常用的一些字符串处理函数

 

  1using System;
  2using System.Collections.Generic;
  3using System.Text;
  4using System.Web.Security;
  5using System.Security.Cryptography;
  6using System.Text.RegularExpressions;
  7
  8public class StringHelper
  9    {
 10        /**//// <summary>
 11        ///将字符串格式化为HTML
 12        /// </summary>
 13        /// <param name="normalStr">所要格式化的字符串</param>
 14        /// <returns>返回格式化后的HTML代码</returns>
 15        public static string FormatToHtml(string normalStr)
 16        {
 17            normalStr = System.Web.HttpContext.Current.Server.UrlDecode(normalStr);
 18            normalStr = System.Web.HttpContext.Current.Server.HtmlEncode(normalStr);
 19
 20            StringBuilder html = new StringBuilder(normalStr);
 21
 22            html.Replace(" ", "&nbsp;");
 23            html.Replace("\r\n", "<br />");
 24
 25            return html.ToString();
 26        }
 27
 28        /**//// <summary>
 29        /// 将HTML转为普通文本格式
 30        /// </summary>
 31        /// <param name="htmlStr">所要转换的HTML字符串</param>
 32        /// <returns>返回普通文本</returns>
 33        public static string RestoreFromHtml(string htmlStr)
 34        {
 35            htmlStr = System.Web.HttpContext.Current.Server.HtmlDecode(htmlStr);
 36
 37            StringBuilder normalStr = new StringBuilder(htmlStr);
 38
 39            normalStr.Replace("<br />", "\r\n");
 40
 41            normalStr.Replace("&quot;", "\"");
 42            normalStr.Replace("&lt;", "<");
 43            normalStr.Replace("&gt;", ">");
 44            normalStr.Replace("&nbsp;", " ");
 45            normalStr.Replace("&amp;", "&");
 46
 47            return normalStr.ToString();
 48        }
 49
 50        /**//// <summary>
 51        /// 
 52        /// </summary>
 53        /// <param name="str"></param>
 54        /// <param name="length"></param>
 55        /// <returns></returns>
 56        public static string CutString(string str, int length)
 57        {
 58            if (str != null && str.Length > length)
 59            {
 60                return string.Format("{0}.", str.Substring(0, length));
 61            }
 62            else
 63            {
 64                return str;
 65            }
 66        }
 67
 68        /**//// <summary>
 69        /// 
 70        /// </summary>
 71        /// <param name="withOut"></param>
 72        /// <returns></returns>
 73        public static string GetCurrentQueryString(string withOut)
 74        {
 75            string _getkeys = "";
 76            string _result = "";
 77
 78            if (System.Web.HttpContext.Current.Request.QueryString != null)
 79            {
 80                for (int i = 0; i < System.Web.HttpContext.Current.Request.QueryString.Count; i++)
 81                {
 82                    _getkeys = System.Web.HttpContext.Current.Request.QueryString.Keys[i];
 83                    if (_getkeys != withOut)
 84                    {
 85                        _result = string.Format("{0}&{1}={2}", _result, _getkeys, System.Web.HttpContext.Current.Request.QueryString[_getkeys]);
 86                    }
 87                }
 88            }
 89
 90            return _result;
 91        }
 92
 93        /**//// <summary>
 94        /// 对字符串进行加密（不可逆）
 95        /// 0 is SHA1,1 is MD5
 96        /// </summary>
 97        /// <param name="Password">要加密的字符串</param>
 98        /// <param name="Format">加密方式,0 is SHA1,1 is MD5</param>
 99        /// <returns></returns>
100        public static string HashEncrypt(string Password, int Format)
101        {
102            string strResult = "";
103            switch (Format)
104            {
105                case 0:
106                    strResult = FormsAuthentication.HashPasswordForStoringInConfigFile(Password, "SHA1");
107                    break;
108                case 1:
109                    strResult = FormsAuthentication.HashPasswordForStoringInConfigFile(Password, "MD5");
110                    break;
111                default:
112                    strResult = Password;
113                    break;
114            }
115
116            return strResult;
117        }
118
119        /**//// <summary>
120        /// 使用SHA1Managed类产生长度为160位哈希值。不需要提供密钥。
121        /// </summary>
122        /// <returns></returns>
123        public string SHA1ManagedHasher(string hashText)
124        {
125            byte[] SHA1Data = System.Text.Encoding.UTF8.GetBytes(hashText);
126
127            SHA1Managed Sha1 = new SHA1Managed();
128
129            byte[] Result = Sha1.ComputeHash(SHA1Data);
130
131            return Convert.ToBase64String(Result); //返回长度为28字节的字符串
132        }
133
134        防SQL注入式攻击代码#region 防SQL注入式攻击代码
135
136        /**//// <summary>
137        /// 处理用户提交的请求
138        /// </summary>
139        public static void StartProcessRequest()
140        {
141            try
142            {
143                string getkeys = "";
144
145                Regex _regex = new Regex("\\b(and|exec|insert|select|delete|update|count|chr|mid|master|truncate|char|declare)\\b|\\*");
146
147                if (System.Web.HttpContext.Current.Request.QueryString != null)
148                {
149                    for (int i = 0; i < System.Web.HttpContext.Current.Request.QueryString.Count; i++)
150                    {
151                        getkeys = System.Web.HttpContext.Current.Request.QueryString.Keys[i];
152                        if (_regex.IsMatch(System.Web.HttpContext.Current.Request.QueryString[getkeys]))
153                        {
154                            System.Web.HttpContext.Current.Response.Redirect("~/Default.aspx");
155                            System.Web.HttpContext.Current.Response.End();
156                        }
157                    }
158                }
159                if (System.Web.HttpContext.Current.Request.Form != null)
160                {
161                    for (int i = 0; i < System.Web.HttpContext.Current.Request.Form.Count; i++)
162                    {
163                        getkeys = System.Web.HttpContext.Current.Request.Form.Keys[i];
164                        if (_regex.IsMatch(System.Web.HttpContext.Current.Request.Form[getkeys]))
165                        {
166                            System.Web.HttpContext.Current.Response.Redirect("~/Default.aspx");
167                            System.Web.HttpContext.Current.Response.End();
168                        }
169                    }
170                }
171            }
172            catch
173            {
174                // 错误处理: 处理用户提交信息!
175            }
176        }
177
178        /**//// <summary>
179        /// 分析用户请求是否正常
180        /// </summary>
181        /// <param name="Str">传入用户提交数据</param>
182        /// <returns>返回是否含有SQL注入式攻击代码</returns>
183        private static bool ProcessSqlStr(string Str)
184        {
185            bool ReturnValue = true;
186            try
187            {
188                if (Str != "")
189                {
190                    //string SqlStr = "and |exec |insert |select |delete |update |count | * |chr |mid |master |truncate |char |declare ";
191                    string[] anySqlStr = { "and ", "exec ", "insert ", "select ", "delete ", "update ", "count ", " * ", "chr ", "mid ", "master ", "truncate ", "char ", "declare " };
192                    foreach (string ss in anySqlStr)
193                    {
194                        if (Str.IndexOf(ss) >= 0)
195                        {
196                            ReturnValue = false;
197                        }
198                    }
199                }
200            }
201            catch
202            {
203                ReturnValue = false;
204            }
205            return ReturnValue;
206        }
207
208        #endregion
209}