asp.net 常用字符串过滤方法

using System;
using System.Text;
using System.Text.RegularExpressions;

namespace bjmti
{
/// <summary>
/// include 的摘要说明。
/// </summary>
public class include
{
public include()
{
   //
   // TODO: 在此处添加构造函数逻辑
   //
}

#region 字符串截取函数
/// <summary>
/// 字符串截取函数
/// </summary>
/// <param name="inputString">要截取的字符串</param>
/// <param name="len">要截取的长度</param>
/// <returns>string</returns>
///
public static string CutString(string inputString,int len)
{


   ASCIIEncoding ascii = new ASCIIEncoding();
   int tempLen=0;
   string tempString="";
   byte[] s = ascii.GetBytes(inputString);
   for(int i=0;i<s.Length;i++)
   {
    if((int)s[i]==63)
    {
     tempLen+=2;
    }
    else
    {
     tempLen+=1;
    }

    try
    {
     tempString+=inputString.Substring(i,1);
    }
    catch
    {
     break;
    }

    if(tempLen>len)
     break;
   }
//   //如果截过则加上半个省略号
//   byte[] mybyte=System.Text.Encoding.Default.GetBytes(inputString);
//   if(mybyte.Length>len)
//    tempString+="…";

return tempString;
}
#endregion

#region 生成由日期组成的唯一的文件名
/// <summary>
/// 生成由日期组成的唯一的文件名
/// </summary>
/// <returns>string</returns>
///
public static string makeFileName()
{
   string newFileName;
   string dateName = System.DateTime.Now.ToString("yyyyMMddhhmmss");
   System.Random srd = new Random();
   int srdName = srd.Next(1000);
   newFileName = dateName+srdName.ToString();
   return newFileName;
}
#endregion

#region 过滤特殊字符
/// <summary>
/// 过滤特殊字符
/// </summary>
/// <param name="inputStr">字符串</param>
/// <returns>string</returns>
public static string cutBadStr(string inputStr)
{
   inputStr = inputStr.ToLower().Replace(",","");
   inputStr = inputStr.ToLower().Replace("<","<");
   inputStr = inputStr.ToLower().Replace(">",">");
   inputStr = inputStr.ToLower().Replace("%","");
   inputStr = inputStr.ToLower().Replace(".","");
   inputStr = inputStr.ToLower().Replace(":","");
   inputStr = inputStr.ToLower().Replace("#","");
   inputStr = inputStr.ToLower().Replace("&","");
   inputStr = inputStr.ToLower().Replace("$","");
   inputStr = inputStr.ToLower().Replace("^","");
   inputStr = inputStr.ToLower().Replace("*","");
   inputStr = inputStr.ToLower().Replace("`","");
   inputStr = inputStr.ToLower().Replace(" ","");
   inputStr = inputStr.ToLower().Replace("~","");
   inputStr = inputStr.ToLower().Replace("or","");
   inputStr = inputStr.ToLower().Replace("and","");
   return inputStr;

}
#endregion

#region 过滤html标记
/// <summary>
/// 过滤html标记
/// </summary>
/// <param name="HTMLStr">要过滤的字符串</param>
/// <returns>string</returns>
///

public static string CutHTML(string strHtml)
{
   string   []   aryReg   ={
          @"<script[^>]*?>.*?</script>",

          @"<(\/\s*)?!?((\w+:)?\w+)(\w+(\s*=?\s*(([""'])(http://www.cnblogs.com/lds85930/admin/file://[%22%22'tbnr]%7c[%5e/7])*?\7|\w+)|.{0})|\s)*?(\/\s*)?>",
          @"([\r\n])[\s]+",
          @"&(quot|#34);",
          @"&(amp|#38);",
          @"&(lt|#60);",
          @"&(gt|#62);",
          @"&(nbsp|#160);",
          @"&(iexcl|#161);",
          @"&(cent|#162);",
          @"&(pound|#163);",
          @"&(copy|#169);",
          @"&#(\d+);",
          @"-->",
          @"<!--.*\n"
         };

   string   []   aryRep   =   {
             "",
             "",
             "",
             "\"",
             "&",
             "<",
             ">",
             "   ",
             "\xa1",//chr(161),
             "\xa2",//chr(162),
             "\xa3",//chr(163),
             "\xa9",//chr(169),
             "",
             "\r\n",
             ""
            };

   string   newReg   =aryReg[0];
   string   strOutput=strHtml;
   for(int   i   =   0;i<aryReg.Length;i++)
   {
    Regex   regex   =   new   Regex(aryReg[i],RegexOptions.IgnoreCase);
    strOutput   =   regex.Replace(strOutput,aryRep[i]);
   }
   strOutput.Replace("<","");
   strOutput.Replace(">","");
   strOutput.Replace("\r\n","");
   return   strOutput;
}
#endregion

