C#編寫檢測QQ狀態是否在線實例代碼

C#查詢QQ狀態是否在線實例代碼如下：
private void button3_Click(object sender, System.EventArgs e)
{
        if(textBox3.Text=="")
        {
                MessageBox.Show("必須填寫當前的查詢的QQ號碼!","錯誤提示!");
                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 "不在線","QQ狀態提示!");
                        break;
                        case "GIF89aJ":MessageBox.Show(strQQ "在線","QQ狀態提示!");
                        break;          
                }
        }
}