public static String xmlTagCapitalize(String xmlStr) {
    	String regex = "<(/*[A-Za-z]+)>";
    	Matcher matcher = Pattern.compile(regex).matcher(xmlStr);
    	StringBuffer sb = new StringBuffer();
    	while (matcher.find()) {
    		String str = matcher.group(1);
    		if(!str.startsWith("/")) {
    			matcher.appendReplacement(sb, "<" + (StringUtil.capitalize (str)) + ">");
    		}else {
    			matcher.appendReplacement(sb, "</" + (StringUtil.capitalize (str.substring(1, str.length()))) + ">");
    		}
    		
    	}
    	matcher.appendTail(sb);
    	return sb.toString();
    }
 

https://my.oschina.net/svili/blog/777507