案例

import java.util.regex.Matcher;   import java.util.regex.Pattern;     /**   * 
   * Title: HTML相关的正则表达式工具类   * 
   * 
   * Description: 包括过滤HTML标记，转换HTML标记，替换特定HTML标记   * 
   * 
   * Copyright: Copyright (c) 2006   * 
   *    * @author hejian   * @version 1.0   * @createtime 2006-10-16   */    public class HtmlRegexpUtil {       private final static String regxpForHtml = "<([^>]*)>"; // 过滤所有以
     <开头以>
      结尾的标签         private final static String regxpForImgTag = "<\\s*img\\s+([^>]*)\\s*>"; // 找出IMG标签         private final static String regxpForImaTagSrcAttrib = "src=\"([^\"]+)\""; // 找出IMG标签的SRC属性         /**       *        */      public HtmlRegexpUtil() {           // TODO Auto-generated constructor stub       }         /**       *        * 基本功能：替换标记以正常显示       * 
      
       *        * @param input       * @return String       */      public String replaceTag(String input) {           if (!hasSpecialChars(input)) {               return input;           }           StringBuffer filtered = new StringBuffer(input.length());           char c;           for (int i = 0; i <= input.length() - 1; i++) {               c = input.charAt(i);               switch (c) {               case '<':                   filtered.append("<");                   break;               case '>':                   filtered.append(">");                   break;               case '"':                   filtered.append(""");                   break;               case '&':                   filtered.append("&");                   break;               default:                   filtered.append(c);               }             }           return (filtered.toString());       }         /**       *        * 基本功能：判断标记是否存在       * 
      
       *        * @param input       * @return boolean       */      public boolean hasSpecialChars(String input) {           boolean flag = false;           if ((input != null) && (input.length() > 0)) {               char c;               for (int i = 0; i <= input.length() - 1; i++) {                   c = input.charAt(i);                   switch (c) {                   case '>':                       flag = true;                       break;                   case '<':                       flag = true;                       break;                   case '"':                       flag = true;                       break;                   case '&':                       flag = true;                       break;                   }               }           }           return flag;       }         /**       *        * 基本功能：过滤所有以"<"开头以">"结尾的标签       * 
      
       *        * @param str       * @return String       */      public static String filterHtml(String str) {           Pattern pattern = Pattern.compile(regxpForHtml);           Matcher matcher = pattern.matcher(str);           StringBuffer sb = new StringBuffer();           boolean result1 = matcher.find();           while (result1) {               matcher.appendReplacement(sb, "");               result1 = matcher.find();           }           matcher.appendTail(sb);           return sb.toString();       }         /**       *        * 基本功能：过滤指定标签       * 
      
       *        * @param str       * @param tag       *            指定标签       * @return String       */      public static String fiterHtmlTag(String str, String tag) {           String regxp = "<\\s*" + tag + "\\s+([^>]*)\\s*>";           Pattern pattern = Pattern.compile(regxp);           Matcher matcher = pattern.matcher(str);           StringBuffer sb = new StringBuffer();           boolean result1 = matcher.find();           while (result1) {               matcher.appendReplacement(sb, "");               result1 = matcher.find();           }           matcher.appendTail(sb);           return sb.toString();       }         /**       *        * 基本功能：替换指定的标签       * 
      
       *        * @param str       * @param beforeTag       *            要替换的标签       * @param tagAttrib       *            要替换的标签属性值       * @param startTag       *            新标签开始标记       * @param endTag       *            新标签结束标记       * @return String       * @如：替换img标签的src属性值为[img]属性值[/img]       */      public static String replaceHtmlTag(String str, String beforeTag,               String tagAttrib, String startTag, String endTag) {           String regxpForTag = "<\\s*" + beforeTag + "\\s+([^>]*)\\s*>";           String regxpForTagAttrib = tagAttrib + "=\"([^\"]+)\"";           Pattern patternForTag = Pattern.compile(regxpForTag);           Pattern patternForAttrib = Pattern.compile(regxpForTagAttrib);           Matcher matcherForTag = patternForTag.matcher(str);           StringBuffer sb = new StringBuffer();           boolean result = matcherForTag.find();           while (result) {               StringBuffer sbreplace = new StringBuffer();               Matcher matcherForAttrib = patternForAttrib.matcher(matcherForTag                       .group(1));               if (matcherForAttrib.find()) {                   matcherForAttrib.appendReplacement(sbreplace, startTag                           + matcherForAttrib.group(1) + endTag);               }               matcherForTag.appendReplacement(sb, sbreplace.toString());               result = matcherForTag.find();           }           matcherForTag.appendTail(sb);           return sb.toString();       }   }