code: private synchronized static Pattern getPattern(String tagName,
  			String attrName) {
  
  		String key = tagName + "    " + attrName;
  		Pattern pc = pcPatterns.get(key);
  		if (pc == null) {
  
  			String tagPatString = "<\\s*" + tagName + "\\s+[^>]*\\b" + attrName
  					+ "\\s*=\\s*(" + ANY_ATTR_VALUE + ")(?:\\s|>)?";
  
  			pc = Pattern.compile(tagPatString, Pattern.CASE_INSENSITIVE);
  			pcPatterns.put(key, pc);
  		}
  		return pc;
  	}
docs: get (and cache) a regex Pattern for locating an HTML attribute value
  within a particular tag. if found, the pattern will have the attribute
  value in group 1. Note that the attribute value may contain surrounding
  apostrophe(') or quote(") characters.
  
  @param tagName
  @param attrName
  @return Pattern to match the tag-attribute's value