Package org.geotools.api.data

Interface FeatureWriter<T extends FeatureType,F extends Feature>

All Superinterfaces:
AutoCloseable, Closeable
All Known Subinterfaces:
DelegatingFeatureWriter<T,F>, DelegatingSimpleFeatureWriter, SimpleFeatureWriter
All Known Implementing Classes:
CSVFeatureWriter, DiffContentFeatureWriter, DiffFeatureWriter, EmptyFeatureWriter, EventContentFeatureWriter, FilteringFeatureWriter, GeoJSONFeatureWriter, JDBCClosingFeatureWriter, JDBCInsertFeatureWriter, JDBCUpdateFeatureWriter, JDBCUpdateInsertFeatureWriter, MemoryFeatureWriter, MongoFeatureWriter, PropertyFeatureWriter, WFSFeatureWriter
public interface FeatureWriter<T extends FeatureType,F extends Feature> extends Closeable
Provides the ability to write Features information.

Capabilities:

  • Similar API to FeatureReader
  • After aquiring a feature using next() you may call remove() or after modification write(). If you do not call one of these two methods before calling hasNext(), or next() for that matter, the feature will be left unmodified.
  • This API allows modification, and Filter based modification to be written. Please see ContentDataStore for examples of implementing common opperations using this API.
  • In order to add new Features, FeatureWriters capable of accepting new content allow next() to be called when hasNext() is false to allow new feature creation. These changes

One thing that is really nice about the approach to adding content is that the generation of FID is not left in the users control.

Author:
Ian Schneider, Jody Garnett, Refractions Research

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    close()
    Release the underlying resources.
    T
    getFeatureType()
    FeatureType this reader has been configured to create.
    boolean
    hasNext()
    Query whether this FeatureWriter has another Feature.
    F
    next()
    Reads a Feature from the underlying AttributeReader.
    void
    remove()
    Removes current Feature, must be called before hasNext.
    void
    write()
    Writes the current Feature, must be called before hasNext.

  • Method Details

    • getFeatureType

      T getFeatureType()
      FeatureType this reader has been configured to create.
      Returns:
      FeatureType this writer has been configured to create.

    • next

      F next() throws IOException
      Reads a Feature from the underlying AttributeReader.

      This method may return a Feature even though hasNext() returns false, this allows FeatureWriters to provide an ability to append content.

      Returns:
      Feature from Query, or newly appended Feature
      Throws:
      IOException - if the writer has been closed or an I/O error occurs reading the next Feature.

    • remove

      void remove() throws IOException
      Removes current Feature, must be called before hasNext.

      FeatureWriters will need to allow all FeatureSources of the same typeName to issue a FeatureEvent event of type FeatureEvent.FEATURES_REMOVED when this method is called.

      If this FeatureWriter is opperating against a Transaction FEATURES_REMOVED events should only be sent to FeatureSources operating on the same Transaction. When Transaction commit() is called other FeatureSources will be informed of the modifications.

      When the current Feature has been provided as new content, this method "cancels" the add opperation (and notification needed).

      Throws:
      IOException

    • write

      void write() throws IOException
      Writes the current Feature, must be called before hasNext.

      FeautreWriters will need to allow FeatureSources of the same typeName to issue a FeatureEvent:

      • FeatureEvent.FEATURES_ADDED: when next() has been called with hasNext() equal to false.
      • FeatureEvent.FEATURES_MODIFIED: when next has been called with hasNext() equal to true and the resulting Feature has indeed been modified.

      If this FeatureWriter is opperating against a Transaction the FEATURES_MODIFIED or FEATURES_ADDED events should only be sent to FeatureSources opperating on the same Transaction. When Transaction commit() is called other FeatureSources will be informed of the modifications.

      If you have not called write() when you call hasNext() or next(), no modification will occur().

      Throws:
      IOException

    • hasNext

      boolean hasNext() throws IOException
      Query whether this FeatureWriter has another Feature.

      Please note: it is more efficient to construct your FeatureWriter with a Filer (to skip entries you do not want), than to force the creation of entire Features only to skip over them.

      FeatureWriters that support append operations will allow calls to next, even when hasNext() returns false.

      Returns:
      true if an additional Feature is available, false if not.
      Throws:
      IOException - if an I/O error occurs.

    • close

      void close() throws IOException
      Release the underlying resources.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException - if there there are problems releasing underlying resources, or possibly if close has been called (up to the implementation).
      IOException - if an I/O error occurs