code: private String escape(String str) {
  		if (str == null || str.length() == 0) {
  			return str;
  		}
  		
  		int len = str.length();
  		StringBuilder ret = new StringBuilder(len * 2);
  		for (int i = 0; i < len; i++) {
  			char cur = str.charAt(i);
  			switch (cur) {
  			case '<':
  				ret.append("&lt;");
  				break;
  			case '>':
  				ret.append("&gt;");
  				break;
  			case '"':
  				ret.append("&quot;");
  				break;
  			case '\'':
  				// ret.append("&apos;");	// IE 不支持 &apos; 考虑 &#39;
  				ret.append("&#39;");
  				break;
  			case '&':
  				ret.append("&amp;");
  				break;
  			default:
  				ret.append(cur);
  				break;
  			}
  		}
  
  		return ret.toString();
  	}
docs: TODO 挪到 StrKit 中