Class ClassResolver


  • public abstract class ClassResolver
    extends java.lang.Object
    Dynamically locates classes to represent elements discovered during the unmarshalling.

    THIS INTERFACE IS SUBJECT TO CHANGE WITHOUT NOTICE.

    Background

    JAXBContext.newInstance(Class...) requires that application informs JAXB about all the classes that it may see in the instance document. While this allows JAXB to take time to optimize the unmarshalling, it is sometimes inconvenient for applications.

    This is where ClassResolver comes to resucue.

    A ClassResolver instance can be specified on Unmarshaller via Unmarshaller.setProperty(String, Object) as follows:

     unmarshaller.setProperty( ClassResolver.class.getName(), new MyClassResolverImpl() );
     

    When an Unmarshaller encounters (i) an unknown root element or (ii) unknown elements where unmarshaller is trying to unmarshal into XmlAnyElement with lax=true, unmarshaller calls resolveElementName(String, String) method to see if the application may be able to supply a class that corresponds to that class.

    When a Class is returned, a new JAXBContext is created with all the classes known to it so far, plus a new class returned. This operation may fail (for example because of some conflicting annotations.) This failure is handled just like Exceptions thrown from resolveElementName(String, String).

    Since:
    2.1
    Author:
    Kohsuke Kawaguchi
    • Constructor Summary

      Constructors 
      Constructor Description
      ClassResolver()  
    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      abstract java.lang.Class<?> resolveElementName​(java.lang.String nsUri, java.lang.String localName)
      JAXB calls this method when it sees an unknown element.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • ClassResolver

        public ClassResolver()
    • Method Detail

      • resolveElementName

        @Nullable
        public abstract java.lang.Class<?> resolveElementName​(@NotNull
                                                              java.lang.String nsUri,
                                                              @NotNull
                                                              java.lang.String localName)
                                                       throws java.lang.Exception
        JAXB calls this method when it sees an unknown element.

        See the class javadoc for details.

        Parameters:
        nsUri - Namespace URI of the unknown element. Can be empty but never null.
        localName - Local name of the unknown element. Never be empty nor null.
        Returns:
        If a non-null class is returned, it will be used to unmarshal this element. If null is returned, the resolution is assumed to be failed, and the unmarshaller will behave as if there was no ClassResolver to begin with (that is, to report it to ValidationEventHandler, then move on.)
        Throws:
        java.lang.Exception - Throwing any RuntimeException causes the unmarshaller to stop immediately. The exception will be propagated up the call stack. Throwing any other checked Exception results in the error reproted to ValidationEventHandler (just like any other error during the unmarshalling.)