javautilzip

The java.util.zip package is part of the Java Standard Edition API and provides a set of classes for handling compressed data, especially ZIP archives and GZIP streams. It includes streaming implementations such as ZipInputStream and ZipOutputStream, the ZipFile class for random access to ZIP archives, and GZIPInputStream and GZIPOutputStream for single-file gzip compression. The package also contains the Deflater and Inflater engines and their corresponding stream wrappers, DeflaterOutputStream and InflaterInputStream, which perform the core compression and decompression in a streaming fashion. For data integrity, it provides checksum utilities such as CRC32 and Adler32, as well as support classes like CheckedInputStream and CheckedOutputStream that calculate checksums on the fly. The ZIP archive representation is exposed through ZipEntry and ZipFile, which provide metadata for entries and methods to read or write them.

Usage overview: ZipInputStream reads entries sequentially from a ZIP archive as a stream, suitable for streaming processing; ZipFile offers random access to entries by name or index. GZIPInputStream and GZIPOutputStream handle a single compressed data stream, typically used for a single file. The Deflater and Inflater engines support manual compression and decompression, while the wrapper streams enable incremental processing.

The package is maintained as part of the Java SE platform and is designed to be cross-platform within the Java ecosystem. It provides a stable API for reading, creating, and manipulating compressed data and archives, along with utilities to verify data integrity through checksums.