3。解析要点：
            一行一行获取再解析
            跳过以#打头的注释行
            过滤掉空格后，首字符在A~z之间的行就包含了Oracle服务名
            截取该行第一个“＝”号左边的字符串，trim处理后就是Oracle服务名了
        */
        public static string[] GetOracleTnsNames()
        {
            try
            {
                // 查询注册表，获取oracle服务文件路径
                RegistryKey key = Registry.LocalMachine.OpenSubKey("SOFTWARE").OpenSubKey("ORACLE");
                string home = (string)key.GetValue("ORACLE_HOME");
                string file = home + @"\network\ADMIN\tnsnames.ora";

                // 解析文件
                string line;
                ArrayList arr = new ArrayList();
                StreamReader sr = new StreamReader(file);
                while ((line = sr.ReadLine()) != null)
                {
                    line = line.Trim();
                    if (line != "")
                    {
                        char c = line[0];
                        if ( c>= 'A' && c<='z')
                            arr.Add(line.Substring(0, line.IndexOf(' ')));
                    }
                }
                sr.Close();

                // 返回字符串数组
                return (string[])arr.ToArray(typeof(string));
            }
            catch (Exception ex)
            {
                return null;
            }
        }