#region 标题固定长度


/// <summary>
/// <table style="font-size:12px">
/// <tr><td><b>功能描述</b>：填充或截断原始字符串为指定长度 </td></tr>
/// <tr><td><b>创建人</b>： </td></tr>
/// <tr><td><b>创建时间</b>：</td></tr>
/// </table>
/// </summary>
/// <param name="strOriginal">原始字符串</param>
/// <param name="maxTrueLength">字符串的字节长度</param>
/// <param name="chrPad">填充字符</param>
/// <param name="blnCutTail">字符串的字节长度超过maxTrueLength时截断多余字符</param>
/// <returns>填充或截断后的字符串</returns>
static public string PadRightTrueLen(string strOriginal,int maxTrueLength,char chrPad,bool blnCutTail)
{
   string strNew = strOriginal;

   if (strOriginal==null || maxTrueLength<=0)
   {
    strNew = "";
    return strNew;
   }

   int trueLen = TrueLength(strOriginal);
   if (trueLen>maxTrueLength)//超过maxTrueLength
   {
    if (blnCutTail)//截断
    {
     for(int i=strOriginal.Length-1; i>0; i--)
     {
      strNew = strNew.Substring(0,i);
      if (TrueLength(strNew) == maxTrueLength)
       break;
      else if (TrueLength(strNew) < maxTrueLength)
      {
       strNew += chrPad.ToString();
       break;
      }
     }
    }
   }
   else//填充
   {
    for(int i=0;i<maxTrueLength-trueLen;i++)
    {
     strNew += chrPad.ToString();
    }
   }

return strNew;
}

//主方法
public static string CutStringTitle(string inputString,int i)
{
         return PadRightTrueLen(inputString,i,' ',true);
}

/// <summary>
/// <table style="font-size:12px">
/// <tr><td><b>功能描述</b>：字符串的字节长度 </td></tr>
/// <tr><td><b>创建人</b>： </td></tr>
/// <tr><td><b>创建时间</b>：</td></tr>
/// </table>
/// </summary>
/// <param name="str">字符串</param>
/// <returns>字符串的字节长度</returns>
static public int TrueLength(string str)
{
   int lenTotal = 0;
   int n = str.Length;
   string strWord = "";
   int asc;
   for(int i=0;i<n;i++)
   {
    strWord = str.Substring(i,1);
    asc = Convert.ToChar(strWord);
    if ( asc < 0 || asc > 127 )
     lenTotal = lenTotal + 2;
    else
     lenTotal = lenTotal + 1;
   }

return lenTotal;
}
#endregion

#region 关闭当前窗口(静态)
/// <summary>
/// (Descript) 关闭当前窗口(静态)
///   (Author) warfu
///     (Date) 2007-08-28
/// </summary>
public static void CloseWindow()
{
   System.Web.HttpContext.Current.Response.Write("<SCRIPT LANGUAGE=JAVASCRIPT>window.close()</SCRIPT>");
}
#endregion

#region 打开没有Toolbar的新窗口(静态)

/// <summary>
/// 返回js脚本——window.open('','')
/// </summary>
/// <param name="url">网址</param>
/// <param name="name">目标</param>
/// <returns></returns>
public static string openWeb(string url,string name)
{
//输出提示信息
return "<script language=javascript>window.open('"+ url +"','"+ name +"')</script>";
}

/// <summary>
/// 打开没有Toolbar的新窗口(静态)
/// </summary>
/// <param name="str_Url">页面路径</param>
/// <param name="int_Height">窗口高度</param>
/// <param name="int_Width">窗口宽度</param>
/// <param name="str_WebName">窗口名称</param>
public static void OpenWindow(string str_Url,int int_Height,int int_Width,string str_WebName)
{
   //构造JAVASCRIPT
   string str_JavaScript = @"<Script language='JavaScript'>
   window.open('"mailto:+str_Url+@%22','%22+str_WebName+@%22','height="+ int_Height mailto:+@%22','width="+ int_Width mailto:+@%22','top=0,left=0,location=no,menubar=no,resizable=yes,scrollbars=yes,status=yes,titlebar=yes,toolbar=no,directories=no');
   </Script>";

System.Web.HttpContext.Current.Response.Write(str_JavaScript);

}
#endregion

}
}

我们知道，在C#（.Net）内部所使用Unicode来存储字符串，这样在处理字符串的时候偶尔会发生一些不爽的事情。比如，如果字符串中有中文字符，而我们想取得固定长度字符串就颇为麻烦，下面提供了一个解决方案。在这个方案中，我们实现了这么几个功能：

取得给出字符串靠左边的子串，子串的大小为为指定长度；
如果给出的字符串长度大于给出的长度，则在子串的末端加上“..”。
避免出现半个汉字的情况。
源码如下：

private string getLeftSubString(string content, int length)
{
   Encoding encoding = Encoding.GetEncoding("gb2312");
   StringBuilder sb = new StringBuilder();
   int totalLength = 0;
   foreach (char contentChar in content)
   {
      int size = encoding.GetByteCount(new char[] { contentChar });
      if (totalLength + size > length -2)
      {
         sb.Append("..");
         break;
      }
      sb.Append(contentChar);
      totalLength += size;
   }
   return sb.ToString();
}