字符过滤(petshop 中的)

 

using System;
using System.Text;

namespace PetShop.Web.WebComponents
{
    /**//// <summary>
    /// A sample class to clean the input into web pages 
    /// </summary>
    public sealed class CleanString {

        public static string InputText(string inputString, int maxLength) {

            
            StringBuilder retVal = new StringBuilder();

            // check incoming parameters for null or blank string
            if ((inputString != null) && (inputString != String.Empty)) {
                inputString = inputString.Trim();

                //chop the string incase the client-side max length
                //fields are bypassed to prevent buffer over-runs
                if (inputString.Length > maxLength)
                    inputString = inputString.Substring(0, maxLength);

                //convert some harmful symbols incase the regular
                //expression validators are changed
                for (int i = 0; i < inputString.Length; i++) {
                    switch (inputString[i]) {
                        case '"':
                            retVal.Append("&quot;");
                            break;
                        case '<':
                            retVal.Append("&lt;");
                            break;
                        case '>':
                            retVal.Append("&gt;");
                            break;
                        default:
                            retVal.Append(inputString[i]);
                            break;
                    }
                }

                // Replace single quotes with white space
                retVal.Replace("'", " ");
            }

            return retVal.ToString();
            
        }
    }
}