim eUser2 As New EntityRecharge.RechargeInfoDim eUser3 As EntityRecharge.RechargeInfoeUser2.IDcard = Trim(txtIDcard.Text)eUser2.AddCash = Trim(txtAddCash.Text)Dim mgr As New RechargeBLL.RechargeManagereUser3 = mgr.RechargeSc(eUser2)Catch ex As ExceptionMessageBox.Show(ex.Message.ToString())End TryEnd SubPrivate Sub btnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.ClickMe.Close()End Sub
End Class

充值之B层：

<pre name="code" class="vb">Public Class RechargeManagerPublic Function RechargeSc(ByVal User As RechargeInfo) As EntityRecharge.RechargeInfoDim rDAO As New RechargeDAL.RechargeDAODim eUser1 As BooleaneUser1 = rDAO.SelectUser(User)        '寻找卡号If eUser1 = False Then                '返回FALSE 代表  查找失败，也就是卡号未注册Throw New Exception("卡号不存在，充值失败")ElseeUser1 = rDAO.UpdateCash(User)     '查找成功，执行充值操作If eUser1 = True ThenMsgBox("充值成功")ElseThrow New Exception("充值失败")End IfEnd IfReturn UserEnd Function
End Class

充值之D层：

Public Class RechargeDAOPublic conn As New SqlConnection("server=.;database=Login;user id=sa;password=li")Public Function SelectUser(ByVal User As RechargeInfo) As BooleanDim eUser As New EntityRecharge.RechargeInfoDim reader As SqlDataReader'Dim intNum1 As IntegerDim sql As String = "SELECT * FROM Recharge WHERE IDcard=@IDcard"Dim cmd As New SqlCommand(sql, conn)cmd.CommandText = sql                     '获取SQL语句的具体内容cmd.CommandType = CommandType.Text         '获取上述SQL语句的具体类型，在此为Selectcmd.Parameters.Add(New SqlParameter("@IDcard", User.IDcard)) '若用成eUser.UserName则会出现参数未传递的错误提示'MsgBox(conn.State)conn.Open()reader = cmd.ExecuteReaderWhile reader.ReadeUser.IDcard = reader.GetInt32(0)End Whileconn.Close()If eUser.IDcard = Nothing ThenReturn FalseElseReturn TrueEnd IfEnd FunctionPublic Function UpdateCash(ByVal User As RechargeInfo) As BooleanDim intNum As IntegerDim eUser As New EntityRecharge.RechargeInfoDim sql As String = "INSERT INTO Recharge (IDcard,AddCash,Cash) VALUES (@IDcard,@AddCash,@Cash)"Dim cmd As New SqlCommand(sql, conn)cmd.CommandText = sqlcmd.CommandType = CommandType.Textcmd.Parameters.Add(New SqlParameter("@IDcard", User.IDcard))cmd.Parameters.Add(New SqlParameter("@AddCash", User.AddCash))cmd.Parameters.Add(New SqlParameter("@Cash", 11 + User.AddCash))conn.Open()                   '打开连接intNum = cmd.ExecuteNonQuery()     '返回 受影响行数conn.Close()        '关闭连接If intNum = 1 ThenReturn TrueElseReturn False       '返回 处理结果End IfEnd FunctionEnd Class

Entity层：

<pre name="code" class="vb">Public Class RechargeInfoDim _idcard As IntegerDim _cash As IntegerDim _addcash As IntegerPublic Property IDcard As Integer          '设置IDcard属性GetReturn _idcardEnd GetSet(value As Integer)_idcard = valueEnd SetEnd PropertyPublic Property AddCash As Integer          '设置AddCash属性GetReturn _addcashEnd GetSet(value As Integer)_addcash = valueEnd SetEnd PropertyPublic Property Cash As Integer             '设置Cash属性GetReturn _cashEnd GetSet(value As Integer)_cash = valueEnd SetEnd Property
End Class

其实吧，这篇和登录那片是差不多的，不一样的地方是，这次在查询的时候，我都用的是Boolean返回值，也就是说，我不需要你查询的数据，我只需要你查询的结果代表的意义，有没有这条数据，有就直接告诉我有，没有就直接告诉我没有，不需要再去比对

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