Escaping xpath query

node name in xpath query cannot start with numbers:
https://issues.apache.org/jira/browse/JCR-579

So, use org.apache.jackrabbit.util.ISO9075 as shown in:
http://wiki.apache.org/jackrabbit/EncodingAndEscaping

Example xpath servlet (/apps/sandbox/xpath/xpath.jsp):
https://gist.github.com/1478007

<%--

runs xpath

--%><%@page

language="java" 

contentType="text/plain; charset=UTF-8"

pageEncoding="UTF-8"

import="javax.jcr.query.*,

java.io.*,

java.util.*,

java.util.regex.*,

org.apache.jackrabbit.util.*"

%><%@include file="/libs/foundation/global.jsp"%><%!

private static Pattern XPATH = Pattern.compile("^/jcr:root(/.+)//(.+)$");

public static String escapeXpath(String xpath) {

    final Matcher matcher = XPATH.matcher(xpath);

    if (matcher.find()) {

        final String path = ISO9075.encodePath(matcher.group(1));

        final String props = matcher.group(2);

        return String.format("/jcr:root%s//%s", path, props);

    } 

    return xpath;

}

%><%

final String xpathOriginal = slingRequest.getParameter("xpath");

final String xpath = escapeXpath(xpathOriginal);

final boolean isXpathEscaped = !xpath.equals(xpathOriginal);

final String displayParam = slingRequest.getParameter("display");

final boolean display = "false".equals(displayParam) ? false : true;//by default, iterates query result.

final QueryManager queryManager = resourceResolver.adaptTo(Session.class).getWorkspace().getQueryManager();

final Query query = queryManager.createQuery(xpath, Query.XPATH);

final String limitParam = slingRequest.getParameter("limit");

final long limit = (null != limitParam && !"".equals(limitParam)) ? Long.parseLong(limitParam, 10) : 100;

query.setLimit(limit);

final String offsetParam = slingRequest.getParameter("offset"); 

final long offset = (null != offsetParam && !"".equals(offsetParam)) ?  Long.parseLong(offsetParam, 10) : -1;

if (offset > 0) {

    query.setOffset(offset);

}

final long t = System.currentTimeMillis();

final QueryResult result = query.execute();

final NodeIterator iter = result.getNodes();

long count = iter.getSize();

out.append("original xpath:\n");

out.append(xpathOriginal + "\n");

out.append("escaped xpath:\n");

out.append(xpath + "\n");

if (isXpathEscaped) {

    out.append("(xpath is escaped)\n");

}

out.append("\nresult:\n\n");

if (display) {

    count = 0;

    while (iter.hasNext()) {

        final Node node = iter.nextNode();

        out.append(node.getPath() + "\n");

        count++;

    }

}

final long took = System.currentTimeMillis() - t;

%>

queried <%= count %> nodes (offset: <%= offset %>, limit: <%= limit %>) in <%= (took / 1000.0) %> secs.