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社区首页 >问答首页 >使用Jettison在Java中从JSON到DOM

问使用Jettison在Java中从JSON到DOM
EN

Stack Overflow用户
提问于 2009-05-12 19:09:53
回答 3查看 4.9K关注 0票数 3

到目前为止，这是一个失败的故事，任何建议都是值得欢迎的。我尝试了以下几点：

使用JAXP与撒克逊一起使用XMLStreamReader编写文档

守则：

代码语言：javascript
复制
JSONObject obj = new JSONObject("{\"alice\":{\"bob\": \"a\"}}");
AbstractXMLStreamReader reader = new MappedXMLStreamReader(obj);

StAXSource source = new StAXSource(reader);
Document document = XMLUtils.createDocument();
DOMResult result = new DOMResult(document);
Transformer identity = TransformerUtils.getIdentityTransformer();
identity.transform(source, result);
result.getNode();

这是因为我们使用的撒克逊转换器不支持StAXSource，所以失败了。例外是：

代码语言：javascript
复制
org.orbeon.saxon.trans.DynamicError: A source of type javax.xml.transform.stax.StAXSource is not supported in this environment
    org.orbeon.saxon.event.Sender.send(Sender.java:185)
    org.orbeon.saxon.IdentityTransformer.transform(IdentityTransformer.java:29)
    org.orbeon.oxf.xml.TransformerWrapper.transform(TransformerUtils.java:597)
    org.apache.jsp.gaga_jsp._jspService(gaga_jsp.java:93)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

使用JAXP和XMLStreamReader编写文档

守则：

代码语言：javascript
复制
JSONObject obj = new JSONObject("{\"alice\":{\"bob\": \"a\"}}");
AbstractXMLStreamReader reader = new MappedXMLStreamReader(obj);

StAXSource source = new StAXSource(reader);
Document document = XMLUtils.createDocument();
DOMResult result = new DOMResult(document);
Transformer identity = orbeon.apache.xalan.processor.TransformerFactoryImpl.newInstance().newTransformer();
identity.transform(source, result);
result.getNode();

这在Xalan2.5.1(我们使用的版本)中失败了。最新的版本是2.7.1，也许他们在该版本中增加了对StAXSource的支持。

代码语言：javascript
复制
javax.xml.transform.TransformerException: Can't transform a Source of type javax.xml.transform.stax.StAXSource
    orbeon.apache.xalan.transformer.TransformerIdentityImpl.transform(TransformerIdentityImpl.java:372)
    org.apache.jsp.gaga_jsp._jspService(gaga_jsp.java:82)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

使用XMLStreamReader和DOMResult编写文档

守则：

代码语言：javascript
复制
JSONObject obj = new JSONObject("{\"alice\":{\"bob\": \"a\"}}");
AbstractXMLStreamReader streamReader = new MappedXMLStreamReader(obj);
XMLInputFactory readerFactory = XMLInputFactory.newInstance();
XMLEventReader eventReader = readerFactory.createXMLEventReader(streamReader);

Document document = XMLUtils.createDocument();
DOMResult result = new DOMResult(document);
XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();
XMLEventWriter eventWriter = outputFactory.createXMLEventWriter(result);
eventWriter.add(eventReader);
eventWriter.close();

result.getNode();

这一条导致了Xerces中的NPE：

代码语言：javascript
复制
java.lang.NullPointerException
    orbeon.apache.xerces.dom.CoreDocumentImpl.setXmlVersion(CoreDocumentImpl.java:850)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    java.lang.reflect.Method.invoke(Method.java:597)
    com.sun.xml.internal.stream.writers.XMLDOMWriterImpl.writeStartDocument(XMLDOMWriterImpl.java:583)
    com.sun.xml.internal.stream.writers.XMLEventWriterImpl.add(XMLEventWriterImpl.java:96)
    com.sun.xml.internal.stream.writers.XMLEventWriterImpl.add(XMLEventWriterImpl.java:72)
    org.apache.jsp.gaga_jsp._jspService(gaga_jsp.java:95)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

使用XMLStreamReader和Writer编写文档

守则：

代码语言：javascript
复制
JSONObject obj = new JSONObject("{\"alice\": {\"bob\": \"a\"}}");
AbstractXMLStreamReader streamReader = new MappedXMLStreamReader(obj);
XMLInputFactory readerFactory = XMLInputFactory.newInstance();
XMLEventReader eventReader = readerFactory.createXMLEventReader(streamReader);

StringWriter stringWriter = new StringWriter();
XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();
XMLEventWriter eventWriter = outputFactory.createXMLEventWriter(stringWriter);
eventWriter.add(eventReader);
eventWriter.close();

out.print(stringWriter.toString());

