Package com.sun.xml.bind.api

Class ClassResolver

java.lang.Object
com.sun.xml.bind.api.ClassResolver
public abstract class ClassResolver extends 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 Details

    • ClassResolver

      public ClassResolver()

  • Method Details

    • resolveElementName

      @Nullable public abstract Class<?> resolveElementName(@NotNull String nsUri, @NotNull String localName) throws 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:
      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.)