1 /* 2 * @(#)Channel.java 1.18 03/12/19 3 * 4 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 5 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. 6 */ 7 8 package java.nio.channels; 9 10 import java.io.IOException; 11 import java.io.Closeable; 12 13 14 /** 15 * A nexus for I/O operations. 16 * 17 * <p> A channel represents an open connection to an entity such as a hardware 18 * device, a file, a network socket, or a program component that is capable of 19 * performing one or more distinct I/O operations, for example reading or 20 * writing. 21 * 22 * <p> A channel is either open or closed. A channel is open upon creation, 23 * and once closed it remains closed. Once a channel is closed, any attempt to 24 * invoke an I/O operation upon it will cause a {@link ClosedChannelException} 25 * to be thrown. Whether or not a channel is open may be tested by invoking 26 * its {@link #isOpen isOpen} method. 27 * 28 * <p> Channels are, in general, intended to be safe for multithreaded access 29 * as described in the specifications of the interfaces and classes that extend 30 * and implement this interface. 31 * 32 * 33 * @author Mark Reinhold 34 * @author JSR-51 Expert Group 35 * @version 1.18, 03/12/19 36 * @since 1.4 37 */ 38 39 public interface Channel extends Closeable { 40 41 /** 42 * Tells whether or not this channel is open. </p> 43 * 44 * @return <tt>true</tt> if, and only if, this channel is open 45 */ 46 public boolean isOpen(); 47 48 /** 49 * Closes this channel. 50 * 51 * <p> After a channel is closed, any further attempt to invoke I/O 52 * operations upon it will cause a {@link ClosedChannelException} to be 53 * thrown. 54 * 55 * <p> If this channel is already closed then invoking this method has no 56 * effect. 57 * 58 * <p> This method may be invoked at any time. If some other thread has 59 * already invoked it, however, then another invocation will block until 60 * the first invocation is complete, after which it will return without 61 * effect. </p> 62 * 63 * @throws IOException If an I/O error occurs 64 */ 65 public void close() throws IOException; 66 67 } 68