public class PGPCompressedDataGenerator extends java.lang.Object implements CompressionAlgorithmTags
A PGPCompressedDataGenerator is used by invoking one of the open functions to create an OutputStream that raw data can be supplied to for compression:
If the data needs to written out in blocks, useopen(OutputStream, byte[]) to create a
packet consisting of a series of compressed data objects (partials).
A PGPCompressedDataGenerator is usually used to wrap the OutputStream
obtained from a
PGPEncryptedDataGenerator (i.e. to compress data prior to encrypting it).
Raw data is not typically written directly to the OutputStream obtained from a
PGPCompressedDataGenerator. The OutputStream is usually wrapped by a
PGPLiteralDataGenerator, which encodes the raw data prior to compression.
Once data for compression has been written to the constructed OutputStream, writing of the object
stream is completed by closing the OutputStream obtained from the #open() method, or
equivalently invoking close() on this generator.
BZIP2, UNCOMPRESSED, ZIP, ZLIB| Constructor and Description |
|---|
PGPCompressedDataGenerator(int algorithm)
Construct a new compressed data generator.
|
PGPCompressedDataGenerator(int algorithm,
int compression)
Construct a new compressed data generator.
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| Modifier and Type | Method and Description |
|---|---|
void |
close()
Close the compressed object - this is equivalent to calling close on the stream
returned by the open() method.
|
java.io.OutputStream |
open(java.io.OutputStream out)
Return an OutputStream which will save the data being written to
the compressed object.
|
java.io.OutputStream |
open(java.io.OutputStream out,
byte[] buffer)
Return an OutputStream which will compress the data as it is written to it.
|
public PGPCompressedDataGenerator(int algorithm)
algorithm - the identifier of the compression algorithm
to use.public PGPCompressedDataGenerator(int algorithm,
int compression)
algorithm - the identifier of the compression algorithm
to use.compression - the Deflater compression level to use.public java.io.OutputStream open(java.io.OutputStream out)
throws java.io.IOException
The stream created can be closed off by either calling close() on the stream or close() on the generator. Closing the returned stream does not close off the OutputStream parameter out.
out - underlying OutputStream to be used.java.io.IOExceptionjava.lang.IllegalStateExceptionpublic java.io.OutputStream open(java.io.OutputStream out,
byte[] buffer)
throws java.io.IOException,
PGPException
The stream created can be closed off by either calling close() on the stream or close() on the generator. Closing the returned stream does not close off the OutputStream parameter out.
Note: if the buffer is not a power of 2 in length only the largest power of 2 bytes worth of the buffer will be used.
Note: using this may break compatibility with RFC 1991 compliant tools. Only recent OpenPGP implementations are capable of accepting these streams.
out - the stream to write compressed packets to.buffer - a buffer to use to buffer and write partial packets. The returned stream takes
ownership of the buffer and will use it to buffer plaintext data for compression.java.io.IOException - if an error occurs writing stream header information to the provider
output stream.PGPExceptionjava.lang.IllegalStateException - if this generator already has an open OutputStream.public void close()
throws java.io.IOException
java.io.IOException