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

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; } }}

引用：

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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