本文实例讲述了高效.NET脏字过滤算法。分享给大家供大家参考，具体如下：
BadWordsFilter.cs类
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Collections;
using System.Data;
namespace WNF
{
public class BadWordsFilter
{
private HashSet<string> hash = new HashSet<string>(); //关键字
private byte[] fastCheck = new byte[char.MaxValue];
private byte[] fastLength = new byte[char.MaxValue];
private BitArray charCheck = new BitArray(char.MaxValue);
private BitArray endCheck = new BitArray(char.MaxValue);
private int maxWordLength = 0;
private int minWordLength = int.MaxValue;
public BadWordsFilter()
{
}
//初始化关键字
public void Init(DataTable badwords)
{
for (int j = 0; j < badwords.Rows.Count; j++)
{
string word = badwords.Rows[j][0].ToString();
maxWordLength = Math.Max(maxWordLength, word.Length);
minWordLength = Math.Min(minWordLength, word.Length);
for (int i = 0; i < 7 && i < word.Length; i++)
{
fastCheck[word[i]] |= (byte)(1 << i);
}
for (int i = 7; i < word.Length; i++)
{
fastCheck[word[i]] |= 0x80;
}
if (word.Length == 1)
{
charCheck[word[0]] = true;
}
else
{
fastLength[word[0]] |= (byte)(1 << (Math.Min(7, word.Length - 2)));
endCheck[word[word.Length - 1]] = true;
hash.Add(word);
}
}
}
public string Filter(string text, string mask)
{
throw new NotImplementedException();
}
//检查是否有关键字
public bool HasBadWord(string text)
{
int index = 0;
while (index < text.Length)
{
int count = 1;
if (index > 0 || (fastCheck[text[index]] & 1) == 0)
{
while (index < text.Length - 1 && (fastCheck[text[++index]] & 1) == 0) ;
}
char begin = text[index];
if (minWordLength == 1 && charCheck[begin])
{
return true;
}
for (int j = 1; j <= Math.Min(maxWordLength, text.Length - index - 1); j++)
{
char current = text[index + j];
if ((fastCheck[current] & 1) == 0)
{
++count;
}
if ((fastCheck[current] & (1 << Math.Min(j, 7))) == 0)
{
break;
}
if (j + 1 >= minWordLength)
{
if ((fastLength[begin] & (1 << Math.Min(j - 1, 7))) > 0 && endCheck[current])
{
string sub = text.Substring(index, j + 1);
if (hash.Contains(sub))
{
return true;
}
}
}
}
index += count;
}
return false;
}
}
}
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引用：
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string sql = "select keywords from tb_keyword";
BadWordsFilter badwordfilter = new BadWordsFilter();
//初始化关键字
badwordfilter.Init(oEtb.GetDataSet(sql).Tables[0]);
//检查是否有存在关键字
bool a = badwordfilter.HasBadWord(TextBox1.Text);
if (a == true)
{
Page.RegisterClientScriptBlock("a", "<script>alert('该评论含有不合法文字！')</script>");
}
else
{
PingLun();//写入评论表
}
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希望本文所述对大家asp.net程序设计有所帮助。