JAXB学习 （三）验证
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller(); unmarshaller.setSchema(SchemaFactory.newInstance( XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema( new File("students.xsd")));

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从jaxb2.0开始，通过调用方法setSchema()的方式来指定验证，在2.0以前的版本里，通过调用setValidating()方法来指定验证：unmarshaller.setValidating( Unmarshaller unmarshaller = jaxbContext.createUnmarshaller(); unmarshaller.setSchema(SchemaFactory.newInstance( XMLConstants.RELAXNG_NS_URI).newSchema( new File("students.dtd")));

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一旦设置了验证信息，在进行unmarshell的时候，jaxb就会对读入的xml文件进行验证，例如有schema文件

<?xml version="1.0" encoding="UTF-8"?><schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:tns="http://www.liulutu.com/students/"    targetNamespace="http://www.liulutu.com/students/">    <element name="students">        <complexType>            <sequence>                <element name="student" type="tns:StudentType" maxOccurs="unbounded" />            </sequence>        </complexType>    </element>    <simpleType name="SexType">        <restriction base="string">            <enumeration value="Male"></enumeration>            <enumeration value="Female"></enumeration>        </restriction>    </simpleType>    <complexType name="StudentType">        <attribute name="sex" type="tns:SexType"></attribute>        <attribute name="name" type="string"></attribute>    </complexType></schema>

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和符合这个schema的一个xml文件：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><ns2:students xmlns:ns2="http://www.liulutu.com/students/"></ns2:students>

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如果指定了需要验证，当根据上面的schema读入些xml时，就会抛出一个验证失败

异常：

[org.xml.sax.SAXParseException: cvc-complex-type.2.4.b: The content of element 'ns2:students' is not complete. One of '{student}' is expected.]    at javax.xml.bind.helpers.AbstractUnmarshallerImpl.createUnmarshalException(Unknown Source)    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.createUnmarshalException(Unknown Source)    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(Unknown Source)    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(Unknown Source)    at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)    at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)    at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)    at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)

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注：需要在unmarshall.unmarshall()方法调用之前设置验证信息。

jaxb2.0中，marshall和unmarshall的验证设置是一样的：

??? ???

ObjectFactory factory = new ObjectFactory();        Students students = factory.createStudents();        Marshaller marshaller = jaxbContext.createMarshaller();        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);        marshaller.setSchema(SchemaFactory.newInstance(                XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(                new File("students.xsd")));        marshaller.marshal(students, new File("a.xml"));

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和上面一样，会得到一个异常信息：

[org.xml.sax.SAXParseException: cvc-complex-type.2.4.b: The content of element 'ns2:students' is not complete. One of '{student}' is expected.]    at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.write(Unknown Source)    at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.marshal(Unknown Source)    at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(Unknown Source)

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如果使用jaxb2.0之前的版本，则验证方式如下：

??? ??? Validator validator = jaxbContext.createValidator();
??? ??? validator.validate(students);

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