Introduction
实现用户登录功能，UI使用WinForm提供LoginForm,然后建一个User表保存用户信息（UserName, PassWrd, UserActive, Comment），使用Linq对User表进行查询。
plainText = CryptographyUtils.Decrypt(CryptographyUtils.CreateSymmAlgoRC2(),cipherText, "JK_huangJK_huang", 128CryptographyUtils.CreateSymmAlgoRC2(),cipherText, "JK_huangJK_huang", 128);
Backgroud
使用Visual studio2008,sql server 2005开发
The Definition of User Table
SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[t_UserInfo]( [UserName] [nvarchar](20) NOT NULL, [PassWrd] [nvarchar](20) NOT NULL, [UserActive] [bit] NOT NULL, [Comment] [nvarchar](50) NULL, CONSTRAINT [PK_t_UserInfo] PRIMARY KEY CLUSTERED ( [UserName] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY]
Validing the user and Passing Data to Database
上传数据方法，当CheckReg.Checked = True是创建新用户，False时检验当前用户是否有效
Private Sub OK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK.Click Dim loginDS As New TestInfoDataSet.t_UserInfoDataTable Dim loginDA As New TestInfoDataSetTableAdapters.t_UserInfoTableAdapter If CheckReg.Checked = True Then Try loginDA.Insert(comUser.Text.ToString(), txtPW.Text.ToString(), True, "") Catch ex As Exception MessageBox.Show("The UserName already exist", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information) comUser.Focus() comUser.Text = "" Finally Me.ClearForm() End Try Else Try loginDA.FillByUserData(loginDS, comUser.ToString(), txtPW.ToString()) Check_Details() Catch ex As Exception MsgBox("Invalid User Name", MsgBoxStyle.Critical, "Error") End Try End If End Sub
使用Linq查询用户是否存在User表中
Private Sub Check_Details() Dim PWord As String = Me.txtPW.Text.ToString.Trim Dim CheckDA As New TestInfoDataSetTableAdapters.t_UserInfoTableAdapter Dim query = From check In CheckDA.GetData _ Select check.UserName, check.PassWrd, check.UserActive _ Where UserName = UName AndAlso PassWrd = PWord _ AndAlso UserActive = True If query.Count() = 1 Then MessageBox.Show("confirmed", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information) Me.ClearForm() Else MessageBox.Show("Password Is Incorrect or no longer Valid", "Incorrect Password", MessageBoxButtons.OK, MessageBoxIcon.Information) txtPW.Focus() txtPW.Text = "" End If End Sub
Data Valide
进行输入操作时是全角输入就要转换为半角输入，这里使用两种方法进行全角到半角的转换
1.处理输入后的数据2.只输入半角字符
Private Function ToDBC(ByVal tmpStr As String) As String Dim i As Integer = 0 Dim c() As Char = tmpStr.ToCharArray() Dim length As Integer = c.Length - 1 For i = 0 To length If c(i) = " " Then c(i) = CChar(" ") ElseIf AscW(c(i)) > 65280 And AscW(c(i)) < 65375 Then c(i) = ChrW(AscW(c(i)) - 65248) End If Next Return CStr(c) End Function End Class
2.关闭输入法
Me.comUser.ImeMode = Forms.ImeMode.Close ‘直接关闭全角输入
http://files.cnblogs.com/rush/登录检验程序.rar
The experience of project
Visual Basic 不会在 Char 类型和数值类型之间直接转换。可以使用 Asc 或 AscW 函数将 Char 值转换为表示其码位的 Integer。可以使用 Chr 或 ChrW 函数将 Integer 值转换为具有该码位的 Char。
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