问题
I am using stax for the first time to parse an XML String. I have found some examples but can't get my code to work. This is the latest version of my code:
public class AddressResponseParser
{
private static final String STATUS = "status";
private static final String ADDRESS_ID = "address_id";
private static final String CIVIC_ADDRESS = "civic_address";
String status = null;
String addressId = null;
String civicAddress = null;
public static AddressResponse parseAddressResponse(String response)
{
try
{
byte[] byteArray = response.getBytes("UTF-8");
ByteArrayInputStream inputStream = new ByteArrayInputStream(byteArray);
XMLInputFactory inputFactory = XMLInputFactory.newInstance();
XMLStreamReader reader = inputFactory.createXMLStreamReader(inputStream);
while (reader.hasNext())
{
int event = reader.next();
if (event == XMLStreamConstants.START_ELEMENT)
{
String element = reader.getLocalName();
if (element.equals(STATUS))
{
status = reader.getElementText();
continue;
}
if (element.equals(ADDRESS_ID))
{
addressId = reader.getText();
continue;
}
if (element.equals(CIVIC_ADDRESS))
{
civicAddress = reader.getText();
continue;
}
}
}
}
catch (Exception e)
{
log.error("Couldn't parse AddressResponse", e);
}
}
}
I've put watches on "event" and "reader.getElementText()". When the code is stopped on
String element = reader.getLocalName();
the "reader.getElementText()" value is displayed, but as soon as it moves away from that line it can't be evaluated. When the code is stopped on:
status = reader.getElementText();
the "element" watch displays the correct value. Finally, when I step the code one more line, I catch this exception:
(com.ctc.wstx.exc.WstxParsingException) com.ctc.wstx.exc.WstxParsingException: Current state not START_ELEMENT
at [row,col {unknown-source}]: [1,29]
I've tried using status = reader.getText(); instead, but then I get this exception:
(java.lang.IllegalStateException) java.lang.IllegalStateException: Not a textual event (END_ELEMENT)
Can somebody point out what I'm doing wrong??
EDIT:
Adding JUnit code used to test:
public class AddressResponseParserTest
{
private String status = "OK";
private String address_id = "123456";
private String civic_address = "727";
@Test
public void testAddressResponseParser() throws UnsupportedEncodingException, XMLStreamException
{
AddressResponse parsedResponse = AddressResponseParser.parseAddressResponse(this.responseXML());
assertEquals(this.status, parsedResponse.getStatus());
assertEquals(this.address_id, parsedResponse.getAddress()
.getAddressId());
assertEquals(this.civic_address, parsedResponse.getAddress()
.getCivicAddress());
}
private String responseXML()
{
StringBuffer buffer = new StringBuffer();
buffer.append("<response>");
buffer.append("<status>OK</status>");
buffer.append("<address>");
buffer.append("<address_id>123456</address_id>");
buffer.append("<civic_address>727</civic_address>");
buffer.append("</address>");
buffer.append("</response>");
return buffer.toString();
}
}
回答1:
I found a solution that uses XMLEventReader instead of XMLStreamReader:
public MyObject parseXML(String xml)
throws XMLStreamException, UnsupportedEncodingException
{
byte[] byteArray = xml.getBytes("UTF-8");
ByteArrayInputStream inputStream = new ByteArrayInputStream(byteArray);
XMLInputFactory inputFactory = XMLInputFactory.newInstance();
XMLEventReader reader = inputFactory.createXMLEventReader(inputStream);
MyObject object = new MyObject();
while (reader.hasNext())
{
XMLEvent event = (XMLEvent) reader.next();
if (event.isStartElement())
{
StartElement element = event.asStartElement();
if (element.getName().getLocalPart().equals("ElementOne"))
{
event = (XMLEvent) reader.next();
if (event.isCharacters())
{
String elementOne = event.asCharacters().getData();
object.setElementOne(elementOne);
}
continue;
}
if (element.getName().getLocalPart().equals("ElementTwo"))
{
event = (XMLEvent) reader.next();
if (event.isCharacters())
{
String elementTwo = event.asCharacters().getData();
object.setElementTwo(elementTwo);
}
continue;
}
}
}
return object;
}
I would still be interested in seeing a solution using XMLStreamReader.
回答2:
Make sure you read javadocs for Stax: since it is fully streaming parsing mode, only information contained by the current event is available. There are some exceptions, however; getElementText() for example must start at START_ELEMENT, but will then try to combine all textual tokens from inside current element; and when returning, it will point to matching END_ELEMENT.
Conversely, getText() on START_ELEMENT will not returning anything useful (since START_ELEMENT refers to tag, not child text tokens/nodes 'inside' start/end element pair). If you want to use it instead, you have to explicitly move cursor in stream by calling streamReader.next(); whereas getElementText() does it for you.
So what is causing the error? After you have consumed all start/end-element pairs, next token will be END_ELEMENT (matching whatever was the parent tag). So you must check for the case where you get END_ELEMENT, instead of yet another START_ELEMENT.
回答3:
I faced a similar issue as I was getting "IllegalStateException: Not a textual event" message When I looked through your code I figured out that if you had a condition:
if (event == XMLStreamConstants.START_ELEMENT){
....
addressId = reader.getText(); // it throws exception here
....
}
(Please note: StaXMan did point out this in his answer!)
This happens since to fetch text, XMLStreamReader instance must have encountered 'XMLStreamConstants.CHARACTERS' event!
There maybe a better way to do this...but this is a quick and dirty fix (I have only shown lines of code that may be of interest) Now to make this happen modify your code slightly:
// this will tell the XMLStreamReader that it is appropriate to read the text
boolean pickupText = false
while(reader.hasNext()){
if (event == XMLStreamConstants.START_ELEMENT){
if( (reader.getLocalName().equals(STATUS) )
|| ( (reader.getLocalName().equals(STATUS) )
|| ((reader.getLocalName().equals(STATUS) ))
// indicate the reader that it has to pick text soon!
pickupText = true;
}
}else if (event == XMLStreamConstants.CHARACTERS){
String textFromXML = reader.getText();
// process textFromXML ...
//...
//set pickUpText false
pickupText = false;
}
}
Hope that helps!
回答4:
Here is an example with XMLStreamReader:
XMLInputFactory inputFactory = XMLInputFactory.newInstance();
try {
XMLStreamReader xmlReader = inputFactory.createXMLStreamReader(file);
String elementValue = "";
while (xmlReader.hasNext()) {
int xmlEventType = xmlReader.next();
switch (xmlEventType) {
// Check for Start Elements
case XMLStreamConstants.START_ELEMENT:
//Get current Element Name
String elementName = xmlReader.getLocalName();
if(elementName.equals("td")) {
//Get Elements Value
elementValue = xmlReader.getElementText();
}
//Add the new Start Element to the Map
elements.put(elementName, elementValue);
break;
default:
break;
}
}
//Close Session
xmlReader.close();
} catch (Exception e) {
log.error(e.getMessage(), e);
}
来源：https://stackoverflow.com/questions/4652299/read-xml-string-using-stax