JDK 1.4 Tutorial, eDoc 1 : Exploring Channels and Buffers in the New I/O

The New I/O (NIO) Library included in JDK 1.4 represents a revolution in the way that Java programs read and write data. The new channel and buffer classes allow for production-level efficiency while still maintaining full cross-platform portability. And if you think you won't use them, think again -- the stream classes have been re-implemented on top of NIO.

This e-doc will guide you through the nitty-gritty of the new channel and buffer classes, showing you how they work and how to use them to accomplish staple I/O tasks. It also outlines some of the exciting new features that are made possible by NIO -- including memory-mapped files and non-blocking I/O.

This e-doc will show you how to:

• Create and use channels and buffers
• Access efficient system-level I/O buffers
• Lock files and portions of files
• Copy files quickly
• Use MappedByteBuffers
• Translate text data between different encodings
• Determine what network interfaces exist on a computer

Sample programs included in this chapter:

• A network TCP/IP forwarder
• A simple database that uses file locking
• A chat (instant messaging) server, implemented efficiently using selectors
• A utility for converting data between any two charsets