org.opengis.coverage.grid

Interface GridCoverageReader

public interface GridCoverageReader

Support for reading grid coverages out of a persisten store. Instance of GridCoverageReader are obtained through a call to GridCoverageExchange.getReader(java.lang.Object). Grid coverages are usually read from the input stream in a sequential order.

WARNING: THIS CLASS WILL CHANGE. Current API is derived from OGC Grid Coverages Implementation specification 1.0. We plan to replace it by new interfaces derived from ISO 19123 (Schema for coverage geometry and functions). Current interfaces should be considered as legacy and are included in this distribution only because they were part of GeoAPI 1.0 release. We will try to preserve as much compatibility as possible, but no migration plan has been determined yet.

Since:

GeoAPI 2.0

See Also:

GridCoverageExchange.getReader(java.lang.Object), ImageReader

Method Summary

Modifier and Type	Method and Description
void	dispose() Allows any resources held by this object to be released.
java.lang.String	getCurrentSubname() Returns the name for the next grid coverage to be read from the input source.
Format	getFormat() Returns the format handled by this GridCoverageReader.
java.lang.String[]	getMetadataNames() Returns the list of metadata keywords associated with the input source as a whole (not associated with any particular grid coverage).
java.lang.String	getMetadataValue(java.lang.String name) Retrieve the metadata value for a given metadata name.
java.lang.Object	getSource() Returns the input source.
boolean	hasMoreGridCoverages() Returns true if there is at least one more grid coverage available on the stream.
java.lang.String[]	listSubNames() Retrieve the list of grid coverages contained within the input source.
GridCoverage	read(GeneralParameterValue[] parameters) Read the grid coverage from the current stream position, and move to the next grid coverage.
void	skip() Skip the current grid coverage without reading it, and move the stream position to the next grid coverage.

Method Detail

getFormat

Format getFormat()

Returns the format handled by this GridCoverageReader.

getSource

java.lang.Object getSource()

Returns the input source. This is the object passed to the GridCoverageExchange.getReader(java.lang.Object) method. It can be a String, an InputStream, a FileChannel, whatever.

getMetadataNames

java.lang.String[] getMetadataNames()
                             throws java.io.IOException

Returns the list of metadata keywords associated with the input source as a whole (not associated with any particular grid coverage). If no metadata is available, the array will be empty.

Returns:

The list of metadata keywords for the input source.

Throws:

java.io.IOException - if an error occurs during reading.

getMetadataValue

java.lang.String getMetadataValue(java.lang.String name)
                           throws java.io.IOException,
                                  MetadataNameNotFoundException

Retrieve the metadata value for a given metadata name.

Parameters:

name - Metadata keyword for which to retrieve metadata.

Returns:

The metadata value for the given metadata name. Should be one of the name returned by getMetadataNames().

Throws:

java.io.IOException - if an error occurs during reading.

MetadataNameNotFoundException - if there is no value for the specified metadata name.

listSubNames

java.lang.String[] listSubNames()
                         throws java.io.IOException

Retrieve the list of grid coverages contained within the input source. Each grid can have a different coordinate system, number of dimensions and grid geometry. For example, a HDF-EOS file (GRID.HDF) contains 6 grid coverages each having a different projection. An empty array will be returned if no sub names exist.

Returns:

The list of grid coverages contained within the input source.

Throws:

java.io.IOException - if an error occurs during reading.

getCurrentSubname

java.lang.String getCurrentSubname()
                            throws java.io.IOException

Returns the name for the next grid coverage to be read from the input source.

Throws:

java.io.IOException - if an error occurs during reading.

hasMoreGridCoverages

boolean hasMoreGridCoverages()
                      throws java.io.IOException

Returns true if there is at least one more grid coverage available on the stream.

Throws:

java.io.IOException

read

GridCoverage read(GeneralParameterValue[] parameters)
           throws java.lang.IllegalArgumentException,
                  java.io.IOException

Read the grid coverage from the current stream position, and move to the next grid coverage. The method hasMoreGridCoverages() should be invoked first in order to verify that a coverage is available.

Parameters:

parameters - An optional set of parameters. Should be any or all of the parameters returned by Format.getReadParameters().

Returns:

A new grid coverage from the input source.

Throws:

InvalidParameterNameException - if a parameter in parameters doesn't have a recognized name.

InvalidParameterValueException - if a parameter in parameters doesn't have a valid value.

ParameterNotFoundException - if a parameter was required for the operation but was not provided in the parameters list.

CannotCreateGridCoverageException - if the coverage can't be created for a logical reason (for example an unsupported format, or an inconsistency found in the data).

java.io.IOException - if a read operation failed for some other input/output reason, including FileNotFoundException if no file with the given name can be found, or IIOException if an error was thrown by the underlying image library.

java.lang.IllegalArgumentException

skip

void skip()
   throws java.io.IOException

Skip the current grid coverage without reading it, and move the stream position to the next grid coverage.

Throws:

java.io.IOException - if the operation failed.

dispose

void dispose()
      throws java.io.IOException

Allows any resources held by this object to be released. The result of calling any other method subsequent to a call to this method is undefined. It is important for applications to call this method when they know they will no longer be using this GridCoverageReader. Otherwise, the reader may continue to hold on to resources indefinitely.

Throws:

java.io.IOException - if an error occured while disposing resources (for example while closing a file).