为什么 STAX 解析器认为这是有效的 XML 1.0 而不是

Why does the STAX parser think this is valid XML 1.0 but not 1.1?(为什么 STAX 解析器认为这是有效的 XML 1.0 而不是 1.1?)

问题描述

在下面的代码示例中，我使用 STaX 解析器来解析一段 XML.如果我通过它运行 xml10，它会按预期工作.xml11 字符串(相同，除了 xml 版本) - 它抛出 NullPointerException.我在使用 JDK 1.6 的 Mac 上运行它.

In the following code example, I use the STaX parser to parse a piece of XML. If I run the xml10 through it, it works as expected. The xml11 string (which is the same, except for the xml version) - it throws a NullPointerException. I'm running this on a Mac using JDK 1.6.

import javax.xml.namespace.QName;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamReader;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.StringReader;
import java.util.Stack;

/**
 */
public class StaxSucks {

    static String xml10 ="<?xml version="1.0" encoding="utf-8" ?>
"+
                        "<anElement/>";

    static String xml11 ="<?xml version="1.1" encoding="utf-8" ?>
"+
            "<anElement/>";


    static void parse(InputStream is) throws Exception{
        final XMLInputFactory factory = XMLInputFactory.newInstance();
        factory.setProperty(XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, Boolean.FALSE);
        final XMLStreamReader xmlStreamReader = factory.createXMLStreamReader(is);
        Stack<QName> XMLDEPTH = new Stack<QName>();
        int eventType = xmlStreamReader.next();
        while(eventType != XMLStreamConstants.END_DOCUMENT){
            if(XMLStreamConstants.START_ELEMENT == eventType){
                QName eventName = xmlStreamReader.getName();
                XMLDEPTH.push(eventName);
            }else if(XMLStreamConstants.END_ELEMENT == eventType){
                //ends should always match the starts.
                QName eventName = xmlStreamReader.getName();
                if(XMLDEPTH.peek().equals(eventName)){
                    XMLDEPTH.pop();
                }else{
                    System.out.println("Hit an end with a non-matching beginning:"+eventName);
                }
            } else{
                System.out.println("Hit event type:"+eventType);
            }
            eventType = xmlStreamReader.next();
        }
        System.out.println("Stack is empty:"+XMLDEPTH.empty());

    }

    public static void main(String[] args) throws Exception{
        System.out.println("Starting XML1.0");
        InputStream is = new ByteArrayInputStream(xml10.getBytes("utf8"));
        parse(is);
        System.out.println("Starting XML1.1");
        is = new ByteArrayInputStream(xml11.getBytes("utf8"));
        parse(is);
    }
}

堆栈跟踪:

Exception in thread "main" java.lang.NullPointerException
    at com.sun.org.apache.xerces.internal.impl.XML11NSDocumentScannerImpl.scanStartElement(XML11NSDocumentScannerImpl.java:351)
    at com.sun.org.apache.xerces.internal.impl.XML11NSDocumentScannerImpl$NS11ContentDriver.scanRootElementHook(XML11NSDocumentScannerImpl.java:889)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:3104)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:922)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648)
    at com.sun.org.apache.xerces.internal.impl.XML11NSDocumentScannerImpl.next(XML11NSDocumentScannerImpl.java:852)
    at com.sun.org.apache.xerces.internal.impl.XMLStreamReaderImpl.next(XMLStreamReaderImpl.java:554)
    at StaxSucks.parse(StaxSucks.java:46)
    at StaxSucks.main(StaxSucks.java:74)

推荐答案

您好 这是 Sun/Oracle JDK 中 stax 实现损坏的案例，IBM JDK 工作正常，或者您甚至可以只使用最新的 Xerces jars会没事的.

Hi This is a case of broken stax implementation in the Sun/Oracle JDK, IBM JDK works fine, or you can even just use the latest Xerces jars and you will be fine.

您可以从以下位置下载 xerces jar:http://xerces.apache.org/mirrors.cgi#binary

You can download xerces jars from: http://xerces.apache.org/mirrors.cgi#binary

dims@dims-laptop-520:~/test$ /usr/lib/jvm/java-6-sun/bin/java -cp . StaxSucks
Starting XML1.0
Stack is empty:true
Starting XML1.1
Exception in thread "main" java.lang.NullPointerException
    at com.sun.org.apache.xerces.internal.impl.XML11NSDocumentScannerImpl.scanStartElement(XML11NSDocumentScannerImpl.java:351)
    at com.sun.org.apache.xerces.internal.impl.XML11NSDocumentScannerImpl$NS11ContentDriver.scanRootElementHook(XML11NSDocumentScannerImpl.java:889)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:3104)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:922)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648)
    at com.sun.org.apache.xerces.internal.impl.XML11NSDocumentScannerImpl.next(XML11NSDocumentScannerImpl.java:852)
    at com.sun.org.apache.xerces.internal.impl.XMLStreamReaderImpl.next(XMLStreamReaderImpl.java:554)
    at StaxSucks.parse(StaxSucks.java:26)
    at StaxSucks.main(StaxSucks.java:54)
dims@dims-laptop-520:~/test$ java -cp .:xercesImpl.jar:xml-apis.jar StaxSucks
Starting XML1.0
Stack is empty:true
Starting XML1.1
Stack is empty:true

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