1 /* 2 * Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.nio.channels; 27 28 import java.net.InetAddress; 29 import java.net.NetworkInterface; 30 import java.io.IOException; 31 32 /** 33 * A token representing the membership of an Internet Protocol (IP) multicast 34 * group. 35 * 36 * <p> A membership key may represent a membership to receive all datagrams sent 37 * to the group, or it may be <em>source-specific</em>, meaning that it 38 * represents a membership that receives only datagrams from a specific source 39 * address. Whether or not a membership key is source-specific may be determined 40 * by invoking its {@link #sourceAddress() sourceAddress} method. 41 * 42 * <p> A membership key is valid upon creation and remains valid until the 43 * membership is dropped by invoking the {@link #drop() drop} method, or 44 * the channel is closed. The validity of the membership key may be tested 45 * by invoking its {@link #isValid() isValid} method. 46 * 47 * <p> Where a membership key is not source-specific and the underlying operation 48 * system supports source filtering, then the {@link #block block} and {@link 49 * #unblock unblock} methods can be used to block or unblock multicast datagrams 50 * from particular source addresses. 51 * 52 * @see MulticastChannel 53 * 54 * @since 1.7 55 */ 56 public abstract class MembershipKey { 57 58 /** 59 * Initializes a new instance of this class. 60 */ 61 protected MembershipKey() { 62 } 63 64 /** 65 * Tells whether or not this membership is valid. 66 * 67 * <p> A multicast group membership is valid upon creation and remains 68 * valid until the membership is dropped by invoking the {@link #drop() drop} 69 * method, or the channel is closed. 70 * 71 * @return {@code true} if this membership key is valid, {@code false} 72 * otherwise 73 */ 74 public abstract boolean isValid(); 75 76 /** 77 * Drop membership. 78 * 79 * <p> If the membership key represents a membership to receive all datagrams 80 * then the membership is dropped and the channel will no longer receive any 81 * datagrams sent to the group. If the membership key is source-specific 82 * then the channel will no longer receive datagrams sent to the group from 83 * that source address. 84 * 85 * <p> After membership is dropped it may still be possible to receive 86 * datagrams sent to the group. This can arise when datagrams are waiting to 87 * be received in the socket's receive buffer. After membership is dropped 88 * then the channel may {@link MulticastChannel#join join} the group again 89 * in which case a new membership key is returned. 90 * 91 * <p> Upon return, this membership object will be {@link #isValid() invalid}. 92 * If the multicast group membership is already invalid then invoking this 93 * method has no effect. Once a multicast group membership is invalid, 94 * it remains invalid forever. 95 */ 96 public abstract void drop(); 97 98 /** 99 * Block multicast datagrams from the given source address. 100 * 101 * <p> If this membership key is not source-specific, and the underlying 102 * operating system supports source filtering, then this method blocks 103 * multicast datagrams from the given source address. If the given source 104 * address is already blocked then this method has no effect. 105 * After a source address is blocked it may still be possible to receive 106 * datagrams from that source. This can arise when datagrams are waiting to 107 * be received in the socket's receive buffer. 108 * 109 * @param source 110 * The source address to block 111 * 112 * @return This membership key 113 * 114 * @throws IllegalArgumentException 115 * If the {@code source} parameter is not a unicast address or 116 * is not the same address type as the multicast group 117 * @throws IllegalStateException 118 * If this membership key is source-specific or is no longer valid 119 * @throws UnsupportedOperationException 120 * If the underlying operating system does not support source 121 * filtering 122 * @throws IOException 123 * If an I/O error occurs 124 */ 125 public abstract MembershipKey block(InetAddress source) throws IOException; 126 127 /** 128 * Unblock multicast datagrams from the given source address that was 129 * previously blocked using the {@link #block(InetAddress) block} method. 130 * 131 * @param source 132 * The source address to unblock 133 * 134 * @return This membership key 135 * 136 * @throws IllegalStateException 137 * If the given source address is not currently blocked or the 138 * membership key is no longer valid 139 */ 140 public abstract MembershipKey unblock(InetAddress source); 141 142 /** 143 * Returns the channel for which this membership key was created. This 144 * method will continue to return the channel even after the membership 145 * becomes {@link #isValid invalid}. 146 * 147 * @return the channel 148 */ 149 public abstract MulticastChannel channel(); 150 151 /** 152 * Returns the multicast group for which this membership key was created. 153 * This method will continue to return the group even after the membership 154 * becomes {@link #isValid invalid}. 155 * 156 * @return the multicast group 157 */ 158 public abstract InetAddress group(); 159 160 /** 161 * Returns the network interface for which this membership key was created. 162 * This method will continue to return the network interface even after the 163 * membership becomes {@link #isValid invalid}. 164 * 165 * @return the network interface 166 */ 167 public abstract NetworkInterface networkInterface(); 168 169 /** 170 * Returns the source address if this membership key is source-specific, 171 * or {@code null} if this membership is not source-specific. 172 * 173 * @return The source address if this membership key is source-specific, 174 * otherwise {@code null} 175 */ 176 public abstract InetAddress sourceAddress(); 177 } 178
