过滤非法字符（脏字）的类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Web;
using System.Collections;

namespace ******.WebHelper
{
    public class FilterText
    {
        string FilePath = string.Empty;
        public FilterText()
        {
            FilePath = HttpContext.Current.Server.MapPath("~/Config/ValidDict.txt");//脏字文件的路径
        }
        /// <summary>
        /// 读文件的内容
        /// </summary>
        /// <param name="url">物理路径</param>
        /// <returns></returns>
        public string ReadFilterText()
        {
            FileStream fsReadDefaultTemplate = new FileStream(FilePath, FileMode.Open, FileAccess.Read);
            StreamReader srReadDefaultTemplate = new StreamReader(fsReadDefaultTemplate, System.Text.Encoding.UTF8);
            string content = srReadDefaultTemplate.ReadToEnd();
            fsReadDefaultTemplate.Close();
            srReadDefaultTemplate.Close();
            return content;
        }

        /// <summary>
        /// 写非法关键字到文件
        /// </summary>
        /// <param name="url">物理路径</param>
        /// <param name="content">内容</param>
        /// <returns></returns>
        public void WriteFilterText(string content)
        {
            FileStream fs = new FileStream(FilePath, FileMode.Create, FileAccess.Write);
            StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.UTF8);            
            sw.Write(content);
            sw.Close();
            fs.Close();
        }
        /// <summary>
        /// 过滤非法字符,替换为*号
        /// </summary>
        /// <param name="TempStr">需要过滤的字符串</param>
        /// <returns></returns>
        public string FilterInfo(string TempStr)
        {
            if (File.Exists(FilePath))
            {
                StreamReader objReader = new StreamReader(FilePath, System.Text.Encoding.UTF8);
                string sLine = "";
                ArrayList arrText = new ArrayList();
                while (sLine != null)
                {
                    sLine = objReader.ReadLine();
                    if (sLine != null)
                        arrText.Add(sLine);
                }
                objReader.Close();
                foreach (string sOutput in arrText)
                {
                    string[] strArr = sOutput.Split(new char[] { (char)10, (char)13 }, StringSplitOptions.RemoveEmptyEntries);

                    for (int i = 0; i < strArr.Length; i++)
                    {
                        string temp = "";
                        for (int j = 0; j < strArr[i].Length; j++)
                        { temp += "*"; }
                        TempStr = TempStr.Replace(strArr[i], temp);
                    }
                }
            }
            return TempStr;
        }
    }
}