获取XML根节点名称

package com.chris.regex;

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

public class XMLRootSearcher {

	public String findRootElementName(String xml) {
		String result = null;

		Pattern regex = null;
		Matcher acceptor = null;

		try {
			// http://www.w3.org/TR/2004/REC-xml11-20040204/#NT-Name
			// Name ::= NameStartChar (NameChar)*
			String namePattern = "<(([:_A-Za-z\\xC0-\\xD6\\xD8-\\xF6\\xF8-\\u02FF"
					+ "\\u0370-\\u037D\\u037F-\\u1FFF\\u200C-\\u200D"
					+ "\\u2070-\\u218F\\u2C00-\\u2FEF\\u3001-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFFD"
					+ "])([:_A-Za-z0-9\\."
					+ "\\xB7\\xC0-\\xD6\\xD8-\\xF6\\xF8-\\u02FF\\u0370-\\u037D"
					+ "\\u0300-\\u036F\\u037F-\\u1FFF\\u200C-\\u200D"
					+ "\\u203F-\\u2040\\u2070-\\u218F\\u2C00-\\u2FEF\\u3001-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFFD"
					+ "\\-])*)";

			regex = Pattern.compile(namePattern, Pattern.CANON_EQ);

			acceptor = regex.matcher(xml);
		} catch (PatternSyntaxException pse) {
			pse.printStackTrace(System.err);

			return result;
		}

		if (acceptor.find()) {
			if (null != acceptor.group(1)) {
				result = acceptor.group(1);
			}
		}

		return result;
	}
	
	public static void main(String[] args) {
		
		String xmlStr = "<?xml version=\"1.0\" encoding=\"utf-8\"?><books><book></book></books>";
		XMLRootSearcher searcher = new XMLRootSearcher();
		System.out.println( searcher.findRootElementName( xmlStr ) );
		
	}

}

运行结果:

books