How can I validate XML using java?
I need to parse a bunch of incoming XML documents, but it doesn't contain a DOCTYPE (they all have different DTDs). DTD is created by me. How can I validate an XML file against a DTD that is stored locally as a file? I have the following requirement:
- All DTDs (for different XML) will be loaded into memory once, when the incoming XML is not viewed in the locally stored scope.
- validate incoming XML based on the loaded DTD file.
thank
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1 answer
For the SAX parser, you need to use a local entity resolver, here is an example of its implementation:
class LocalEntityResolver implements EntityResolver {
private static final Logger LOG = ESAPI.getLogger(LocalEntityResolver.class);
private static final Map<String, String> DTDS;
static {
DTDS = new HashMap<String, String>();
DTDS.put("-//W3C//DTD XHTML 1.0 Transitional//EN",
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd");
DTDS.put("-//W3C//ENTITIES Latin 1 for XHTML//EN",
"http://www.w3.org/TR/xhtml1/DTD/xhtml-lat1.ent");
DTDS.put("-//W3C//ENTITIES Symbols for XHTML//EN",
"http://www.w3.org/TR/xhtml1/DTD/xhtml-symbol.ent");
DTDS.put("-//W3C//ENTITIES Special for XHTML//EN",
"http://www.w3.org/TR/xhtml1/DTD/xhtml-special.ent");
}
@Override
public InputSource resolveEntity(String publicId, String systemId)
throws SAXException, IOException {
InputSource input_source = null;
if (publicId != null && DTDS.containsKey(publicId)) {
LOG.debug(Logger.EVENT_SUCCESS, "Looking for local copy of [" + publicId + "]");
final String dtd_system_id = DTDS.get(publicId);
final String file_name = dtd_system_id.substring(
dtd_system_id.lastIndexOf('/') + 1, dtd_system_id.length());
InputStream input_stream = FileUtil.readStreamFromClasspath(
file_name, "your/dtd/location",
getClass().getClassLoader());
if (input_stream != null) {
LOG.debug(Logger.EVENT_SUCCESS, "Found local file [" + file_name + "]!");
input_source = new InputSource(input_stream);
}
}
return input_source;
}
}
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