net.java.truelicense.core.io

Interface Transformation

All Known Subinterfaces:

Encryption

All Known Implementing Classes:

BasicPbeEncryption

public interface Transformation

A transformation decorates the OutputStreams and InputStreams which are provided by sinks and sources.

For example, in an encryption transformation, the method apply(net.java.truelicense.core.io.Sink) could decorate the output streams provided by the given sink with a new CipherOutputStream in order to encrypt the data before writing it to the underlying output stream. Likewise, the method unapply(net.java.truelicense.core.io.Source) could decorate the input streams provided by the given source with a new CipherInputStream in order to decrypt the data after reading it from the underlying input stream.

As another example, in a compression transformation, the apply method could decorate the output streams provided by the given sink with a new DeflaterOutputStream in order to compress the data before writing it to the underlying output stream. Likewise, the unapply method could decorate the input streams provided by the given source with a new InflaterInputStream in order to decompress the data after reading it from the underlying input stream.

The benefit of this interface is that you can easily chain the apply and unapply methods in order to create rich decorators for the underlying sinks and sources without needing to know anything about the implementation of the transformations.

For example, depending on the previous examples, the following test code would assert the round-trip processing of the string "Hello world!" using the composition of some compression and encryption transformations on some store:

 Transformation compression = ...;
 Transformation encryption = ...;
 Store store = ...;
 Sink compressAndEncryptData = compression.apply(encryption.apply(store));
 Source decryptAndDecompressData = compression.unapply(encryption.unapply(store));
 try (PrintWriter writer = new PrintWriter(compressAndEncryptData.output())) {
     writer.println("Hello world!");
 }
 try (BufferedReader reader = new BufferedReader(new InputStreamReader(decryptAndDecompressData.input()))) {
     assertTrue("Hello world!".equals(reader.readLine()));
 }
 

Author:

Christian Schlichtherle

Method Summary

Modifier and Type	Method and Description
Sink	apply(Sink sink) Returns a sink which decorates the output streams provided by the given sink.
Source	unapply(Source source) Returns a source which decorates the input streams provided by the given source.

Method Detail

apply

Sink apply(Sink sink)

Returns a sink which decorates the output streams provided by the given sink.

Parameters:

sink - the sink which provides the output streams to decorate.

unapply

Source unapply(Source source)

Returns a source which decorates the input streams provided by the given source.

Parameters:

source - the source which provides the input streams to decorate.