用了我一下午的时间终于写完并整理好了利用.net来发送即时消息的材料（当然了，还有上午的数据库设计：）
   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（这是和我做的学友录连在一起的），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。
  下面的代码家在校友录中的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("<script language=JavaScript>window.open('info.aspx','','height=330,width=560,status=no,location=no,toolbar=no,directories=no,menubar=no')</script>")
   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("<script language=javascript>alert('发送成功！')</script>")
   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
  
  
  页面部分：
  <%@ Page Language="vb" AutoEventWireup="false" Codebehind="info.aspx.vb" Inherits="_99re1.info"%>
  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
  <HTML>
   <HEAD>
   <title></title>
   <meta content="Microsoft Visual Studio.NET 7.0" name="GENERATOR">
   <meta content="Visual Basic 7.0" name="CODE_LANGUAGE">
   <meta content="JavaScript" name="vs_defaultClientScript">
   <meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema">
   </HEAD>
   <body background="image/bg.gif" MS_POSITIONING="GridLayout">
   <form id="Form1" method="post" runat="server">
   <FONT face="宋体">
   <asp:image id="Image3" style="Z-INDEX: 111; LEFT: 141px; POSITION: absolute; TOP: 312px" runat="server" Width="221px" Height="98px" ImageUrl="image/99re1-1.gif"></asp:image>
   <asp:textbox id="TextBox1" style="Z-INDEX: 101; LEFT: 73px; POSITION: absolute; TOP: 123px" runat="server" BorderColor="Navy" BorderWidth="1px"></asp:textbox>
   <asp:label id="Label1" style="Z-INDEX: 102; LEFT: 26px; POSITION: absolute; TOP: 127px" runat="server" Width="42px" Height="18px" Font-Size="X-Small" ForeColor="Navy" Font-Bold="True">发往：</asp:label>
   <asp:label id="Label2" style="Z-INDEX: 103; LEFT: 26px; POSITION: absolute; TOP: 156px" runat="server" Font-Size="X-Small" ForeColor="Navy" Font-Bold="True">内容：</asp:label>
   <asp:textbox id="TextBox2" style="Z-INDEX: 104; LEFT: 73px; POSITION: absolute; TOP: 154px" runat="server" TextMode="MultiLine" Width="449px" Height="74px" BorderColor="Navy" BorderWidth="1px" MaxLength="200"></asp:textbox>
   <asp:button id="Button1" style="Z-INDEX: 105; LEFT: 357px; POSITION: absolute; TOP: 252px" runat="server" Width="50px" Height="20px" Text="发送" BorderColor="Navy" BorderWidth="1px" BackColor="#FFE0C0"></asp:button>
   <asp:button id="Button2" style="Z-INDEX: 106; LEFT: 176px; POSITION: absolute; TOP: 253px" runat="server" Width="87px" Height="20px" Text="继续发送…" BorderColor="Navy" BorderWidth="1px" BackColor="#FFE0C0"></asp:button>
   <asp:label id="Label3" style="Z-INDEX: 107; LEFT: 75px; POSITION: absolute; TOP: 10px" runat="server" Width="135px" Height="6px" Font-Size="Small">Label</asp:label>
   <asp:label id="Label4" style="Z-INDEX: 108; LEFT: 300px; POSITION: absolute; TOP: 9px" runat="server" Width="219px" Height="13px" Font-Size="Small">Label</asp:label>
   <asp:label id="Label5" style="Z-INDEX: 109; LEFT: 73px; POSITION: absolute; TOP: 40px" runat="server" Width="447px" Height="71px" Font-Size="X-Small" BorderColor="SlateGray" BorderWidth="1px">Label</asp:label>
   <asp:label id="Label6" style="Z-INDEX: 110; LEFT: 26px; POSITION: absolute; TOP: 12px" runat="server" Font-Size="X-Small" ForeColor="Red" Font-Bold="True">来自：</asp:label>
   <asp:TextBox id="TextBox3" style="Z-INDEX: 112; LEFT: 247px; POSITION: absolute; TOP: 122px" runat="server" Visible="False"></asp:TextBox>
   <asp:Label id="Label8" style="Z-INDEX: 113; LEFT: 116px; POSITION: absolute; TOP: 55px" runat="server" Height="33px" Width="327px" Font-Bold="True" ForeColor="Navy" Font-Size="Large" Font-Names="方正姚体" Font-Underline="True">直接写入内容点击发送即可！</asp:Label>
   <asp:Label id="Label7" style="Z-INDEX: 114; LEFT: 225px; POSITION: absolute; TOP: 12px" runat="server" Height="15px" Width="71px" Font-Bold="True" ForeColor="Red" Font-Size="X-Small">发信日期：</asp:Label>
   <asp:Label id="Label9" style="Z-INDEX: 115; LEFT: 25px; POSITION: absolute; TOP: 41px" runat="server" Font-Bold="True" ForeColor="Red" Font-Size="X-Small">内容：</asp:Label>
   </FONT>
   </form>
   </body>
  </HTML>
  以上代码在bata2环境下调试成功.
  
  特别感谢：cheery_ke提供思路！
  朋友一生一起走，多一个朋友就多一分收获！