如何使用Java和带有include的XSD验证XML文件？

Z时代
2024-01-10
分类：问答

我正在使用Java 5 javax.xml.validation.Validator来验证XML文件。我已经完成了一个仅使用导入的架构，并且一切正常。现在，我尝试使用另一种使用导入和包含的模式进行验证。我的问题是主模式中的元素被忽略，验证表明无法找到它们的声明。

这是我构建模式的方法：

InputStream includeInputStream = getClass().getClassLoader().getResource("include.xsd").openStream();
InputStream importInputStream = getClass().getClassLoader().getResource("import.xsd").openStream();
InputStream mainInputStream = getClass().getClassLoader().getResource("main.xsd").openStream();
Source[] sourceSchema = new SAXSource[]{includeInputStream , importInputStream, 
mainInputStream };
Schema schema = factory.newSchema(sourceSchema);

现在这是main.xsd中声明的摘录

<xsd:schema xmlns="http://schema.omg.org/spec/BPMN/2.0" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:import="http://www.foo.com/import" targetNamespace="http://main/namespace" elementFormDefault="qualified" attributeFormDefault="unqualified">
    <xsd:import namespace="http://www.foo.com/import" schemaLocation="import.xsd"/>
    <xsd:include schemaLocation="include.xsd"/>
    <xsd:element name="element" type="tElement"/>
    <...>
</xsd:schema>

如果我将包含的XSD的代码复制到main.xsd中，则可以正常工作。如果我不这样做，验证将找不到“元素”的声明。

回答：

您需要使用LSResourceResolver才能正常工作。请查看下面的示例代码。

验证方法：

// note that if your XML already declares the XSD to which it has to conform, then there's no need to declare the schemaName here
void validate(String xml, String schemaName) throws Exception {
    DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
    builderFactory.setNamespaceAware(true);
    DocumentBuilder parser = builderFactory
            .newDocumentBuilder();
    // parse the XML into a document object
    Document document = parser.parse(new StringInputStream(xml));
    SchemaFactory factory = SchemaFactory
            .newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
    // associate the schema factory with the resource resolver, which is responsible for resolving the imported XSD's
    factory.setResourceResolver(new ResourceResolver());
            // note that if your XML already declares the XSD to which it has to conform, then there's no need to create a validator from a Schema object
    Source schemaFile = new StreamSource(getClass().getClassLoader()
            .getResourceAsStream(schemaName));
    Schema schema = factory.newSchema(schemaFile);
    Validator validator = schema.newValidator();
    validator.validate(new DOMSource(document));
}

资源解析器实现：

public class ResourceResolver  implements LSResourceResolver {
public LSInput resolveResource(String type, String namespaceURI,
        String publicId, String systemId, String baseURI) {
     // note: in this sample, the XSD's are expected to be in the root of the classpath
    InputStream resourceAsStream = this.getClass().getClassLoader()
            .getResourceAsStream(systemId);
    return new Input(publicId, systemId, resourceAsStream);
}
 }

资源解析器返回的Input实现：

public class Input implements LSInput {
private String publicId;
private String systemId;
public String getPublicId() {
    return publicId;
}
public void setPublicId(String publicId) {
    this.publicId = publicId;
}
public String getBaseURI() {
    return null;
}
public InputStream getByteStream() {
    return null;
}
public boolean getCertifiedText() {
    return false;
}
public Reader getCharacterStream() {
    return null;
}
public String getEncoding() {
    return null;
}
public String getStringData() {
    synchronized (inputStream) {
        try {
            byte[] input = new byte[inputStream.available()];
            inputStream.read(input);
            String contents = new String(input);
            return contents;
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("Exception " + e);
            return null;
        }
    }
}
public void setBaseURI(String baseURI) {
}
public void setByteStream(InputStream byteStream) {
}
public void setCertifiedText(boolean certifiedText) {
}
public void setCharacterStream(Reader characterStream) {
}
public void setEncoding(String encoding) {
}
public void setStringData(String stringData) {
}
public String getSystemId() {
    return systemId;
}
public void setSystemId(String systemId) {
    this.systemId = systemId;
}
public BufferedInputStream getInputStream() {
    return inputStream;
}
public void setInputStream(BufferedInputStream inputStream) {
    this.inputStream = inputStream;
}
private BufferedInputStream inputStream;
public Input(String publicId, String sysId, InputStream input) {
    this.publicId = publicId;
    this.systemId = sysId;
    this.inputStream = new BufferedInputStream(input);
}
}