How do I load an org.w3c.dom.Document from XML in a string?

Question

I have a complete XML document in a string and would like a Document object. Google turns up all sorts of garbage. What is the simplest solution? (In Java 1.5)

Solution Thanks to Matt McMinn, I have settled on this implementation. It has the right level of input flexibility and exception granularity for me. (It's good to know if the error came from malformed XML - SAXException - or just bad IO - IOException.)

public static org.w3c.dom.Document loadXMLFrom(String xml)
    throws org.xml.sax.SAXException, java.io.IOException {
    return loadXMLFrom(new java.io.ByteArrayInputStream(xml.getBytes()));
}

public static org.w3c.dom.Document loadXMLFrom(java.io.InputStream is) 
    throws org.xml.sax.SAXException, java.io.IOException {
    javax.xml.parsers.DocumentBuilderFactory factory =
        javax.xml.parsers.DocumentBuilderFactory.newInstance();
    factory.setNamespaceAware(true);
    javax.xml.parsers.DocumentBuilder builder = null;
    try {
        builder = factory.newDocumentBuilder();
    }
    catch (javax.xml.parsers.ParserConfigurationException ex) {
    }  
    org.w3c.dom.Document doc = builder.parse(is);
    is.close();
    return doc;
}

It would be nice if you can correct the solution. Using String.getByptes and InputStream impose i18n problems. One of my friend got the code from here as is which is wrong. Lucky that findbugs detected the issue. The correct solution provided by erickson is to use InputSource. — Kenneth Xu, Aug 16 '13 at 19:46

score 157 · Answer 1 · answered Aug 28 '08 at 23:16

157

Whoa there!

There's a potentially serious problem with this code, because it ignores the character encoding specified in the String (which is UTF-8 by default). When you call String.getBytes() the platform default encoding is used to encode Unicode characters to bytes. So, the parser may think it's getting UTF-8 data when in fact it's getting EBCDIC or something… not pretty!

Instead, use the parse method that takes an InputSource, which can be constructed with a Reader, like this:

import java.io.StringReader;
import org.xml.sax.InputSource;
…
        return builder.parse(new InputSource(new StringReader(xml)));

It may not seem like a big deal, but ignorance of character encoding issues leads to insidious code rot akin to y2k.

answered Aug 28 '08 at 23:16

erickson

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3

So simple but so elusive a solution on Google. Thank you +1 – pat8719 Feb 15 '12 at 23:14
6

I realize now that I shouldn't just copy-and-paste the accepted answer but rather read through. – Vitaly Sazanovich Nov 13 '13 at 17:45
1

Awesome! Saved our lives on JDK8 with following setup file.encoding=ISO-8859_1 , javax.servlet.request.encoding=UTF-8 PS the answer labeled as correct didnt work for us – kosta5 Apr 12 '17 at 12:08

score 83 · Accepted Answer · answered Aug 28 '08 at 20:11

83

This works for me in Java 1.5 - I stripped out specific exceptions for readability.

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Document;
import java.io.ByteArrayInputStream;

public Document loadXMLFromString(String xml) throws Exception
{
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

    factory.setNamespaceAware(true);
    DocumentBuilder builder = factory.newDocumentBuilder();

    return builder.parse(new ByteArrayInputStream(xml.getBytes()));
}

answered Aug 28 '08 at 20:11

Matt McMinn

15,983
17
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29

As noted in sylvarking's answer, this code uses `getBytes()` with no consideration for encoding. – McDowell Nov 24 '09 at 11:11
2

do you mean erickson's answer? or maybe he renamed his profile? – rogerdpack Dec 04 '12 at 20:57
1

shouldn't there be casting `return (Document) builder.parse(new ByteArrayInputStream(xml.getBytes()));`?? – Rookie Programmer Aravind Jan 16 '13 at 14:10

shsteimer · Answer 3 · 2008-09-05T19:35:57.337

Just had a similar problem, except i needed a NodeList and not a Document, here's what I came up with. It's mostly the same solution as before, augmented to get the root element down as a NodeList and using erickson's suggestion of using an InputSource instead for character encoding issues.

private String DOC_ROOT="root";
String xml=getXmlString();
Document xmlDoc=loadXMLFrom(xml);
Element template=xmlDoc.getDocumentElement();
NodeList nodes=xmlDoc.getElementsByTagName(DOC_ROOT);

public static Document loadXMLFrom(String xml) throws Exception {
        InputSource is= new InputSource(new StringReader(xml));
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware(true);
        DocumentBuilder builder = null;
        builder = factory.newDocumentBuilder();
        Document doc = builder.parse(is);
        return doc;
    }

score 2 · Answer 4 · answered Aug 05 '14 at 11:01

To manipulate XML in Java, I always tend to use the Transformer API:

import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.stream.StreamSource;

public static Document loadXMLFrom(String xml) throws TransformerException {
    Source source = new StreamSource(new StringReader(xml));
    DOMResult result = new DOMResult();
    TransformerFactory.newInstance().newTransformer().transform(source , result);
    return (Document) result.getNode();
}

How do I load an org.w3c.dom.Document from XML in a string?

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