Package org.geotools.data.shapefile.dbf

Class DbaseFileReader

  • All Implemented Interfaces:
    Closeable, AutoCloseable, FileReader
    Direct Known Subclasses:
    IndexedDbaseFileReader
    public class DbaseFileReader
extends Object
implements FileReader, Closeable
    A DbaseFileReader is used to read a dbase III format file.
    The general use of this class is: 
    
 FileChannel in = new FileInputStream("thefile.dbf").getChannel();
 DbaseFileReader r = new DbaseFileReader( in ) Object[] fields = new
 Object[r.getHeader().getNumFields()]; while (r.hasNext()) {
 r.readEntry(fields); // do stuff } r.close();
    For consumers who wish to be a bit more selective with their reading of rows, the Row object has been added. The semantics are the same as using the readEntry method, but remember that the Row object is always the same. The values are parsed as they are read, so it pays to copy them out (as each call to Row.read() will result in an expensive String parse).
    EACH CALL TO readEntry OR readRow ADVANCES THE FILE!
    An example of using the Row method of reading: 
    
 FileChannel in = new FileInputStream("thefile.dbf").getChannel();
 DbaseFileReader r = new DbaseFileReader( in ) int fields =
 r.getHeader().getNumFields(); while (r.hasNext()) { DbaseFileReader.Row row =
 r.readRow(); for (int i = 0; i < fields; i++) { // do stuff Foo.bar(
 row.read(i) ); } } r.close();
    Author:
    Ian Schneider, Andrea Aaime

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      class  DbaseFileReader.Row  

    • Constructor Summary

      Constructors 
      Constructor Description
      DbaseFileReader​(ReadableByteChannel readChannel, boolean useMemoryMappedBuffer, Charset charset)  
      DbaseFileReader​(ReadableByteChannel readChannel, boolean useMemoryMappedBuffer, Charset charset, TimeZone timeZone)  
      DbaseFileReader​(ShpFiles shapefileFiles, boolean useMemoryMappedBuffer, Charset charset)  
      DbaseFileReader​(ShpFiles shapefileFiles, boolean useMemoryMappedBuffer, Charset charset, TimeZone timeZone)
      Creates a new instance of DBaseFileReader

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void close()
      Clean up all resources associated with this reader.Highly recomended.
      protected int fill​(ByteBuffer buffer, ReadableByteChannel channel)  
      DbaseFileHeader getHeader()
      Get the header from this file.
      boolean hasNext()
      Query the reader as to whether there is another record.
      String id()
      An id for the reader.
      static void main​(String[] args)  
      void read()
      Reads the next record into memory.
      Object[] readEntry()
      Get the next record (entry).
      Object[] readEntry​(Object[] entry)
      Copy the next entry into the array.
      Object[] readEntry​(Object[] entry, int offset)
      Copy the next record into the array starting at offset.
      Object readField​(int fieldNum)
      Reads a single field from the current record and returns it.
      DbaseFileReader.Row readRow()  
      void skip()
      Skip the next record.
      void transferTo​(DbaseFileWriter writer)
      Transfer, by bytes, the next record to the writer.

      • Methods inherited from class Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • useMemoryMappedBuffer

        protected boolean useMemoryMappedBuffer

      • randomAccessEnabled

        protected boolean randomAccessEnabled

      • currentOffset

        protected long currentOffset

    • Constructor Detail

      • DbaseFileReader

        public DbaseFileReader​(ShpFiles shapefileFiles,
                       boolean useMemoryMappedBuffer,
                       Charset charset,
                       TimeZone timeZone)
                throws IOException
        Creates a new instance of DBaseFileReader
        Parameters:
        shapefileFiles - The readable channel to use.
        Throws:
        IOException - If an error occurs while initializing.

      • DbaseFileReader

        public DbaseFileReader​(ShpFiles shapefileFiles,
                       boolean useMemoryMappedBuffer,
                       Charset charset)
                throws IOException
        Throws:
        IOException

      • DbaseFileReader

        public DbaseFileReader​(ReadableByteChannel readChannel,
                       boolean useMemoryMappedBuffer,
                       Charset charset)
                throws IOException
        Throws:
        IOException

      • DbaseFileReader

        public DbaseFileReader​(ReadableByteChannel readChannel,
                       boolean useMemoryMappedBuffer,
                       Charset charset,
                       TimeZone timeZone)
                throws IOException
        Throws:
        IOException

    • Method Detail

      • fill

        protected int fill​(ByteBuffer buffer,
                   ReadableByteChannel channel)
            throws IOException
        Throws:
        IOException

      • getHeader

        public DbaseFileHeader getHeader()
        Get the header from this file. The header is read upon instantiation.
        Returns:
        The header associated with this file or null if an error occurred.

      • close

        public void close()
           throws IOException
        Clean up all resources associated with this reader.Highly recomended.
        Specified by:
        close in interface AutoCloseable
        Specified by:
        close in interface Closeable
        Throws:
        IOException - If an error occurs.

      • hasNext

        public boolean hasNext()
        Query the reader as to whether there is another record.
        Returns:
        True if more records exist, false otherwise.

      • readEntry

        public Object[] readEntry()
                   throws IOException
        Get the next record (entry). Will return a new array of values.
        Returns:
        A new array of values.
        Throws:
        IOException - If an error occurs.

      • skip

        public void skip()
          throws IOException
        Skip the next record.
        Throws:
        IOException - If an error occurs.

      • readEntry

        public Object[] readEntry​(Object[] entry,
                          int offset)
                   throws IOException
        Copy the next record into the array starting at offset.
        Parameters:
        entry - Th array to copy into.
        offset - The offset to start at
        Returns:
        The same array passed in.
        Throws:
        IOException - If an error occurs.

      • readField

        public Object readField​(int fieldNum)
                 throws IOException
        Reads a single field from the current record and returns it. Remember to call read() before starting to read fields from the dbf, and call it every time you need to move to the next record.
        Parameters:
        fieldNum - The field number to be read (zero based)
        Returns:
        The value of the field
        Throws:
        IOException - If an error occurs.

      • transferTo

        public void transferTo​(DbaseFileWriter writer)
                throws IOException
        Transfer, by bytes, the next record to the writer.
        Throws:
        IOException

      • read

        public void read()
          throws IOException
        Reads the next record into memory. You need to use this directly when reading only a subset of the fields using readField(int).
        Throws:
        IOException

      • readEntry

        public Object[] readEntry​(Object[] entry)
                   throws IOException
        Copy the next entry into the array.
        Parameters:
        entry - The array to copy into.
        Returns:
        The same array passed in.
        Throws:
        IOException - If an error occurs.

      • main

        public static void main​(String[] args)
                 throws Exception
        Throws:
        Exception

      • 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.