处理危险字符串

//处理危险字符串
public sealed class CleanString
{
    //定义InputText函数处理用于输入
    public static string InputText(string inputString, int maxLength)
    {
        StringBuilder retVal = new StringBuilder();   //构造临时字符串数组
        if ((inputString != null) && (inputString != string.Empty))
        {
            inputString = inputString.Trim();//清空字符串两段的空白符号
            //设置字符串的长度
            if (inputString.Length > maxLength)
            {
                inputString = inputString.Substring(0,maxLength);
            }
            for (int i = 0; i < inputString.Length; i++)
            {
                switch (inputString[i])   //替换危险字符串
                {
                    case "": retVal.Append("&quot;"); break;
                    case '<': retVal.Append("&lt;"); break;
                    case '>': retVal.Append("&gt;"); break;
                    default: retVal.Append(inputString[i]); break;
                }
            }
            retVal.Replace(""," ");
        }
        return retVal.ToString();
       
    }
}