JDK14/Java14源码在线阅读
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package java.net;
import java.io.IOException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Set;
/**
* The multicast datagram socket class is useful for sending
* and receiving IP multicast packets. A MulticastSocket is
* a (UDP) DatagramSocket, with additional capabilities for
* joining "groups" of other multicast hosts on the internet.
* <P>
* A multicast group is specified by a class D IP address
* and by a standard UDP port number. Class D IP addresses
* are in the range {@code 224.0.0.0} to {@code 239.255.255.255},
* inclusive. The address 224.0.0.0 is reserved and should not be used.
* <P>
* One would join a multicast group by first creating a MulticastSocket
* with the desired port, then invoking the
* <CODE>joinGroup(InetAddress groupAddr)</CODE>
* method:
* <PRE>
* // join a Multicast group and send the group salutations
* ...
* String msg = "Hello";
* InetAddress mcastaddr = InetAddress.getByName("228.5.6.7");
* InetSocketAddress group = new InetSocketAddress(mcastaddr, port);
* NetworkInterface netIf = NetworkInterface.getByName("bge0");
* MulticastSocket s = new MulticastSocket(6789);
*
* s.joinGroup(group, netIf);
* byte[] msgBytes = msg.getBytes(StandardCharsets.UTF_8);
* DatagramPacket hi = new DatagramPacket(msgBytes, msgBytes.length,
* group, 6789);
* s.send(hi);
* // get their responses!
* byte[] buf = new byte[1000];
* DatagramPacket recv = new DatagramPacket(buf, buf.length);
* s.receive(recv);
* ...
* // OK, I'm done talking - leave the group...
* s.leaveGroup(group, netIf);
* </PRE>
*
* When one sends a message to a multicast group, <B>all</B> subscribing
* recipients to that host and port receive the message (within the
* time-to-live range of the packet, see below). The socket needn't
* be a member of the multicast group to send messages to it.
* <P>
* When a socket subscribes to a multicast group/port, it receives
* datagrams sent by other hosts to the group/port, as do all other
* members of the group and port. A socket relinquishes membership
* in a group by the leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf)
* method.
* <B>Multiple MulticastSockets</B> may subscribe to a multicast group
* and port concurrently, and they will all receive group datagrams.
*
* <p> The {@code DatagramSocket} and {@code MulticastSocket}
* classes define convenience methods to set and get several
* socket options. Like {@code DatagramSocket} this class also
* supports the {@link #setOption(SocketOption, Object) setOption}
* and {@link #getOption(SocketOption) getOption} methods to set
* and query socket options.
* In addition to the socket options supported by
* <a href="DatagramSocket.html#SocketOptions">{@code DatagramSocket}</a>, a
* {@code MulticastSocket} supports the following socket options:
* <blockquote>
* <a id="MulticastOptions"></a>
* <table class="striped">
* <caption style="display:none">Socket options</caption>
* <thead>
* <tr>
* <th scope="col">Option Name</th>
* <th scope="col">Description</th>
* </tr>
* </thead>
* <tbody>
* <tr>
* <th scope="row"> {@link java.net.StandardSocketOptions#IP_MULTICAST_IF IP_MULTICAST_IF} </th>
* <td> The network interface for Internet Protocol (IP) multicast datagrams </td>
* </tr>
* <tr>
* <th scope="row"> {@link java.net.StandardSocketOptions#IP_MULTICAST_TTL
* IP_MULTICAST_TTL} </th>
* <td> The <em>time-to-live</em> for Internet Protocol (IP) multicast
* datagrams </td>
* </tr>
* <tr>
* <th scope="row"> {@link java.net.StandardSocketOptions#IP_MULTICAST_LOOP
* IP_MULTICAST_LOOP} </th>
* <td> Loopback for Internet Protocol (IP) multicast datagrams </td>
* </tr>
* </tbody>
* </table>
* </blockquote>
* Additional (implementation specific) options may also be supported.
*
* @author Pavani Diwanji
* @since 1.1
*/
public class MulticastSocket extends DatagramSocket {
/**
* Used on some platforms to record if an outgoing interface
* has been set for this socket.
*/
private boolean interfaceSet;
/**
* Create a multicast socket.
*
* <p>
* If there is a security manager, its {@code checkListen} method is first
* called with 0 as its argument to ensure the operation is allowed. This
* could result in a SecurityException.