使用Java 5，它查找找不到的com.bea.xml.stream.MXParserFactory：

代码语言：javascript
复制
javax.xml.stream.FactoryConfigurationError: Provider com.bea.xml.stream.MXParserFactory not found
    javax.xml.stream.FactoryFinder.newInstance(FactoryFinder.java:72)
    javax.xml.stream.FactoryFinder.find(FactoryFinder.java:178)
    javax.xml.stream.FactoryFinder.find(FactoryFinder.java:92)
    javax.xml.stream.XMLInputFactory.newInstance(XMLInputFactory.java:136)
    org.apache.jsp.gaga_jsp._jspService(gaga_jsp.java:79)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

使用Java 6，它将导致Sun的XMLEventAllocatorImpl中的NPE

代码语言：javascript
复制
java.lang.NullPointerException
    com.sun.xml.internal.stream.events.XMLEventAllocatorImpl.getXMLEvent(XMLEventAllocatorImpl.java:82)
    com.sun.xml.internal.stream.events.XMLEventAllocatorImpl.allocate(XMLEventAllocatorImpl.java:55)
    com.sun.xml.internal.stream.XMLEventReaderImpl.nextEvent(XMLEventReaderImpl.java:86)
    com.sun.xml.internal.stream.writers.XMLEventWriterImpl.add(XMLEventWriterImpl.java:72)
    org.apache.jsp.gaga_jsp._jspService(gaga_jsp.java:85)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

使用BadgerFishDOMDocumentParser

代码：

代码语言：javascript
复制
ByteArrayInputStream bais = new ByteArrayInputStream("{\"alice\": {\"bob\": \"a\"}}".getBytes());
Document resDOM = new BadgerFishDOMDocumentParser().parse(bais);

这一次给出了Sun's XMLEventAllocatorImpl中的NPE

代码语言：javascript
复制
java.lang.NullPointerException
    com.sun.xml.internal.stream.events.XMLEventAllocatorImpl.getXMLEvent(XMLEventAllocatorImpl.java:82)
    com.sun.xml.internal.stream.events.XMLEventAllocatorImpl.allocate(XMLEventAllocatorImpl.java:55)
    com.sun.xml.internal.stream.XMLEventReaderImpl.nextEvent(XMLEventReaderImpl.java:86)
    com.sun.xml.internal.stream.writers.XMLEventWriterImpl.add(XMLEventWriterImpl.java:72)
    org.codehaus.jettison.AbstractDOMDocumentParser.parse(AbstractDOMDocumentParser.java:66)
    org.apache.jsp.gaga_jsp._jspService(gaga_jsp.java:79)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
json
dom
jettison
java
xml
EN

回答 3

Stack Overflow用户

发布于 2009-07-06 23:58:41

不，我不认为Xalan支持Stax，因为某种原因。撒克逊是这样做的，所以您可以尝试一下吗？

但是如果不是，也许您应该使用链接文本 (如这篇文章解释)从Stax构建一个DOM树？Xalan确实接受DOM源作为输入。

票数 1
EN

Stack Overflow用户

发布于 2009-05-12 20:26:04

JSON不是XML --看起来您试图使用XML解析器解析JSON对象吗？不过，我可能误解了你说的话。

票数 0
EN

Stack Overflow用户

发布于 2011-11-05 23:05:30

我也有这个问题，经历了和行动一样的挫折。有人提到这种行为是某个woodstox邮件列表中的一个bug。不过，我还是想出了解决办法。我编写了一个非常基本的XMLEventReader，它封装了一个XMLStreamReader，它做得很好。两个重要的注意事项: 1)这个代码是按原样提供的；具体来说，除了我自己有限的使用之外，我还没有对它进行彻底的测试；2)这个问题在互联网上几乎不存在，而且这似乎是一个相对基本的操作，抛弃应该执行，这强烈地告诉我，我们正在做一些根本错误的事情，这个解决方案不应该是必要的。用你自己的判断。

首先，下面是一个工作的XMLEventReader：

代码语言：javascript
复制
import java.util.LinkedList;
import java.util.Queue;

import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.events.XMLEvent;

import com.sun.xml.internal.stream.events.AttributeImpl;
import com.sun.xml.internal.stream.events.CharacterEvent;
import com.sun.xml.internal.stream.events.CommentEvent;
import com.sun.xml.internal.stream.events.DTDEvent;
import com.sun.xml.internal.stream.events.EndDocumentEvent;
import com.sun.xml.internal.stream.events.EndElementEvent;
import com.sun.xml.internal.stream.events.NamespaceImpl;
import com.sun.xml.internal.stream.events.ProcessingInstructionEvent;
import com.sun.xml.internal.stream.events.StartDocumentEvent;
import com.sun.xml.internal.stream.events.StartElementEvent;

public class WorkingXMLEventReader implements XMLEventReader {

    private final XMLStreamReader streamReader;
    private final Queue<XMLEvent> eventQueue = new LinkedList<XMLEvent>();

    public WorkingXMLEventReader (XMLStreamReader streamReader) {
        this.streamReader = streamReader;
    }

