使用Java进行条件XML解析

Question

我正在寻找一个合适的解析器来解析给定的XML。我想解析整个XML只有当标签- 'employee'，属性- 'validated=false'否则停止解析。如何使用SAX、STAX或任何其他解析器执行条件XML解析?

<?xml version="1.0"?>
<database>
<employee validated="False">
  <name>Lars </name>
  <street validated="False"> Test </street>
  <telephone number= "0123"/>
</employee>  
<employee validated="True">
  <name>Baegs </name>
  <street validated="True"> Test </street>
  <telephone number= "0123"/>
</employee>  
</database>

我尝试了下面的SAX解析器代码

    List<XmlObjects> xmlObjects;
    String espXmlFileName;
    String tmpValue;
    XmlObjects xmlObjectsTmp;
    public SaxParser(String espXmlFileName) {
        this.espXmlFileName = espXmlFileName;
        xmlObjects = new ArrayList<XmlObjects>();
        parseDocument();
        printDatas();
    }
    private void printDatas() {
        for (XmlObjects tmpB : xmlObjects) {
            System.out.println(tmpB.toString());
        }
    }
    private void parseDocument() {
        SAXParserFactory factory = SAXParserFactory.newInstance();
        try {
            SAXParser parser = factory.newSAXParser();
            parser.parse(espXmlFileName, this);
        } catch (ParserConfigurationException e) {
            System.out.println("ParserConfig error");
        } catch (SAXException e) {
            System.out.println("SAXException : xml not well formed");
        } catch (IOException e) {
            System.out.println("IO error");
        }
    }

public void startElement(String uri, String localName, String qName,
            org.xml.sax.Attributes attributes) throws SAXException {
        if (qName.equalsIgnoreCase("employee")) {
            String value1 = attributes.getValue("validated");
            if (value1.equalsIgnoreCase("FALSE")) {
                if (qName.equalsIgnoreCase("name")) {
                    String value2 = attributes.getValue("validated");
                        xmlObjectsTmp.setName(attributes
                                            .getValue("name"));
                                }
                            }

    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        if (qName.equalsIgnoreCase("employee")) {
            xmlObjects.add(xmlObjectsTmp);
        }
        if (qName.equalsIgnoreCase("name")) {
            xmlObjectsTmp.setName(tmpValue);
        }

    }
    public static void main(String argv[]) {
        new SaxParser("C:\xml\xml2.xml");
    }

Answer 1

在ContentHandler的startElement方法中，当您的validated属性具有值True时，您可以简单地抛出SAXException以中止解析。

例如:

@Override
public void startElement(final String uri, final String localName,
    final String qName, final Attributes attributes) throws SAXException {
    if(localName.equalsIgnoreCase("employee") || localName.equalsIgnoreCase("street")) {
        final String validated = attributes.getValue("validated");
        if(validated != null && !validated.equals("False")) {
            throw new SAXException(localName + " has already been validated");
        } else {
            //your processing logic here
        }
    }
}

如果你愿意，你可以注册一个ErrorHandler来用你自己的方式处理这个错误。