org.apache.axiom.om

## Interface QNameAwareOMDataSource

- All Superinterfaces:
    OMDataSource
  All Known Implementing Classes:
    JAXBOMDataSource, WrappedTextNodeOMDataSource, WrappedTextNodeOMDataSourceFromDataSource, WrappedTextNodeOMDataSourceFromReader

      public interface QNameAwareOMDataSource
      extends OMDataSource

  Optional interface implemented by `OMDataSource` implementations that have knowledge about the local name, namespace URI and/or namespace prefix of the element they represent. This interface is used by `OMSourcedElement` to lazily determine the name of the element without expanding it. The information returned by the implementation may be partial; e.g. the data source may know about the local name and namespace URI but it may be unable to predict the namespace prefix. The returned information must be accurate, i.e. it must match the name of the root element in the document returned by `OMDataSource.getReader()`.

  This interface should be implemented by `OMDataSource` implementations that have an efficient way to determine the root element name (or part of it) from the information effectively used by `OMDataSource.getReader()` to construct the `XMLStreamReader` instance. In practice this applies to `OMDataSource` implementations that satisfy one of the following conditions:

  - The data source wraps another type of object and is able to determine the element name from that object in an efficient way. E.g. this is often the case if the data source uses a Java-to-XML mapping framework to transform the wrapped object into XML.
  - The QName of the element is configurable and supplied by the application code when the data source is instantiated.
  This interface should not be implemented if the returned information would be supplied by the application code when the data source is instantiate, without the data source being able to guarantee that the information is accurate (i.e. without `OMDataSource.getReader()` actually using that information). In fact, in this case the application code should use `OMFactory.createOMElement(OMDataSource, String, OMNamespace)` or `OMFactory.createOMElement(OMDataSource, QName)` to supply the QName information it has.

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `String` | `getLocalName()` Get the local name of the element represented by this data source.
    `String` | `getNamespaceURI()` Get the namespace URI of the element represented by this data source.
    `String` | `getPrefix()` Get the namespace prefix of the element represented by this data source.

    - ### Methods inherited from interface org.apache.axiom.om.OMDataSource

      `getReader, serialize, serialize, serialize`

- - ### Method Detail

    - #### getLocalName

          String getLocalName()

      Get the local name of the element represented by this data source.
      Returns:
        the local name of the element or `null` if the local name is not known

    - #### getNamespaceURI

          String getNamespaceURI()

      Get the namespace URI of the element represented by this data source.
      Returns:
        the namespace URI of the element, the empty string if the element has no namespace or `null` if the namespace URI is not known

    - #### getPrefix

          String getPrefix()

      Get the namespace prefix of the element represented by this data source.
      Returns:
        the prefix of the element, the empty string if the element has no prefix or `null` if the prefix is not known; the implementation is expected to return an empty string if `getNamespaceURI()` returns an empty string (because an element without namespace must not have a prefix)

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