对关键字过滤 - 风里的叶子

对关键字过滤
  1 /// <summary>
  2 /// 过滤类
  3 /// </summary>
  4     class Filter
  5     {
  6         private string replaceChat = "*";
  7         /// <summary>
  8 /// 替代过滤后的字符
  9 /// </summary>
 10         public string ReplaceChat
 11         {
 12             get { return replaceChat; }
 13             set { replaceChat = value; }
 14         }
 15 
 16         private string[] keys;
 17         /// <summary>
 18 /// 要过滤的关键字
 19 /// </summary>
 20         public string[] Keys
 21         {
 22             get { return keys; }
 23             set 
 24             { 
 25                 keys = value;
 26                 if (value != null && value.Length != 0)
 27                 {
 28                     foreach(string str in value)
 29                     {
 30                         string key = str.ToUpper();
 31                         Dictionary<char, object> dictionary = this.KeysDictionary;
 32                         foreach (char c in key)
 33                         {
 34                             if (!dictionary.ContainsKey(c))
 35                             {
 36                                 dictionary.Add(c, new Dictionary<char, object>());
 37                             }
 38                             dictionary = dictionary[c] as Dictionary<char, object>;
 39                         }
 40                         dictionary.Add('\0', 0);
 41                     }
 42                 }
 43             }
 44         }
 45         /// <summary>
 46 /// 存放关键字的Dictionary字典
 47 /// </summary>
 48         private Dictionary<char, object> keysDictionary = new Dictionary<char, object>();
 49 
 50         public Dictionary<char, object> KeysDictionary
 51         {
 52             get { return keysDictionary; }
 53             set { keysDictionary = value; }
 54         }
 55 
 56         public Filter()
 57         { }
 58         /// <summary>
 59 /// 构造器
 60 /// </summary>
 61 /// <param name="keys">过滤的关键字</param>
 62         public Filter(string[] keys)
 63         {
 64             this.Keys = keys;
 65         }
 66         /// <summary>
 67 /// 构造器
 68 /// </summary>
 69 /// <param name="keys">过滤的关键字</param>
 70 /// <param name="replaceChat">代替过滤掉的字符串</param>
 71         public Filter(string[] keys, string replaceChat)
 72         {
 73             this.Keys = keys;
 74             this.ReplaceChat = replaceChat;
 75         }
 76 
 77         /// <summary>
 78 /// 开始过滤工作
 79 /// </summary>
 80 /// <returns>过滤成功后的字符串</returns>
 81         public string Replace(string content)
 82         {
 83             if (content == null || this.KeysDictionary.Count == 0)
 84             {
 85                 return content;
 86             }
 87             else
 88             {
 89                 int len = content.Length;
 90                 StringBuilder newContent = new StringBuilder(content.Length);//用来放新的结果
 91 //开始每个字来过滤
 92                 for (int num = 0; num < len; num++)
 93                 {
 94                     Dictionary<char, object> dictionary = this.KeysDictionary;
 95                     int n = 0;//表达已经匹配到一个关键词里的几个字符了
 96                     bool isMatch = false;//是否匹配成功
 97                     char c = content[num];
 98                     //通过循环来检查是否匹配关键词
 99                     while (dictionary.ContainsKey(ToUpper(c)))
100                     {
101                         n++;
102                         dictionary = dictionary[ToUpper(c)] as Dictionary<char, object>;
103                         if (dictionary.ContainsKey('\0'))//说明完全匹配到一个关键词
104                         {
105                             for (int i = 0; i < n; i++)
106                             {
107                                 newContent.Append(this.ReplaceChat);
108                             }
109                             num += n-1;       
110                             isMatch = true;
111                             break;
112                         }
113                         else//说明还没有完全匹配到一个关键词
114                         {
115                             if (num + n < len)//说明还没完全匹配到一个关键词,且还可以向下再取一个
116                             {
117                                 c = content[num + n];
118                             }
119                             else//说明已经不能再向下取一个了
120                             {
121                                 break;
122                             }
123                         }
124                     }
125                     if (! isMatch)
126                     {
127                         newContent.Append(content[num]);
128                     }
129                 }
130                 return newContent.ToString();
131             }
132         }
133 
134         /// <summary>
135 /// 将字符转换成大写
136 /// </summary>
137 /// <param name="c">要转换的字符</param>
138 /// <returns>大写后的字符</returns>
139         private char ToUpper(char c)
140         {
141             if (c >= 'a' && c <= 'z')
142             {
143                 return Convert.ToChar(c - 32);
144             }
145             return c;
146         }
147     }
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posted on 2012-01-25 00:51 风里的叶子阅读(200) 评论(0) 收藏举报