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<HTML><HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <META NAME="GENERATOR" CONTENT="Mozilla/4.05 [en] (X11; I; SunOS 5.6 sun4u) [Netscape]"> <TITLE>Java(tm) Communications API Users Guide</TITLE></HEAD><BODY BGCOLOR="#FFFFFF"><!-- @(#)API_users_guide.html 1.11 97/12/15 --><center><H1>Java(tm) Communications API Users Guide</H1><I>Version 2.0</I><p><A HREF="../COMM2.0_license.txt">License</A></center><P>This document provides an overview of the components of the Java(tm) communicationsAPI, which is a standard extension to the Java platform. It is not a tutorial;readers should know the basics of serial and parallel port programming,and be comfortable reading the Java communications API <A HREF="packages.html">referencepages</A>.<P>Like all Java standard extensions, the Java communications API is intended to be implementable from specification by third parties.<P><HR><H2><TT>javax.comm</TT> Extension Package</H2><P>There are three levels of classes in the Java communications API:<UL><LI>High-level classes like <TT>CommPortIdentifier</TT> and <TT>CommPort</TT>manage access and ownership of communication ports.</LI><LI>Low-level classes like <TT>SerialPort</TT> and <TT>ParallelPort</TT> providean interface to physical communications ports. The current release of theJava communications API enables access to serial (RS-232) andparallel (IEEE 1284) ports.</LI><LI>Driver-level classes provide an interface between the low-level classesand the underlying operating system. Driver-level classes are part of theimplementation but not the Java communications API. They shouldnot be used by application programmers.</LI></UL>The <TT>javax.comm</TT> package provides the following basic services:<UL><LI>Enumerate the available ports on the system. The static method <TT>CommPortIdentifier.getPortIdentifiers</TT>returns an enumeration object that contains a <TT>CommPortIdentifier</TT>object for each available port. This <TT>CommPortIdentifier</TT> objectis the central mechanism for controlling access to a communications port.</LI><LI>Open and claim ownership of communications ports by using the high levelmethods in their <TT>CommPortIdentifier</TT> objects.</LI><LI>Resolve port ownership contention between multiple Java applications. Eventsare propagated to notify interested applications of ownership contentionand allow the port's owner to relinquish ownership. <TT>PortInUseException</TT>is thrown when an application fails to open the port.</LI><LI>Perform asynchronous and synchronous I/O on communications ports. Low-levelclasses like <TT>SerialPort</TT> and <TT>ParallelPort</TT> have methodsfor managing I/O on communications ports.</LI><LI>Receive events describing communication port state changes. For example,when a serial port has a state change for Carrier Detect, Ring Indicator,DTR, etc. the <TT>SerialPort</TT> object propagates a <TT>SerialPortEvent</TT>that describes the state change.</LI></UL><H2>A Simple Reading Example</H2><TT><A HREF="../samples/Simple/SimpleRead.java">SimpleRead.java</A></TT> opensa serial port and creates a thread for asynchronously reading data throughan event callback technique.<H2>A Simple Writing Example</H2><TT><A HREF="../samples/Simple/SimpleWrite.java">SimpleWrite.java</A></TT>opens a serial port for writing data.<H2>Solaris Notes</H2>The Solaris implementation of the Java communications API requiresthe <A HREF="http://java.sun.com/products/jdk/1.1/">Solaris Native ThreadsPack</A> for JDK 1.1.x.<P>Here's how to test the <TT>SimpleRead.java</TT> example above on Solaris:<OL><LI>Attach a null-modem cable between two serial ports.</LI><LI>Start <TT>tip</TT>(1) on one of the serial ports:</LI><PRE>% tip -9600 /dev/term/b</PRE><LI>Compile <TT>SimpleRead.java</TT>:</LI><PRE>% javac SimpleRead.java</PRE><LI>Run <TT>SimpleRead</TT>:</LI><PRE>% java -native SimpleRead</PRE><LI>Type text into the <TT>tip</TT>(1) window.</LI></OL><HR><FONT SIZE="1">Copyright © 1998 <A HREF="http://www.sun.com">Sun Microsystems, Inc.</A><BR>All Rights Reserved.</FONT></BODY></HTML>⌨️ 快捷键说明
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