* As noted in the return value portion of the javadoc, there * are several cases where the preference cannot be honored. * Specifically, as of JAXB RI 2.0 and onward: * *
* By default, the JAXB RI 1.0.x produces namespace declarations only when * they are necessary, only at where they are used. Because of this * lack of look-ahead, sometimes the marshaller produces a lot of * namespace declarations that look redundant to human eyes. For example, *
{@code
*
*
* ...
* ...
* ...
* ...
*
* }
*
* * The JAXB RI 2.x mostly doesn't exhibit this behavior any more, * as it declares all statically known namespace URIs (those URIs * that are used as element/attribute names in JAXB annotations), * but it may still declare additional namespaces in the middle of * a document, for example when (i) a QName as an attribute/element value * requires a new namespace URI, or (ii) DOM nodes as a portion of an object * tree requires a new namespace URI. * *
* If you know in advance that you are going to use a certain set of * namespace URIs, you can override this method and have the marshaller * declare those namespace URIs at the root element. * *
* For example, by returning new String[]{"urn:foo"},
* the marshaller will produce:
*
{@code
*
*
* ...
* ...
* ...
* ...
*
* }
*
* To control prefixes assigned to those namespace URIs, use the
* {@link #getPreferredPrefix(String, String, boolean)} method.
*
* @return
* A list of namespace URIs as an array of {@link String}s.
* This method can return a length-zero array but not null.
* None of the array component can be null. To represent
* the empty namespace, use the empty string "".
*
* @since
* JAXB RI 1.0.2
*/
public String[] getPreDeclaredNamespaceUris() {
return EMPTY_STRING;
}
/**
* Similar to {@link #getPreDeclaredNamespaceUris()} but allows the
* (prefix,nsUri) pairs to be returned.
*
*
* With {@link #getPreDeclaredNamespaceUris()}, applications who wish to control * the prefixes as well as the namespaces needed to implement both * {@link #getPreDeclaredNamespaceUris()} and {@link #getPreferredPrefix(String, String, boolean)}. * *
* This version eliminates the needs by returning an array of pairs. * * @return * always return a non-null (but possibly empty) array. The array stores * data like (prefix1,nsUri1,prefix2,nsUri2,...) Use an empty string to represent * the empty namespace URI and the default prefix. Null is not allowed as a value * in the array. * * @since * JAXB RI 2.0 beta */ public String[] getPreDeclaredNamespaceUris2() { return EMPTY_STRING; } /** * Returns a list of (prefix,namespace URI) pairs that represents * namespace bindings available on ancestor elements (that need not be repeated * by the JAXB RI.) * *
* Sometimes JAXB is used to marshal an XML document, which will be * used as a subtree of a bigger document. When this happens, it's nice * for a JAXB marshaller to be able to use in-scope namespace bindings * of the larger document and avoid declaring redundant namespace URIs. * *
* This is automatically done when you are marshalling to {@link XMLStreamWriter}, * {@link XMLEventWriter}, {@link DOMResult}, or {@link Node}, because * those output format allows us to inspect what's currently available * as in-scope namespace binding. However, with other output format, * such as {@link OutputStream}, the JAXB RI cannot do this automatically. * That's when this method comes into play. * *
* Namespace bindings returned by this method will be used by the JAXB RI, * but will not be re-declared. They are assumed to be available when you insert * this subtree into a bigger document. * *
* It is NOT OK to return the same binding, or give * the receiver a conflicting binding information. * It's a responsibility of the caller to make sure that this doesn't happen * even if the ancestor elements look like: *
{@code
*
*
*
* ... JAXB marshalling into here.
*
*
*
* }
*
* @return
* always return a non-null (but possibly empty) array. The array stores
* data like (prefix1,nsUri1,prefix2,nsUri2,...) Use an empty string to represent
* the empty namespace URI and the default prefix. Null is not allowed as a value
* in the array.
*
* @since JAXB RI 2.0 beta
*/
public String[] getContextualNamespaceDecls() {
return EMPTY_STRING;
}
}