* <p>
* When the socket is created the
* {@link DatagramSocket#setReuseAddress(boolean)} method is called to
* enable the SO_REUSEADDR socket option.
*
* @throws IOException if an I/O exception occurs while creating the
* MulticastSocket
* @throws SecurityException if a security manager exists and its
* {@code checkListen} method doesn't allow the operation.
* @see SecurityManager#checkListen
* @see java.net.DatagramSocket#setReuseAddress(boolean)
* @see java.net.DatagramSocketImpl#setOption(SocketOption, Object)
*/
public MulticastSocket() throws IOException {
this(new InetSocketAddress(0));
}
/**
* Create a multicast socket and bind it to a specific port.
*
* <p>If there is a security manager,
* its {@code checkListen} method is first called
* with the {@code port} argument
* as its argument to ensure the operation is allowed.
* This could result in a SecurityException.
* <p>
* When the socket is created the
* {@link DatagramSocket#setReuseAddress(boolean)} method is
* called to enable the SO_REUSEADDR socket option.
*
* @param port port to use
* @throws IOException if an I/O exception occurs
* while creating the MulticastSocket
* @throws SecurityException if a security manager exists and its
* {@code checkListen} method doesn't allow the operation.
* @see SecurityManager#checkListen
* @see java.net.DatagramSocket#setReuseAddress(boolean)
*/
public MulticastSocket(int port) throws IOException {
this(new InetSocketAddress(port));
}
/**
* Create a MulticastSocket bound to the specified socket address.
* <p>
* Or, if the address is {@code null}, create an unbound socket.
*
* <p>If there is a security manager,
* its {@code checkListen} method is first called
* with the SocketAddress port as its argument to ensure the operation is allowed.
* This could result in a SecurityException.
* <p>
* When the socket is created the
* {@link DatagramSocket#setReuseAddress(boolean)} method is
* called to enable the SO_REUSEADDR socket option.
*
* @param bindaddr Socket address to bind to, or {@code null} for
* an unbound socket.
* @throws IOException if an I/O exception occurs
* while creating the MulticastSocket
* @throws SecurityException if a security manager exists and its
* {@code checkListen} method doesn't allow the operation.
* @see SecurityManager#checkListen
* @see java.net.DatagramSocket#setReuseAddress(boolean)
*
* @since 1.4
*/
public MulticastSocket(SocketAddress bindaddr) throws IOException {
super((SocketAddress) null);
// Enable SO_REUSEADDR before binding
setReuseAddress(true);
if (bindaddr != null) {
try {
bind(bindaddr);
} finally {
if (!isBound()) {
close();
}
}
}
}
/**
* The lock on the socket's TTL. This is for set/getTTL and
* send(packet,ttl).
*/
private Object ttlLock = new Object();
/**
* The lock on the socket's interface - used by setInterface
* and getInterface
*/
private Object infLock = new Object();
/**
* The "last" interface set by setInterface on this MulticastSocket
*/
private InetAddress infAddress = null;
/**
* Set the default time-to-live for multicast packets sent out
* on this {@code MulticastSocket} in order to control the
* scope of the multicasts.
*
* <p>The ttl is an <b>unsigned</b> 8-bit quantity, and so <B>must</B> be
* in the range {@code 0 <= ttl <= 0xFF }.
*
* @param ttl the time-to-live
* @throws IOException if an I/O exception occurs
* while setting the default time-to-live value
* @deprecated use the setTimeToLive method instead, which uses
* <b>int</b> instead of <b>byte</b> as the type for ttl.
* @see #getTTL()
*/
@Deprecated
public void setTTL(byte ttl) throws IOException {
if (isClosed())
throw new SocketException("Socket is closed");
getImpl().setTTL(ttl);
}
/**
* Set the default time-to-live for multicast packets sent out
* on this {@code MulticastSocket} in order to control the
* scope of the multicasts.
*
* <P> The ttl <B>must</B> be in the range {@code 0 <= ttl <=
* 255} or an {@code IllegalArgumentException} will be thrown.
* Multicast packets sent with a TTL of {@code 0} are not transmitted
* on the network but may be delivered locally.
*
* @param ttl
* the time-to-live
*
* @throws IOException
* if an I/O exception occurs while setting the
* default time-to-live value
*
* @see #getTimeToLive()
*/
public void setTimeToLive(int ttl) throws IOException {
if (ttl < 0 || ttl > 255) {
throw new IllegalArgumentException("ttl out of range");
}
if (isClosed())
throw new SocketException("Socket is closed");
getImpl().setTimeToLive(ttl);
}
/**
* Get the default time-to-live for multicast packets sent out on
* the socket.
