Package org.geotools.api.data

Interface FeatureReader<T extends FeatureType,F extends Feature>

All Superinterfaces:
AutoCloseable, Closeable
All Known Subinterfaces:
DelegatingFeatureReader<T,F>, SimpleFeatureReader
All Known Implementing Classes:
AssetsMappingReader, CollectionFeatureReader, CollectionReader, CSVFeatureReader, DefaultFeatureReader, DelegateFeatureReader, DelegateSimpleFeatureReader, DiffFeatureReader, EmptyFeatureReader, EmptySimpleFeatureReader, FCBuffer, FIDFeatureReader, FilteringFeatureReader, FilteringSimpleFeatureReader, ForceCoordinateSystemFeatureReader, GeoJSONFeatureReader, GraticuleFeatureReader, JDBCClosingFeatureReader, JDBCFeatureReader, JDBCInsertFeatureWriter, JDBCJoiningFeatureReader, JDBCJoiningFilteringFeatureReader, JDBCUpdateFeatureWriter, JDBCUpdateInsertFeatureWriter, MaxFeatureReader, MemoryFeatureReader, MongoFeatureReader, PreGeneralizedFeatureReader, PropertyFeatureReader, ReprojectFeatureReader, ReTypeFeatureReader, SortedFeatureReader, VPFFeatureReader, VPFFileFeatureReader
public interface FeatureReader<T extends FeatureType,F extends Feature> extends Closeable
The low-level interface for reading Features. Will use the underlying AttributeReader and the given FeatureType to create new Features.

Typical use is as follows: 


   FeatureReader reader = null;
   try{
      for( reader = data.getFeatureReader( filter ); reader.hasNext(); ){
          f = reader.next();
          ...
      }
   }
   catch (IOException problem){
      ...
   }
   finally {
      if( reader != null ){
          try {
             reader.close();
          }
          catch( IOException eek){
          }
      }
   }

Questions and Suggestions

  • Q: Should FeatureReader provide access to the AttributeReaders it uses?
    A: No, it looks like we will make a lazy Feature in order to cleanly allow for lazy parsing of attribtues.
  • Q:FeatureReader has a close method, but no open method?
    A: This is by design allowing FeatureReader to encapsulate its InputStream or Rowset). Please assume that FeatureReaders are a single use proposition.
  • Q: All that exception handling is a pain! A: Yes it is, we have constructed semi-normal Java iterators to cut down on the pain. But you *do* still have to close 'em - this is IO after all.
  • Q: Can we include skip(int) - SeanG A: The order of the contents is not "known" or predicatable to the end user, so skip( int ) would be useless. For random access (a higher order of abstraction then FeatureReader) please look at FeatureList.
Author:
Ian Schneider, Sean Geoghegan, Defence Science and Technology Organisation.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    close()
    Release the underlying resources associated with this stream.
    T
    getFeatureType()
    Return the FeatureType this reader has been configured to create.
    boolean
    hasNext()
    Query whether this FeatureReader has another Feature.
    F
    next()
    Reads the next Feature in the FeatureReader.

  • Method Details

    • getFeatureType

      T getFeatureType()
      Return the FeatureType this reader has been configured to create.
      Returns:
      the FeatureType of the Features this FeatureReader will create.

    • next

      F next() throws IOException, IllegalArgumentException, NoSuchElementException
      Reads the next Feature in the FeatureReader.
      Returns:
      The next feature in the reader.
      Throws:
      IOException - If an error occurs reading the Feature.
      IllegalAttributeException - If the attributes read do not comply with the FeatureType.
      NoSuchElementException - If there are no more Features in the Reader.
      IllegalArgumentException

    • hasNext

      boolean hasNext() throws IOException
      Query whether this FeatureReader has another Feature.
      Returns:
      True if there are more Features to be read. In other words, true if calls to next would return a feature rather than throwing an exception.
      Throws:
      IOException - If an error occurs determining if there are more Features.

    • close

      void close() throws IOException
      Release the underlying resources associated with this stream.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException - if an I/O error occurs