VTD-XML和Xpath 2.0转义字符串

Question

When I try to running the following xpath expression in Java using VTD-XML I get an unexpected error.

Code:

..
AutoPilot ap = new AutoPilot(vn);
ap.selectXPath("/a//b[text() = 'apple''banana']");

Error:

Syntax error after or around the end of ==> /a//b[text() = 'apple'
Caused by: com.ximpleware.XPathParseException: XPath Syntax error: #29
    at com.ximpleware.xpath.parser.unrecovered_syntax_error(parser.java:492)
    at java_cup.runtime.lr_parser.parse(lr_parser.java:601)
    at com.ximpleware.AutoPilot.selectXPath(AutoPilot.java:809)

Is this not a bug? I was under the impression that escaping single quotes in XPath 2.0 was acceptable? When I try running the xpath query in XML Spy with the same document it runs fine.

Answer 1

由于XPath还支持".."字符串，其中可以包含未转义的'-s，因此您可以使用：

   ap.selectXPath("/a//b[text() = \"apple'banana\"]");

Answer 2

Escaping is a matter that is entirely left to the host language that uses XPath to query data. The escaping rules of that higher-level language usually also apply to XPath expressions used therein.

I quote from Michael Kay's XPath 2.0 Programmer's Reference:

Similarly, when XPath expressions are written within character strings in a host language such as Java, you will need to use the escaping conventions of that language: for example, [...] a quotation mark as \\" .

In other words, '' does escape a single quote, in XSLT 2.0 . In Java, the single quote must be escaped as \\' I guess.

ap.selectXPath("/a//b[text() = 'apple\'banana']");

Answer 3

Unfortunately it looks like escaping isn't an option, I had to write a custom function based on the following:

XQuery looking for text with 'single' quote

It was written in javascript so I converted it to Java:

private static String cleanStringForXPath(String dirtyString)
    {
        Pattern pattern = Pattern.compile("([^'\"]+|['\"])");
        Matcher matcher = pattern.matcher(dirtyString);

        int count = 0;
        StringBuilder sb = new StringBuilder();

        while(matcher.find()) {
            String part = matcher.group(1);
            if(part.equals("'")) {
                sb.append("\"'\"");
            } else if(part.equals("\"")) {
                sb.append("'\"'");
            } else { 
                sb.append("'" + part + "'");
            }
            sb.append(",");
            count++;
        }

    String result = sb.length() > 0 ? sb.substring(0, sb.length() - 1): "";
    return (count > 1) ? "concat(" + result + ")" : result;
}

I tested this function and it seems to resolve my problem.