*
* @throws IOException if an I/O exception occurs
* while getting the default time-to-live value
* @return the default time-to-live value
* @deprecated use the getTimeToLive method instead, which returns
* an <b>int</b> instead of a <b>byte</b>.
* @see #setTTL(byte)
*/
@Deprecated
public byte getTTL() throws IOException {
if (isClosed())
throw new SocketException("Socket is closed");
return getImpl().getTTL();
}
/**
* Get the default time-to-live for multicast packets sent out on
* the socket.
* @throws IOException if an I/O exception occurs while
* getting the default time-to-live value
* @return the default time-to-live value
* @see #setTimeToLive(int)
*/
public int getTimeToLive() throws IOException {
if (isClosed())
throw new SocketException("Socket is closed");
return getImpl().getTimeToLive();
}
/**
* Joins a multicast group. Its behavior may be affected by
* {@code setInterface} or {@code setNetworkInterface}.
*
* <p>If there is a security manager, this method first
* calls its {@code checkMulticast} method with the
* {@code mcastaddr} argument as its argument.
*
* @param mcastaddr is the multicast address to join
* @throws IOException if there is an error joining,
* or when the address is not a multicast address,
* or the platform does not support multicasting
* @throws SecurityException if a security manager exists and its
* {@code checkMulticast} method doesn't allow the join.
* @deprecated This method does not accept the network interface on
* which to join the multicast group. Use
* {@link #joinGroup(SocketAddress, NetworkInterface)} instead.
* @see SecurityManager#checkMulticast(InetAddress)
*/
@Deprecated(since="14")
public void joinGroup(InetAddress mcastaddr) throws IOException {
if (isClosed()) {
throw new SocketException("Socket is closed");
}
checkAddress(mcastaddr, "joinGroup");
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkMulticast(mcastaddr);
}
if (!mcastaddr.isMulticastAddress()) {
throw new SocketException("Not a multicast address");
}
/**
* required for some platforms where it's not possible to join
* a group without setting the interface first.
*/
NetworkInterface defaultInterface = NetworkInterface.getDefault();
if (!interfaceSet && defaultInterface != null) {
setNetworkInterface(defaultInterface);
}
getImpl().join(mcastaddr);
}
/**
* Leave a multicast group. Its behavior may be affected by
* {@code setInterface} or {@code setNetworkInterface}.
*
* <p>If there is a security manager, this method first
* calls its {@code checkMulticast} method with the
* {@code mcastaddr} argument as its argument.
*
* @param mcastaddr is the multicast address to leave
* @throws IOException if there is an error leaving
* or when the address is not a multicast address.
* @throws SecurityException if a security manager exists and its
* {@code checkMulticast} method doesn't allow the operation.
* @deprecated This method does not accept the network interface on which
* to leave the multicast group. Use
* {@link #leaveGroup(SocketAddress, NetworkInterface)} instead.
* @see SecurityManager#checkMulticast(InetAddress)
*/
@Deprecated(since="14")
public void leaveGroup(InetAddress mcastaddr) throws IOException {
if (isClosed()) {
throw new SocketException("Socket is closed");
}
checkAddress(mcastaddr, "leaveGroup");
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkMulticast(mcastaddr);
}
if (!mcastaddr.isMulticastAddress()) {
throw new SocketException("Not a multicast address");
}
getImpl().leave(mcastaddr);
}
/**
* Joins the specified multicast group at the specified interface.
*
* <p>If there is a security manager, this method first
* calls its {@code checkMulticast} method
* with the {@code mcastaddr} argument
* as its argument.
*
* @param mcastaddr is the multicast address to join
* @param netIf specifies the local interface to receive multicast
* datagram packets, or {@code null} to defer to the interface set by
* {@link MulticastSocket#setInterface(InetAddress)} or
* {@link MulticastSocket#setNetworkInterface(NetworkInterface)}.
* If {@code null}, and no interface has been set, the behaviour is
* unspecified: any interface may be selected or the operation may fail
* with a {@code SocketException}.
* @throws IOException if there is an error joining, or when the address
* is not a multicast address, or the platform does not support
* multicasting
* @throws SecurityException if a security manager exists and its
* {@code checkMulticast} method doesn't allow the join.
