JAXB 模式验证
了解根据架构(xsd)验证 XML,然后将 XML 解组到 Java 对象。 如果验证失败,还请学习在 xml 模式验证期间检查验证错误。
阅读更多:如何从 JAXB 类生成模式
1.在 XSD 验证后将 XML 转换为 Java 对象
我们已经看到了将 XML 文件读取到 Java 对象的示例。 现在让我们修改该示例,以在填充Employee
对象之前针对 XSD 验证 XML。
package com.howtodoinjava.demo;
import java.io.File;
import javax.xml.XMLConstants;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import org.xml.sax.SAXException;
import com.howtodoinjava.demo.model.Employee;
public class JaxbExample
{
public static void main(String[] args)
{
String xmlFile = "employee.xml";
String xsdFile = "employee.xsd";
jaxbXmlFileToObject(xmlFile, xsdFile);
}
private static void jaxbXmlFileToObject(String xmlFile, String xsdFile) {
JAXBContext jaxbContext;
try
{
//Get JAXBContext
jaxbContext = JAXBContext.newInstance(Employee.class);
//Create Unmarshaller
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
//Setup schema validator
SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema employeeSchema = sf.newSchema(new File(xsdFile));
jaxbUnmarshaller.setSchema(employeeSchema);
//Unmarshal xml file
Employee employee = (Employee) jaxbUnmarshaller.unmarshal(new File(xmlFile));
System.out.println(employee);
}
catch (JAXBException | SAXException e)
{
e.printStackTrace();
}
}
}
程序输出。
Employee [id=1, firstName=Lokesh, lastName=Gupta, department=Department [id=101, name=IT]]
下面给出employee.xml
和employee.xsd
的含量。
<employees>
<employee id="101">
<name>Lokesh Gupta</name>
<title>Author</title>
</employee>
<employee id="102">
<name>Brian Lara</name>
<title>Cricketer</title>
</employee>
</employees>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<xs:schema version="1.0" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="department" type="department"/>
<xs:element name="employee" type="employee"/>
<xs:complexType name="employee">
<xs:sequence>
<xs:element ref="department" minOccurs="0"/>
<xs:element name="firstName" type="xs:string" minOccurs="0"/>
<xs:element name="id" type="xs:int" minOccurs="0"/>
<xs:element name="lastName" type="xs:string" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="department">
<xs:sequence>
<xs:element name="id" type="xs:int" minOccurs="0"/>
<xs:element name="name" type="xs:string" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
</xs:schema>
2.模式验证错误
针对 XML 的 XSD 验证不会总是成功。 很多时候,您会收到验证错误。 这些错误将作为SAXException
抛出。 因此捕获此异常,它将具有验证失败的上下文。
例如,我已通过此更改更新了架构文件。
<xs:element name="firstName" type="xs:string" minOccurs="0"/>
//to
<xs:element name="firstName" type="xs:int" minOccurs="0"/>
现在来看验证错误。
javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException; systemId: file:/C:/Users/lokesh/workspace/App/employee.xml; lineNumber: 7; columnNumber: 34;
cvc-datatype-valid.1.2.1: 'Lokesh' is not a valid value for 'integer'.]
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.createUnmarshalException(AbstractUnmarshallerImpl.java:335)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.createUnmarshalException(UnmarshallerImpl.java:563)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:249)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:214)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:157)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:162)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:171)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:189)
at com.howtodoinjava.demo.JaxbExample.jaxbXmlFileToObject(JaxbExample.java:45)
at com.howtodoinjava.demo.JaxbExample.main(JaxbExample.java:23)
Caused by: org.xml.sax.SAXParseException; systemId: file:/C:/Users/lokesh/workspace/App/employee.xml; lineNumber: 7; columnNumber: 34;
cvc-datatype-valid.1.2.1: 'Lokesh' is not a valid value for 'integer'.
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:203)
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:134)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:437)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:368)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:325)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator$XSIErrorReporter.reportError(XMLSchemaValidator.java:458)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.reportSchemaError(XMLSchemaValidator.java:3237)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.elementLocallyValidType(XMLSchemaValidator.java:3152)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.processElementContent(XMLSchemaValidator.java:3062)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.handleEndElement(XMLSchemaValidator.java:2140)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.endElement(XMLSchemaValidator.java:859)
at com.sun.org.apache.xerces.internal.jaxp.validation.ValidatorHandlerImpl.endElement(ValidatorHandlerImpl.java:584)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.ValidatingUnmarshaller.endElement(ValidatingUnmarshaller.java:91)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.SAXConnector.endElement(SAXConnector.java:165)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:609)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1782)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2973)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:117)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1213)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:649)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:243)
... 7 more
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