javautilzipZipInputStream

java.util.zip is a Java standard library package that provides basic support for reading and writing ZIP and GZIP compressed data. It implements the ZIP file format, commonly used to bundle multiple files into a single archive. The package offers classes for both input and output streams, enabling both random-access and streaming processing of ZIP archives. It relies on the Deflate compression method by default but also supports the STORED method for uncompressed entries.

Key classes include ZipFile for reading a ZIP archive from a file, ZipInputStream for streaming entry-by-entry processing from any input stream, and ZipOutputStream for creating or updating ZIP files. ZipEntry represents an individual file or directory within the archive and carries metadata such as name, size, compressed size, and CRC. Supporting classes such as CRC32 and Adler32 compute checksums, while Deflater and Inflater perform compression and decompression. ZipException signals ZIP-specific errors.

To read, open a ZipFile or wrap a ZipInputStream around a source, iterate entries, and extract data from the entry's input stream. To write, wrap a ZipOutputStream around a file output stream, create a ZipEntry for each item, call putNextEntry, write bytes, and call closeEntry. When using the STORED method, you must set entry size, CRC, and compressed size before finishing the entry.

Limitations include lack of built-in support for ZIP encryption in the standard API; performance depends on I/O and compression settings. For advanced features or ZIP64 support, third-party libraries such as Apache Commons Compress offer more options.