* @throws IllegalArgumentException if mcastaddr is {@code null} or is a
* SocketAddress subclass not supported by this socket
* @see SecurityManager#checkMulticast(InetAddress)
* @since 1.4
*/
public void joinGroup(SocketAddress mcastaddr, NetworkInterface netIf)
throws IOException {
if (isClosed())
throw new SocketException("Socket is closed");
if (mcastaddr == null || !(mcastaddr instanceof InetSocketAddress))
throw new IllegalArgumentException("Unsupported address type");
if (oldImpl)
throw new UnsupportedOperationException();
checkAddress(((InetSocketAddress)mcastaddr).getAddress(), "joinGroup");
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkMulticast(((InetSocketAddress)mcastaddr).getAddress());
}
if (!((InetSocketAddress)mcastaddr).getAddress().isMulticastAddress()) {
throw new SocketException("Not a multicast address");
}
getImpl().joinGroup(mcastaddr, netIf);
}
/**
* Leave a multicast group on a specified local interface.
*
* <p>If there is a security manager, this method first
* calls its {@code checkMulticast} method with the
* {@code mcastaddr} argument as its argument.
*
* @param mcastaddr is the multicast address to leave
* @param netIf specifies the local interface or {@code null} to defer
* to the interface set by
* {@link MulticastSocket#setInterface(InetAddress)} or
* {@link MulticastSocket#setNetworkInterface(NetworkInterface)}.
* If {@code null}, and no interface has been set, the behaviour
* is unspecified: any interface may be selected or the operation
* may fail with a {@code SocketException}.
* @throws IOException if there is an error leaving or when the address
* is not a multicast address.
* @throws SecurityException if a security manager exists and its
* {@code checkMulticast} method doesn't allow the operation.
* @throws IllegalArgumentException if mcastaddr is {@code null} or is a
* SocketAddress subclass not supported by this socket.
* @see SecurityManager#checkMulticast(InetAddress)
* @since 1.4
*/
public void leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf)
throws IOException {
if (isClosed())
throw new SocketException("Socket is closed");
if (mcastaddr == null || !(mcastaddr instanceof InetSocketAddress))
throw new IllegalArgumentException("Unsupported address type");
if (oldImpl)
throw new UnsupportedOperationException();
checkAddress(((InetSocketAddress)mcastaddr).getAddress(), "leaveGroup");
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkMulticast(((InetSocketAddress)mcastaddr).getAddress());
}
if (!((InetSocketAddress)mcastaddr).getAddress().isMulticastAddress()) {
throw new SocketException("Not a multicast address");
}
getImpl().leaveGroup(mcastaddr, netIf);
}
/**
* Set the multicast network interface used by methods
* whose behavior would be affected by the value of the
* network interface. Useful for multihomed hosts.
*
* @param inf the InetAddress
* @throws SocketException if there is an error in
* the underlying protocol, such as a TCP error.
* @deprecated The InetAddress may not uniquely identify
* the network interface. Use
* {@link #setNetworkInterface(NetworkInterface)} instead.
* @see #getInterface()
*/
@Deprecated(since="14")
public void setInterface(InetAddress inf) throws SocketException {
if (isClosed()) {
throw new SocketException("Socket is closed");
}
checkAddress(inf, "setInterface");
synchronized (infLock) {
getImpl().setOption(SocketOptions.IP_MULTICAST_IF, inf);
infAddress = inf;
interfaceSet = true;
}
}
/**
* Retrieve the address of the network interface used for
* multicast packets.
*
* @return An {@code InetAddress} representing the address
* of the network interface used for multicast packets,
* or if no interface has been set, an {@code InetAddress}
* representing any local address.
* @throws SocketException if there is an error in the
* underlying protocol, such as a TCP error.
* @deprecated The network interface may not be uniquely identified by
* the InetAddress returned.
* Use {@link #getNetworkInterface()} instead.
* @see #setInterface(java.net.InetAddress)
*/
@Deprecated(since="14")
public InetAddress getInterface() throws SocketException {
if (isClosed()) {
throw new SocketException("Socket is closed");
}
synchronized (infLock) {
InetAddress ia =
(InetAddress)getImpl().getOption(SocketOptions.IP_MULTICAST_IF);
/**
* No previous setInterface or interface can be
* set using setNetworkInterface
*/
if (infAddress == null) {
return ia;
}
/**
* Same interface set with setInterface?
