.net中即时消息发送的实现

　     数据库设计：info表：id fromstu_id tostu_id content term

   其中id是主键，fromstu_id是发送信息的用户的学号，tostu_id是接受信息的用户的学号，content是消息的内容，term是判断是否为新消息。

   下面的代码加在校友录中的if not ispostback中

'/////////////////////判断是否有新留言，将自动弹出页面。这里还要将页面的刷新时间设置一下，以便可以循环的读取信息。

Dim mysql As String = "select * from info where tostu_id=@myid and term=1"

Dim comm As SqlCommand = New SqlCommand(mysql, conn)

comm.Parameters.Add(New SqlParameter("@myid", SqlDbType.Int, 4))

comm.Parameters("@myid").Value = Session("stu_id")

Dim dr As SqlDataReader

conn.Open()

dr = comm.ExecuteReader

If dr.Read Then

Response.Write(" ")

End If

dr.Close()

comm.Cancel()

下面的代码是用来发送即时消息的页面，其中里面分了两个部分，一个是用来回复的，一个是用来专门发送的，两个的页面稍有区别，仔细看一下就会明白的。

下面是所有的代码：codebehind部分

Public Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

If Not IsPostBack Then

Dim tostu_id As String = Request.QueryString("tostu_id")

If tostu_id = "" Then

'//////////////////当回复留言时

Dim sql As String = "select a.*,b.nick from info a,pwd b where a.fromstu_id=b.stu_id and a.tostu_id='" & Session("stu_id") & "' and a.term=1"

Dim comm As SqlCommand = New SqlCommand(sql, conn)

Dim dr As SqlDataReader

conn.Open()

dr = comm.ExecuteReader

While dr.Read

Label3.Text = dr.Item("nick")

Label4.Text = dr.Item("tim")

Label5.Text = dr.Item("content")

TextBox1.Text = dr.Item("nick")

TextBox3.Text = dr.Item("fromstu_id")

TextBox1.Enabled = False

Label8.Visible = False

End While

dr.Close()

comm.Cancel()

'//////////////////////更新留言使留言属性为已阅读过

Dim sql_1 As String = "update info set term=0 where tostu_id='" & Session("stu_id") & "' and term=1 and tim='" & Label4.Text & "'"

comm = New SqlCommand(sql_1, conn)

comm.ExecuteNonQuery()

Else

'////////////////////当发送留言时

Dim mysql As String = "select nick from pwd where stu_id='" & tostu_id & "'"

Dim comm As SqlCommand = New SqlCommand(mysql, conn)

Dim dr As SqlDataReader

conn.Open()

dr = comm.ExecuteReader

While dr.Read

TextBox1.Text = dr.item("nick")

End While

TextBox1.Enabled = False

Label3.Text = ""

Label4.Text = ""

Label5.Visible = False

Label8.Visible = True

Label6.Visible = False

Label7.Visible = False

Label9.Visible = False

dr.close()

End If

End If

End Sub

'/////////////////书写提交消息事件

Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim tostu_id As String = Request.QueryString("tostu_id")

If tostu_id = "" Then

'/////////////////////////当回复留言时

conn.Open()

Dim sql As String = "insert into info(fromstu_id,tostu_id,content,term,tim) values(@fromstu_id,@tostu_id,@content,@term,@tim)"

Dim comm As SqlCommand = New SqlCommand(sql, conn)

comm.Parameters.Add(New SqlParameter("@fromstu_id", SqlDbType.Int, 4))

comm.Parameters("@fromstu_id").Value = Session("stu_id")

comm.Parameters.Add(New SqlParameter("@tostu_id", SqlDbType.Int, 4))

comm.Parameters("@tostu_id").Value = TextBox3.Text

comm.Parameters.Add(New SqlParameter("@content", SqlDbType.VarChar, 200))

comm.Parameters("@content").Value = TextBox2.Text

comm.Parameters.Add(New SqlParameter("@term", SqlDbType.Int, 4))

comm.Parameters("@term").Value = "1"

comm.Parameters.Add(New SqlParameter("@tim", SqlDbType.Char, 20))

comm.Parameters("@tim").Value = Date.Now

comm.ExecuteNonQuery()

TextBox2.Text = ""

Else

'/////////////////////////当发送留言时

conn.Open()

Dim sql As String = "insert into info(fromstu_id,tostu_id,content,term,tim) values(@fromstu_id,@tostu_id,@content,@term,@tim)"

Dim comm As SqlCommand = New SqlCommand(sql, conn)

comm.Parameters.Add(New SqlParameter("@fromstu_id", SqlDbType.Int, 4))

comm.Parameters("@fromstu_id").Value = Session("stu_id")

comm.Parameters.Add(New SqlParameter("@tostu_id", SqlDbType.Int, 4))

comm.Parameters("@tostu_id").Value = tostu_id

comm.Parameters.Add(New SqlParameter("@content", SqlDbType.VarChar, 200))

comm.Parameters("@content").Value = TextBox2.Text

comm.Parameters.Add(New SqlParameter("@term", SqlDbType.Int, 4))

comm.Parameters("@term").Value = "1"

comm.Parameters.Add(New SqlParameter("@tim", SqlDbType.Char, 20))

comm.Parameters("@tim").Value = Date.Now

comm.ExecuteNonQuery()

TextBox2.Text = ""

End If

Response.Write(" ")

End Sub

'////////////////////返回继续发送

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

Response.Redirect("boaman.aspx")

End Sub

End Class