c#查询QQ状态是否在线查询代码

private void button3_Click(object sender, System.EventArgs e)
  {
   if(textBox3.Text=="")
   {
    MessageBox.Show("必须填写当前的查询的QQ号码!","错误提示!");
    textBox3.Focus();
    return;    
   }
   else
   {
    string strQQ=textBox3.Text.Trim();
    string strSearchQQ="http://wpa.qq.com/pa?p=1:"+strQQ+":3";
    string strQQStatus=GetWebContent(strSearchQQ).Substring(0,7);
    switch(strQQStatus)
    {
     case "GIF89aK":MessageBox.Show(strQQ+"不在线","QQ状态提示!");
      break;
     case "GIF89aJ":MessageBox.Show(strQQ+"在线","QQ状态提示!");
      break;          
    } 
   }
  }