Package org.geotools.data.shapefile.shp

Class ShapefileReader

Object
ShapefileReader
All Implemented Interfaces:
Closeable, AutoCloseable, FileReader
public class ShapefileReader extends Object implements FileReader, Closeable
The general use of this class is: 

 FileChannel in = new FileInputStream("thefile.dbf").getChannel();
 ShapefileReader r = new ShapefileReader( in ) while (r.hasNext()) { Geometry
 shape = (Geometry) r.nextRecord().shape() // do stuff } r.close();
You don't have to immediately ask for the shape from the record. The record will contain the bounds of the shape and will only read the shape when the shape() method is called. This ShapefileReader.Record is the same object every time, so if you need data from the Record, be sure to copy it.
Author:
jamesm, aaime, Ian Schneider

  • Constructor Details

    • ShapefileReader

      public ShapefileReader(ShpFiles shapefileFiles, boolean strict, boolean useMemoryMapped, GeometryFactory gf) throws IOException, ShapefileException
      Creates a new instance of ShapeFile.
      Parameters:
      shapefileFiles - The ReadableByteChannel this reader will use.
      strict - True to make the header parsing throw Exceptions if the version or magic number are incorrect.
      Throws:
      IOException - If problems arise.
      ShapefileException - If for some reason the file contains invalid records.

    • ShapefileReader

      public ShapefileReader(ShpFiles shapefileFiles, boolean strict, boolean useMemoryMapped, GeometryFactory gf, boolean onlyRandomAccess) throws IOException, ShapefileException
      Creates a new instance of ShapeFile.
      Parameters:
      shapefileFiles - The ReadableByteChannel this reader will use.
      strict - True to make the header parsing throw Exceptions if the version or magic number are incorrect.
      useMemoryMapped - Wheter to enable memory mapping or not
      gf - The geometry factory used to build the geometries
      onlyRandomAccess - When true sets up the reader to do exclusively read driven by goTo(x) and thus avoids opening the .shx file
      Throws:
      IOException - If problems arise.
      ShapefileException - If for some reason the file contains invalid records.

  • Method Details

    • disableShxUsage

      public void disableShxUsage() throws IOException
      Disables .shx file usage. By doing so you drop support for sparse shapefiles, the .shp will have to be without holes, all the valid shapefile records will have to be contiguous.
      Throws:
      IOException

    • fill

      public static int fill(ByteBuffer buffer, ReadableByteChannel channel) throws IOException
      Throws:
      IOException

    • getHeader

      public ShapefileHeader getHeader()
      Get the header. Its parsed in the constructor.
      Returns:
      The header that is associated with this file.

    • close

      public void close() throws IOException
      Clean up any resources. Closes the channel.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException - If errors occur while closing the channel.

    • supportsRandomAccess

      public boolean supportsRandomAccess()

    • hasNext

      public boolean hasNext() throws IOException
      If there exists another record. Currently checks the stream for the presence of 8 more bytes, the length of a record. If this is true and the record indicates the next logical record number, there exists more records.
      Returns:
      True if has next record, false otherwise.
      Throws:
      IOException

    • transferTo

      public int transferTo(ShapefileWriter writer, int recordNum, double[] bounds) throws IOException
      Transfer (by bytes) the data at the current record to the ShapefileWriter.
      Parameters:
      bounds - double array of length four for transfering the bounds into
      Returns:
      The length of the record transfered in bytes
      Throws:
      IOException

    • nextRecord

      public ShapefileReader.Record nextRecord() throws IOException
      Fetch the next record information.
      Returns:
      The record instance associated with this reader.
      Throws:
      IOException

    • goTo

      public void goTo(int offset) throws IOException, UnsupportedOperationException
      Moves the reader to the specified byte offset in the file. Mind that:
      • it's your responsibility to ensure the offset corresponds to the actual beginning of a shape struct
      • once you call this, reading with hasNext/next on sparse shapefiles will be broken (we don't know anymore at which shape we are)
      Throws:
      IOException
      UnsupportedOperationException

    • shapeAt

      public Object shapeAt(int offset) throws IOException, UnsupportedOperationException
      Returns the shape at the specified byte distance from the beginning of the file. Mind that:
      • it's your responsibility to ensure the offset corresponds to the actual beginning of a shape struct
      • once you call this, reading with hasNext/next on sparse shapefiles will be broken (we don't know anymore at which shape we are)
      Throws:
      IOException
      UnsupportedOperationException

    • recordAt

      public ShapefileReader.Record recordAt(int offset) throws IOException, UnsupportedOperationException
      Sets the current location of the byteStream to offset and returns the next record. Usually used in conjuctions with the shx file or some other index file. Mind that:
      • it's your responsibility to ensure the offset corresponds to the actual beginning of a shape struct
      • once you call this, reading with hasNext/next on sparse shapefiles will be broken (we don't know anymore at which shape we are)
      Parameters:
      offset - If using an shx file the offset would be: 2 * (index.getOffset(i))
      Returns:
      The record after the offset location in the bytestream
      Throws:
      IOException - thrown in a read error occurs
      UnsupportedOperationException - thrown if not a random access file

    • getCount

      public int getCount(int count) throws DataSourceException
      Parses the shpfile counting the records.
      Returns:
      the number of non-null records in the shapefile
      Throws:
      DataSourceException

    • setHandler

      public void setHandler(ShapeHandler handler)
      Parameters:
      handler - The handler to set.

    • id

      public String id()
      Description copied from interface: FileReader
      An id for the reader. This is only used for debugging.
      Specified by:
      id in interface FileReader
      Returns:
      id for the reader.

    • setFlatGeometry

      public void setFlatGeometry(boolean flatGeometry)