XSD验证中的SaxParseException不提供元素名称

Question

我有一个xsd文件和一个xml文件,我正在使用以下代码对xsd文件验证xml文件

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setValidating(true);
        factory.setAttribute(
                "http://java.sun.com/xml/jaxp/properties/schemaLanguage",
                "http://www.w3.org/2001/XMLSchema");
        factory.setAttribute(
                "http://java.sun.com/xml/jaxp/properties/schemaSource",
                new InputSource(new StringReader(xsd)));
        Document doc = null;
        try {
            DocumentBuilder parser = factory.newDocumentBuilder();
            MyErrorHandler errorHandler = new MyErrorHandler();
            parser.setErrorHandler(errorHandler);
            doc = parser.parse(new InputSource(new StringReader(xml))); 
            return true;
        } catch (ParserConfigurationException e) {
            System.out.println("Parser not configured: " + e.getMessage());
        } catch (SAXException e) {
            System.out.print("Parsing XML failed due to a "
                    + e.getClass().getName() + ":");
            System.out.println(e.getMessage());
        } catch (IOException e) {
            System.out.println("IOException thrown");
            e.printStackTrace();
        }
        return false;

MyErrorHanlder是

private static class MyErrorHandler implements ErrorHandler {
        public void warning(SAXParseException spe) throws SAXException {
            System.out.println("Warning: " + spe.getMessage() + " getColumnNumber is " + spe.getColumnNumber() + " getLineNumber " + spe.getLineNumber() + " getPublicId " + spe.getPublicId() + " getSystemId " + spe.getSystemId());
        }

        public void error(SAXParseException spe) throws SAXException {
            System.out.println("Error: " + spe.getMessage() + " getColumnNumber is " + spe.getColumnNumber() + " getLineNumber " + spe.getLineNumber() + " getPublicId " + spe.getPublicId() + " getSystemId " + spe.getSystemId());
            throw new SAXException("Error: " + spe.getMessage());
        }

        public void fatalError(SAXParseException spe) throws SAXException {
            System.out.println("Fatal Error:  " + spe.getMessage() + " getColumnNumber is " + spe.getColumnNumber() + " getLineNumber " + spe.getLineNumber() + " getPublicId " + spe.getPublicId() + " getSystemId " + spe.getSystemId());
            throw new SAXException("Fatal Error: " + spe.getMessage());
        }
    }

当xml不符合xsd我得到一个异常..但是这个异常没有xsd元素的名称,因为这个错误发生了..消息看起来像

由于org.xml.sax.SAXException,解析XML失败:错误:cvc-minLength-valid:对于类型为"null"的minLength'1',值''with length ='0'不是facet-valid.

而不是打印xsd元素的名称,错误消息只有''.因此,我无法找到并向用户显示导致错误的确切元素.

我的xsd元素看起来像这样

<xs:element name="FullName_FirstName">
    <xs:annotation>
        <xs:appinfo>
            <ie:label>First Name</ie:label>
            <ie:html_element>0</ie:html_element>
        </xs:appinfo>
    </xs:annotation>
    <xs:simpleType>
        <xs:restriction base="xs:string">
            <xs:minLength value="1"/>
        </xs:restriction>
    </xs:simpleType>
</xs:element>

提前致谢

Answer 1

首先,一些建议.您不需要构建DOM文档来进行验证.这会导致大量内存开销,甚至可能耗尽大型输入XML文档.你可以使用一个SAXParser.如果您使用的是Java 1.5或更高版本,则甚至不需要.从该版本开始,Java SE中包含了一个XML验证API.检查包javax.xml.validation以获取更多信息.我们的想法是,您首先构建一个Schema对象,然后Validator从可用于进行验证的对象中获取一个对象.它接受任何Source输入实现.也可以给出验证器ErrorHandlers,因此您可以重复使用您的类.当然,实际上你可能需要一个DOM,但在这种情况下,最好还是创建一个Schema实例并将其注册到你的实例中DocumentBuilderFactory.

现在,针对实际问题.这并不容易,因为SAXParseException它没有为您提供太多的上下文信息.最好的办法是在ContentHandler某个地方连接并跟踪你所在的元素或其他位置信息.然后,您可以在需要时将其赋予错误处理程序.该类DefaultHandler或是DefaultHandler2将错误和内容处理相结合的便捷方式.您可以在org.xml.sax.ext包中找到这些类.

我已经在下面发布了一个测试.现在,我确实获得了两行输出而不是预期输出.如果这是因为我正在使用Schema,或者因为我没有抛出异常并继续处理,我不确定.第二行确实包含元素的名称,因此可能就足够了.您可以在错误上设置一些标志,而不是抛出异常并结束解析.

package jaxb.test;

import java.io.StringReader;
import javax.xml.XMLConstants;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.Source;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;

public class ValidationTest {

    public static void main(String[] args) throws Exception {

        //Test XML and schema
        final String xml = "<?xml version=\"1.0\"?><test><test2></test2></test>";
        final String schemaString =
            "<?xml version=\"1.0\"?>"
            + "<xsd:schema xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" elementFormDefault=\"unqualified\" attributeFormDefault=\"unqualified\">"
            + "<xsd:element name=\"test\" type=\"Test\"/>"
            + "<xsd:element name=\"test2\" type=\"Test2\"/>"
            + "<xsd:complexType name=\"Test\">"
            + "<xsd:sequence>"
            + "<xsd:element ref=\"test2\" minOccurs=\"1\" maxOccurs=\"unbounded\"/>"
            + "</xsd:sequence>"
            + "</xsd:complexType>"
            + "<xsd:simpleType name=\"Test2\">"
            + "<xsd:restriction base=\"xsd:string\"><xsd:minLength value=\"1\"/></xsd:restriction>"
            + "</xsd:simpleType>"
            + "</xsd:schema>";

        //Building a Schema instance
        final Source schemaSource =
            new StreamSource(new StringReader(schemaString));
        final Schema schema =
            SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(schemaSource);

        //Creating a SAXParser for our input XML
        //First the factory
        final SAXParserFactory factory = SAXParserFactory.newInstance();
        //Must be namespace aware to receive element names
        factory.setNamespaceAware(true);
        //Setting the Schema for validation
        factory.setSchema(schema);
        //Now the parser itself
        final SAXParser parser = factory.newSAXParser();

        //Creating an instance of our special handler
        final MyContentHandler handler = new MyContentHandler();

        //Parsing
        parser.parse(new InputSource(new StringReader(xml)), handler);

    }

    private static class MyContentHandler extends DefaultHandler {

        private String element = "";

        @Override
        public void startElement(String uri, String localName, String qName,
                Attributes attributes) throws SAXException {

            if(localName != null && !localName.isEmpty())
                element = localName;
            else
                element = qName;

        }

        @Override
        public void warning(SAXParseException exception) throws SAXException {
            System.out.println(element + ": " + exception.getMessage());
        }

        @Override
        public void error(SAXParseException exception) throws SAXException {
            System.out.println(element + ": " + exception.getMessage());
        }

        @Override
        public void fatalError(SAXParseException exception) throws SAXException {
            System.out.println(element + ": " + exception.getMessage());
        }

        public String getElement() {
            return element;
        }

    }

}

这有点粗糙,但你可以从中做到这一点,以获得你需要的东西.