艾伟：Regex.Replace 方法的性能！

2011-08-28 23:55 狼人:-) 阅读(367) 评论(3) 编辑收藏举报

园子里有很多关于去除Html标签的文章。一个常用的经验是使用 Regex.Replace 方法利用正则去替换。这里有一篇使用该方法的文章 C#中如何去除HTML标记。下面我贴出该方法的代码,见代码清单1-1

代码清单1-1 引用 http://www.cnblogs.com/zoupeiyang/archive/2009/06/22/1508039.html

        ///
        /// 去除HTML标记
        ///
        /// 包括HTML的源码
        /// 已经去除后的文字
        public static string ReplaceHtmlTag(string Htmlstring)
        {
            //删除脚本
            Htmlstring = Htmlstring.Replace("\r\n", "");
            Htmlstring = Regex.Replace(Htmlstring, @"", "", RegexOptions.IgnoreCase);
            Htmlstring = Regex.Replace(Htmlstring, @"",@"", "", RegexOptions.IgnoreCase);
            Htmlstring = Regex.Replace(Htmlstring, @"<.*?>", "", RegexOptions.IgnoreCase);
            //删除HTML
            Htmlstring = Regex.Replace(Htmlstring, @"<(.[^>]*)>", "", RegexOptions.IgnoreCase);
            Htmlstring = Regex.Replace(Htmlstring, @"([\r\n])[\s]+", "", RegexOptions.IgnoreCase);
            Htmlstring = Regex.Replace(Htmlstring, @"-->", "", RegexOptions.IgnoreCase);
            Htmlstring = Regex.Replace(Htmlstring, @"",@"",@"<.*?>",
                @"<(.[^>]*)>",@"([\r\n])[\s]+",@"-->",
                @"",@"&(quot|#34);",@"&(amp|#38);",
                @"&(lt|#60);",@"&(gt|#62);",@"&(nbsp|#160);",
                @"&(iexcl|#161);",@"&(cent|#162);",@"&(pound|#163);",
                @"&(copy|#169);",@"&(\d+);"
            };
            string[] replacement = new string[]
            {
                "","","","","","","","\"","&","<",">","","\xa1","\xa2","\xa3","\xa9",""
            };
            #endregion

            if (pattern.Length != replacement.Length)
            {
                throw new Exception("正则表达式数组和替换后的字符数组的长度不一致！");
            }

            int count = 0; //计数器
            foreach (string str in pattern)
            {
                Regex aRegex = new Regex(str);
                aReplaceHtml.AddRegex(aRegex, replacement[count]);
                count += 1;
            }
            return aReplaceHtml;
        }

        ///
        /// 增加一个Regex对象
        ///
        /// Regex 对象
        /// 该对象对应的替换字符串
        private void AddRegex(Regex aRegex, string Replacement)
        {
            _regexs.Add(aRegex);
            _replacement.Add(Replacement);
        }

    }
}

该类的使用如下，见代码清单1-7

代码清单1-7

   public static string ReplaceHtmlTag2(string Htmlstring)
   {
       return ReplaceHtml.Instance.ReplaceHtmlTag(Htmlstring);
   }

写到这里让我们来测试一下，2种方法在性能的差距。经过测试，在重复执行 ReplaceHtmlTag 方法和ReplaceHtmlTag2 方法 10,100,1000 次后，性能相差在 2-15陪左右。具体见图1-1