无法使用SAX读取某些属性 [英] Can't read some attributes with SAX

问题描述

我正在尝试使用SAX解析该文档：

I'm trying to parse that document with SAX:

<scxml version="1.0" initialstate="start" name="calc"> 
  <datamodel> 
      <data id="expr" expr="0" /> 
      <data id="res" expr="0" /> 
  </datamodel> 
  <state id="start"> 
      <transition event="OPER" target="opEntered" /> 
      <transition event="DIGIT" target="operand" /> 
  </state> 
  <state id="operand"> 
      <transition event="OPER" target="opEntered" /> 
      <transition event="DIGIT" /> 
  </state> 
</scxml>

我很好地阅读了所有属性，除了initialstate和name...
我使用startElement处理程序获取属性，但scxml的属性列表的大小为零。为什么？我如何克服这个问题？

I read all the attributes well, except "initialstate" and "name"... I get the attributes with the startElement handler, but the size of the attribute list for scxml is zero. Why? How I can overcome that problem?

编辑：

public void startElement(String uri, String localName, String qName, Attributes attributes){
  System.out.println(attributes.getValue("initialstate"));
  System.out.println(attributes.getValue("name")); 
}

解析第一个标签时不起作用（打印null 两次）。事实上，

that, when parsing the first tag, doesn't work (prints "null" two times). In fact,

attributes.getLength();

评估为零。

谢谢

推荐答案

我有一个完整的例子来自那里并根据你的文件调整它：

I've got a full example working from there and adapted it for your file:

public class SaxParserMain {

    /**
     * @param args
     * @throws SAXException
     * @throws ParserConfigurationException
     * @throws IOException
     */
    public static void main(String[] args) throws ParserConfigurationException, SAXException,
            IOException {
        SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
        CustomHandler handler = new CustomHandler();
        parser.parse(new File("file/scxml.xml"), handler);
    }
}

和

public class CustomHandler extends DefaultHandler {

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes)
            throws SAXException {
        System.out.println();
        System.out.print("<" + qName + "");
        if (attributes.getLength() == 0) {
            System.out.print(">");
        } else {
            System.out.print(" ");
            for (int index = 0; index < attributes.getLength(); index++) {
                System.out.print(attributes.getLocalName(index) + " => "
                        + attributes.getValue(index));
            }
            System.out.print(">");
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        System.out.print("\n</" + qName + ">");
    }
}

输出为：

<scxml version => 1.0initialstate => startname => calc>
<datamodel>
<data id => exprexpr => 0>
</data>
<data id => resexpr => 0>
</data>
</datamodel>
<state id => start>
<transition event => OPERtarget => opEntered>
</transition>
<transition event => DIGITtarget => operand>
</transition>
</state>
<state id => operand>
<transition event => OPERtarget => opEntered>
</transition>
<transition event => DIGIT>
</transition>
</state>
</scxml>

这篇关于无法使用SAX读取某些属性的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！