The java.util.zip package in Java provides classes for reading and writing standard ZIP and GZIP file formats. It’s part of the java.util package and includes a set of tools for compressing and decompressing data. This package is crucial for handling file compression and decompression operations in Java applications.
Key Classes in java.util.zip
- ZipEntry: Represents a single entry in a ZIP file. It holds information about the file or directory entry, such as its name, size, and other metadata.
- ZipFile: Represents a ZIP file. It allows reading the contents of a ZIP file and accessing individual entries. It also provides methods to extract entries.
- ZipInputStream: A FilterInputStream that reads ZIP file entries sequentially. It allows reading data from ZIP files in a streaming fashion.
- ZipOutputStream: A FilterOutputStream that writes data to a ZIP file. It allows adding entries and compressing data to be stored in the ZIP format.
- GZIPInputStream: A FilterInputStream that reads data from a GZIP-compressed input stream. It supports decompressing data compressed using the GZIP format.
- GZIPOutputStream: A FilterOutputStream that writes data to a GZIP-compressed output stream. It supports compressing data using the GZIP format.
How java.util.zip Works
- Creating ZIP Files: To create a ZIP file, you use ZipOutputStream. You can add entries to the ZIP file by creating ZipEntry instances and writing data to them. Once all entries are added, you close the ZipOutputStream, which finalizes the ZIP file.
- Reading ZIP Files: To read a ZIP file, you use ZipFile or ZipInputStream. With ZipFile, you can access entries and read their contents. With ZipInputStream, you read the ZIP file sequentially, processing each entry as it is read.
- GZIP Compression and Decompression: GZIP is used for compressing and decompressing single files or streams. GZIPOutputStream is used for compressing data, and GZIPInputStream is used for decompressing data.
The java.util.zip package provides a robust set of tools for handling ZIP and GZIP formats. It supports creating, reading, and writing compressed files efficiently, making it a valuable component for file compression and decompression in Java applications.