字符串处理

public sealed class CleanString  {

  #region 数字字符串检查

  private static Regex _isNumber = new Regex("^[0-9]+$");    //检查Request查询字符串的键值，是否是数字，最大长度限制  // return a digit string based on input data  // look first in the QueryString collection,   //then in Form return string.Empty if not found or if non-digit  public static string FetchInputDigit(HttpRequest req, string inputKey, int maxLen)  {   string retVal = string.Empty;   if(inputKey != null && inputKey != string.Empty)   {    retVal = req.QueryString[inputKey];    if(null == retVal)     retVal = req.Form[inputKey];

    if(null != retVal)    {     retVal = CleanString.SqlText(retVal, maxLen);     if(!IsNumber(retVal))      retVal = string.Empty;    }   }

   if(retVal == null)    retVal = string.Empty;

   return retVal;  }

  //是否数字字符串  public static bool IsNumber(string inputData)  {   Match m = _isNumber.Match(inputData);   return m.Success;  }  //是否数字字符串  public static bool IsNumberInt(string inputData)  {   try   {    int.Parse(inputData);   }   catch   {    return false;   }   return true;  }  //是否数字字符串  public static bool IsNumberDecimal(string inputData)  {   try   {    decimal.Parse(inputData);   }   catch   {    return false;   }   return true;  }

    //字符串编码  public static string HtmlEncode(string inputData)  {   return HttpUtility.HtmlEncode(inputData);  }

  public static void SetLabel(Label lbl, string txtInput)  {   lbl.Text = HtmlEncode(txtInput);  }

  public static void SetLabel(Label lbl, object inputObj)  {   SetLabel(lbl, inputObj.ToString());  }

    /// <summary>  /// 检查字符串最大长度，返回指定长度的串  /// </summary>  /// <param name="sqlInput">输入字符串</param>  /// <param name="maxLength">最大长度</param>  /// <returns></returns>     public static string SqlText(string sqlInput, int maxLength)  {      if(sqlInput != null && sqlInput != string.Empty)   {    sqlInput = sqlInput.Trim();           if(sqlInput.Length > maxLength)//按最大长度截取字符串     sqlInput = sqlInput.Substring(0, maxLength);   }

   return sqlInput;  }

  #endregion

  //字符串清理  public static string InputText(string inputString, int maxLength)   {      StringBuilder retVal = new StringBuilder();

   // 检查是否为空   if ((inputString != null) && (inputString != String.Empty))    {    inputString = inputString.Trim();

        //检查长度    if (inputString.Length > maxLength)     inputString = inputString.Substring(0, maxLength);

        //替换危险字符    for (int i = 0; i < inputString.Length; i++)     {     switch (inputString[i])      {      case '"':       retVal.Append(""");       break;      case '<':       retVal.Append("<");       break;      case '>':       retVal.Append(">");       break;      default:       retVal.Append(inputString[i]);       break;     }    }

    // 替换单引号    retVal.Replace("'", " ");   }

   return retVal.ToString();     } }