javajaxb检查xml对于声明的xsd是否有效

Question

在调用解组器的解组方法之前，我需要知道xml是否有效

现在我这样做：

JAXBContext jaxbContext = JAXBContext.newInstance("package");

final Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
final SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
final File xsdFile = new File("pathtoxsd/file.xsd");
final Schema schema = schemaFactory.newSchema(xsdFile);

unmarshaller.setSchema(schema);
unmarshaller.setEventHandler(new ValidationEventHandler() {
    @Override
    public boolean handleEvent(ValidationEvent arg0)
    {
            return false;
    }
});

final File xmlFile = new File("pathtoxml/fileName.xml");

final Object unmarshalled = unmarshaller.unmarshal(xmlFile);

但我不想被迫知道xsd在哪里。xsd路径应仅由其内部的xml声明，封送拆收器应遵循xml声明的路径

Answer 1

您可以执行以下操作：

1. 使用StAX解析器解析XML文档
2. 前进到根元素
3. 抓取schemaLocation属性（您可能还需要处理noNamespaceSchemaLocation属性）
4. 从该值中获取XSD的路径（空格后面的部分）
5. 基于该值创建Schema
6. 在Unmarshaller上设置Schema

import javax.xml.XMLConstants;
import javax.xml.bind.*;
import javax.xml.stream.*;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        XMLInputFactory xif = XMLInputFactory.newFactory();
        StreamSource xml = new StreamSource("src/forum21317146/input.xml");
        XMLStreamReader xsr = xif.createXMLStreamReader(xml);
        xsr.next();

        JAXBContext jc = JAXBContext.newInstance(Foo.class);
        Unmarshaller unmarshaller = jc.createUnmarshaller();

        String schemaLocation = xsr.getAttributeValue(XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI, "schemaLocation");
        if(null != schemaLocation) {
            String xsd = schemaLocation.substring(schemaLocation.lastIndexOf(' ') + 1);
            SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
            Schema schema = schemaFactory.newSchema(new StreamSource(xsd));
            unmarshaller.setSchema(schema);
        }

        unmarshaller.unmarshal(xsr);

    }

}