1. 首页
  2. JavaAPI

Java javax.xml.bind.helpers Class AbstractUnmarshallerImpl（JDK8）

158 阅读 0 评论

Skip navigation links
Java™ Platform
Standard Ed. 8
javax.xml.bind.helpers

Class AbstractUnmarshallerImpl

  • All Implemented Interfaces:
    Unmarshaller 

    public abstract class AbstractUnmarshallerImpl
extends Object
implements Unmarshaller
    Partial default Unmarshaller implementation.

    This class provides a partial default implementation for the Unmarshallerinterface.

    A JAXB Provider has to implement five methods (getUnmarshallerHandler, unmarshal(Node), unmarshal(XMLReader,InputSource), unmarshal(XMLStreamReader), and unmarshal(XMLEventReader).

    Since:
    JAXB1.0
    See Also:
    Unmarshaller

    • Field Detail

      • validating

        protected boolean validating
        whether or not the unmarshaller will validate

    • Constructor Detail

      • AbstractUnmarshallerImpl

        public AbstractUnmarshallerImpl()

    • Method Detail

      • getXMLReader

        protected XMLReader getXMLReader()
                          throws JAXBException
        Obtains a configured XMLReader. This method is used when the client-specified SAXSource object doesn't have XMLReader. Unmarshaller is not re-entrant, so we will only use one instance of XMLReader.
        Throws:
        JAXBException

      • unmarshal

        public Object unmarshal(Source source)
                 throws JAXBException
        Description copied from interface: Unmarshaller
        Unmarshal XML data from the specified XML Source and return the resulting content tree.

        Implements Unmarshal Global Root Element.

        SAX 2.0 Parser Pluggability

        A client application can choose not to use the default parser mechanism supplied with their JAXB provider. Any SAX 2.0 compliant parser can be substituted for the JAXB provider's default mechanism. To do so, the client application must properly configure a SAXSource containing an XMLReader implemented by the SAX 2.0 parser provider. If the XMLReader has an org.xml.sax.ErrorHandler registered on it, it will be replaced by the JAXB Provider so that validation errors can be reported via the ValidationEventHandler mechanism of JAXB. If the SAXSource does not contain an XMLReader, then the JAXB provider's default parser mechanism will be used.

        This parser replacement mechanism can also be used to replace the JAXB provider's unmarshal-time validation engine. The client application must properly configure their SAX 2.0 compliant parser to perform validation (as shown in the example above). Any SAXParserExceptions encountered by the parser during the unmarshal operation will be processed by the JAXB provider and converted into JAXB ValidationEvent objects which will be reported back to the client via the ValidationEventHandler registered with the Unmarshaller. Note: specifying a substitute validating SAX 2.0 parser for unmarshalling does not necessarily replace the validation engine used by the JAXB provider for performing on-demand validation.

        The only way for a client application to specify an alternate parser mechanism to be used during unmarshal is via the unmarshal(SAXSource) API. All other forms of the unmarshal method (File, URL, Node, etc) will use the JAXB provider's default parser and validator mechanisms.

        Specified by:
        unmarshal in interface Unmarshaller
        Parameters:
        source - the XML Source to unmarshal XML data from (providers are only required to support SAXSource, DOMSource, and StreamSource)
        Returns:
        the newly created root object of the java content tree
        Throws:
        JAXBException - If any unexpected errors occur while unmarshalling
        UnmarshalException - If the ValidationEventHandler returns false from its handleEvent method or the Unmarshaller is unable to perform the XML to Java binding. See Unmarshalling XML Data
        See Also:
        Unmarshaller.unmarshal(javax.xml.transform.Source, Class)

      • unmarshal

        protected abstract Object unmarshal(XMLReader reader,
                                    InputSource source)
                             throws JAXBException
        Unmarshals an object by using the specified XMLReader and the InputSource. The callee should call the setErrorHandler method of the XMLReader so that errors are passed to the client-specified ValidationEventHandler.
        Throws:
        JAXBException

      • unmarshal

        public final Object unmarshal(Reader reader)
                       throws JAXBException
        Description copied from interface: Unmarshaller
        Unmarshal XML data from the specified Reader and return the resulting content tree. Validation event location information may be incomplete when using this form of the unmarshal API, because a Reader does not provide the system ID.