    @Override public Object next () {
        try {
            return nextEvent();
        } catch (XMLStreamException x) {
            return null;
        }
    }

    @Override public void remove () {
        throw new UnsupportedOperationException("WorkingXMLEventReader iterator interface does not support remove()");
    }

    @Override public void close () throws XMLStreamException {
        streamReader.close();
        eventQueue.clear();
    }

    @Override public String getElementText () throws XMLStreamException {
        return streamReader.getElementText();
    }

    @Override public Object getProperty (String key) throws IllegalArgumentException {
        return streamReader.getProperty(key);
    }

    @Override public boolean hasNext () {
        try {
            return !eventQueue.isEmpty() || streamReader.hasNext();
        } catch (XMLStreamException x) {
            return false;
        }
    }

    @Override public XMLEvent nextEvent () throws XMLStreamException {
        if (eventQueue.isEmpty())
            parseEvents(eventQueue, streamReader, streamReader.next());
        return eventQueue.remove();
    }

    @Override public XMLEvent nextTag () throws XMLStreamException {
        if (eventQueue.isEmpty())
            parseEvents(eventQueue, streamReader, streamReader.nextTag());
        return eventQueue.remove();        
    }

    @Override public XMLEvent peek () throws XMLStreamException {
        return eventQueue.peek();
    }

    protected static void parseEvents (Queue<XMLEvent> events, XMLStreamReader reader, int type) {
        switch (type) {
        case XMLEvent.START_ELEMENT: 
            events.add(new StartElementEvent(reader.getName()));
            break;
        case XMLEvent.END_ELEMENT: 
            events.add(new EndElementEvent(reader.getName()));
            break;
        case XMLEvent.CDATA:
            events.add(new CharacterEvent(reader.getText(), true, false));
            break;
        case XMLEvent.SPACE:
            events.add(new CharacterEvent(reader.getText(), false, true));
            break;
        case XMLEvent.CHARACTERS: 
            events.add(new CharacterEvent(reader.getText(), false, false));
            break;
        case XMLEvent.ATTRIBUTE:
            for (int n = 0; n < reader.getAttributeCount(); ++ n) {
                AttributeImpl attr = new AttributeImpl(reader.getAttributePrefix(n), 
                        reader.getAttributeNamespace(n), reader.getAttributeLocalName(n), 
                        reader.getAttributeValue(n), reader.getAttributeType(n));
                events.add(attr);
            }
            break;
        case XMLEvent.NAMESPACE:
            for (int n = 0; n < reader.getNamespaceCount(); ++ n) {
                NamespaceImpl ns = new NamespaceImpl(reader.getNamespacePrefix(n), 
                        reader.getNamespaceURI(n));
                events.add(ns);
            }
            break;
        case XMLEvent.PROCESSING_INSTRUCTION:
            events.add(new ProcessingInstructionEvent(reader.getPITarget(), reader.getPIData()));
            break;
        case XMLEvent.COMMENT:
            events.add(new CommentEvent(reader.getText()));
            break;
        case XMLEvent.START_DOCUMENT:
            events.add(new StartDocumentEvent(reader.getEncoding(), reader.getVersion()));
            break;
        case XMLEvent.END_DOCUMENT:
            events.add(new EndDocumentEvent());
            break;
        case XMLEvent.DTD:
            events.add(new DTDEvent(reader.getText()));
            break;
        }   
    }

}

接下来，下面是如何在OP示例中使用它：

代码语言：javascript
复制
XMLStreamReader streamReader = new MappedXMLStreamReader(new JSONObject("{\"alice\":{\"bob\": \"a\"}}"));
XMLEventReader eventReader = new WorkingXMLEventReader(streamReader);

Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
XMLEventWriter eventWriter = XMLOutputFactory.newInstance().createXMLEventWriter(new DOMResult(document));
eventWriter.add(eventReader);
eventWriter.close();

// test
Source testSource = new DOMSource(document);
Result testResult = new StreamResult(System.out);
TransformerFactory.newInstance().newTransformer().transform(testSource, testResult);

输出应该类似于：

代码语言：javascript
复制
<?xml version="1.0" encoding="UTF-8" standalone="no"?><alice><bob>a</bob></alice>

希望这能帮到别人。

票数 0
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/854344

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