        Implements Unmarshal Global Root Element.

        Specified by:
        unmarshal in interface Unmarshaller
        Parameters:
        reader - the Reader to unmarshal XML data from
        Returns:
        the newly created root object of the java content tree
        Throws:
        JAXBException - If any unexpected errors occur while unmarshalling
        UnmarshalException - If the ValidationEventHandler returns false from its handleEvent method or the Unmarshaller is unable to perform the XML to Java binding. See Unmarshalling XML Data

      • isValidating

        public boolean isValidating()
                     throws JAXBException
        Indicates whether or not the Unmarshaller is configured to validate during unmarshal operations.

        Note: I named this method isValidating() to stay in-line with JAXP, as opposed to naming it getValidating().

        Specified by:
        isValidating in interface Unmarshaller
        Returns:
        true if the Unmarshaller is configured to validate during unmarshal operations, false otherwise
        Throws:
        JAXBException - if an error occurs while retrieving the validating flag

      • setEventHandler

        public void setEventHandler(ValidationEventHandler handler)
                     throws JAXBException
        Allow an application to register a validation event handler.

        The validation event handler will be called by the JAXB Provider if any validation errors are encountered during calls to any of the unmarshal methods. If the client application does not register a validation event handler before invoking the unmarshal methods, then all validation events will be silently ignored and may result in unexpected behaviour.

        Specified by:
        setEventHandler in interface Unmarshaller
        Parameters:
        handler - the validation event handler
        Throws:
        JAXBException - if an error was encountered while setting the event handler

      • setValidating

        public void setValidating(boolean validating)
                   throws JAXBException
        Specifies whether or not the Unmarshaller should validate during unmarshal operations. By default, the Unmarshaller does not validate.

        This method may only be invoked before or after calling one of the unmarshal methods.

        Specified by:
        setValidating in interface Unmarshaller
        Parameters:
        validating - true if the Unmarshaller should validate during unmarshal, false otherwise
        Throws:
        JAXBException - if an error occurred while enabling or disabling validation at unmarshal time

      • getEventHandler

        public ValidationEventHandler getEventHandler()
                                       throws JAXBException
        Return the current event handler or the default event handler if one hasn't been set.
        Specified by:
        getEventHandler in interface Unmarshaller
        Returns:
        the current ValidationEventHandler or the default event handler if it hasn't been set
        Throws:
        JAXBException - if an error was encountered while getting the current event handler

      • createUnmarshalException

        protected UnmarshalException createUnmarshalException(SAXException e)
        Creates an UnmarshalException from a SAXException. This is an utility method provided for the derived classes.

        When a provider-implemented ContentHandler wants to throw a JAXBException, it needs to wrap the exception by a SAXException. If the unmarshaller implementation blindly wrap SAXException by JAXBException, such an exception will be a JAXBException wrapped by a SAXException wrapped by another JAXBException. This is silly.

        This method checks the nested exception of SAXException and reduce those excessive wrapping.

        Returns:
        the resulting UnmarshalException

      • setProperty

        public void setProperty(String name,
                        Object value)
                 throws PropertyException
        Default implementation of the setProperty method always throws PropertyException since there are no required properties. If a provider needs to handle additional properties, it should override this method in a derived class.
        Specified by:
        setProperty in interface Unmarshaller
        Parameters:
        name - the name of the property to be set. This value can either be specified using one of the constant fields or a user supplied string.
        value - the value of the property to be set
        Throws:
        PropertyException - when there is an error processing the given property or value

      • getProperty

        public Object getProperty(String name)
                   throws PropertyException
        Default implementation of the getProperty method always throws PropertyException since there are no required properties. If a provider needs to handle additional properties, it should override this method in a derived class.
        Specified by:
        getProperty in interface Unmarshaller
        Parameters:
        name - the name of the property to retrieve
        Returns:
        the value of the requested property
        Throws:
        PropertyException - when there is an error retrieving the given property or value property name

      • unmarshal

        public <T> JAXBElement<T> unmarshal(XMLStreamReader reader,
                                    Class<T> expectedType)
                             throws JAXBException
        Description copied from interface: Unmarshaller
        Unmarshal root element to JAXB mapped declaredType and return the resulting content tree.

        This method implements unmarshal by declaredType.

        This method assumes that the parser is on a START_DOCUMENT or START_ELEMENT event. Unmarshalling will be done from this start event to the corresponding end event. If this method returns successfully, the reader will be pointing at the token right after the end event.

        Specified by:
        unmarshal in interface Unmarshaller
        Parameters:
        reader - The parser to be read.
        expectedType - appropriate JAXB mapped class to hold reader's START_ELEMENT XML data.
        Returns:
        content tree rooted by JAXB Element representation
        Throws:
        JAXBException - If any unexpected errors occur while unmarshalling
        UnmarshalException - If the ValidationEventHandler returns false from its handleEvent method or the Unmarshaller is unable to perform the XML to Java binding. See Unmarshalling XML Data

      • unmarshal

        public <T> JAXBElement<T> unmarshal(XMLEventReader reader,
                                    Class<T> expectedType)
                             throws JAXBException
        Description copied from interface: Unmarshaller
        Unmarshal root element to JAXB mapped declaredType and return the resulting content tree.

        This method implements unmarshal by declaredType.

        This method assumes that the parser is on a START_DOCUMENT or START_ELEMENT event. Unmarshalling will be done from this start event to the corresponding end event. If this method returns successfully, the reader will be pointing at the token right after the end event.

        Specified by:
        unmarshal in interface Unmarshaller
        Parameters:
        reader - The parser to be read.
        expectedType - appropriate JAXB mapped class to hold reader's START_ELEMENT XML data.
        Returns:
        content tree rooted by JAXB Element representation
        Throws:
        JAXBException - If any unexpected errors occur while unmarshalling
        UnmarshalException - If the ValidationEventHandler returns false from its handleEvent method or the Unmarshaller is unable to perform the XML to Java binding. See Unmarshalling XML Data

      • setSchema

        public void setSchema(Schema schema)
        Description copied from interface: Unmarshaller
        Specify the JAXP 1.3 Schema object that should be used to validate subsequent unmarshal operations against. Passing null into this method will disable validation.

        This method replaces the deprecated setValidating(boolean) API.

        Initially this property is set to null.

        Specified by:
        setSchema in interface Unmarshaller
        Parameters:
        schema - Schema object to validate unmarshal operations against or null to disable validation

      • getSchema

        public Schema getSchema()
        Description copied from interface: Unmarshaller
        Get the JAXP 1.3 Schema object being used to perform unmarshal-time validation. If there is no Schema set on the unmarshaller, then this method will return null indicating that unmarshal-time validation will not be performed.

        This method provides replacement functionality for the deprecated Unmarshaller.isValidating() API as well as access to the Schema object. To determine if the Unmarshaller has validation enabled, simply test the return type for null:

        boolean isValidating = u.getSchema()!=null;

        Specified by:
        getSchema in interface Unmarshaller
        Returns:
        the Schema object being used to perform unmarshal-time validation or null if not present

      • setAdapter

        public <A extends XmlAdapter> void setAdapter(Class<A> type,
                                              A adapter)
        Description copied from interface: Unmarshaller
        Associates a configured instance of XmlAdapter with this unmarshaller.

        Every unmarshaller internally maintains a Map<Class,XmlAdapter>, which it uses for unmarshalling classes whose fields/methods are annotated with XmlJavaTypeAdapter.

        This method allows applications to use a configured instance of XmlAdapter. When an instance of an adapter is not given, an unmarshaller will create one by invoking its default constructor.

        Specified by:
        setAdapter in interface Unmarshaller
        Parameters:
        type - The type of the adapter. The specified instance will be used when XmlJavaTypeAdapter.value() refers to this type.
        adapter - The instance of the adapter to be used. If null, it will un-register the current adapter set for this type.
Skip navigation links
Java™ Platform
Standard Ed. 8

Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2022, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.

微信小程序

微信扫一扫体验

微信公众账号

微信扫一扫加关注

 发表
评论 返回
顶部