*/
if (ia.equals(infAddress)) {
return ia;
}
/**
* Different InetAddress from what we set with setInterface
* so enumerate the current interface to see if the
* address set by setInterface is bound to this interface.
*/
try {
NetworkInterface ni = NetworkInterface.getByInetAddress(ia);
Enumeration<InetAddress> addrs = ni.getInetAddresses();
while (addrs.hasMoreElements()) {
InetAddress addr = addrs.nextElement();
if (addr.equals(infAddress)) {
return infAddress;
}
}
/**
* No match so reset infAddress to indicate that the
* interface has changed via means
*/
infAddress = null;
return ia;
} catch (Exception e) {
return ia;
}
}
}
/**
* Specify the network interface for outgoing multicast datagrams
* sent on this socket.
*
* @param netIf the interface
* @throws SocketException if there is an error in
* the underlying protocol, such as a TCP error.
* @see #getNetworkInterface()
* @since 1.4
*/
public void setNetworkInterface(NetworkInterface netIf)
throws SocketException {
synchronized (infLock) {
getImpl().setOption(SocketOptions.IP_MULTICAST_IF2, netIf);
infAddress = null;
interfaceSet = true;
}
}
/**
* Get the multicast network interface set.
*
* @throws SocketException if there is an error in
* the underlying protocol, such as a TCP error.
* @return The multicast {@code NetworkInterface} currently set. A placeholder
* NetworkInterface is returned when there is no interface set; it has
* a single InetAddress to represent any local address.
* @see #setNetworkInterface(NetworkInterface)
* @since 1.4
*/
public NetworkInterface getNetworkInterface() throws SocketException {
NetworkInterface ni
= (NetworkInterface)getImpl().getOption(SocketOptions.IP_MULTICAST_IF2);
if (ni == null) {
InetAddress[] addrs = new InetAddress[1];
addrs[0] = InetAddress.anyLocalAddress();
return new NetworkInterface(addrs[0].getHostName(), 0, addrs);
} else {
return ni;
}
}
/**
* Disable/Enable local loopback of multicast datagrams
* The option is used by the platform's networking code as a hint
* for setting whether multicast data will be looped back to
* the local socket.
*
* <p>Because this option is a hint, applications that want to
* verify what loopback mode is set to should call
* {@link #getLoopbackMode()}
* @param disable {@code true} to disable the LoopbackMode
* @throws SocketException if an error occurs while setting the value
* @since 1.4
* @deprecated Use {@link #setOption(SocketOption, Object)} with
* {@link java.net.StandardSocketOptions#IP_MULTICAST_LOOP}
* instead. The loopback mode is enabled by default,
* {@code MulticastSocket.setOption(StandardSocketOptions.IP_MULTICAST_LOOP, false)}
* disables it.
* @see #getLoopbackMode
*/
@Deprecated(since="14")
public void setLoopbackMode(boolean disable) throws SocketException {
getImpl().setOption(SocketOptions.IP_MULTICAST_LOOP, Boolean.valueOf(disable));
}
/**
* Get the setting for local loopback of multicast datagrams.
*
* @throws SocketException if an error occurs while getting the value
* @return true if the LoopbackMode has been disabled
* @since 1.4
* @deprecated Use {@link #getOption(SocketOption)} with
* {@link java.net.StandardSocketOptions#IP_MULTICAST_LOOP}
* instead.
* @see #setLoopbackMode
*/
@Deprecated(since="14")
public boolean getLoopbackMode() throws SocketException {
return ((Boolean)getImpl().getOption(SocketOptions.IP_MULTICAST_LOOP)).booleanValue();
}
/**
* Sends a datagram packet to the destination, with a TTL (time-
* to-live) other than the default for the socket. This method
* need only be used in instances where a particular TTL is desired;
* otherwise it is preferable to set a TTL once on the socket, and
* use that default TTL for all packets. This method does <B>not
* </B> alter the default TTL for the socket. Its behavior may be
* affected by {@code setInterface}.
*
* <p>If there is a security manager, this method first performs some
* security checks. First, if {@code p.getAddress().isMulticastAddress()}
* is true, this method calls the
* security manager's {@code checkMulticast} method
* with {@code p.getAddress()} and {@code ttl} as its arguments.
* If the evaluation of that expression is false,
* this method instead calls the security manager's
* {@code checkConnect} method with arguments
* {@code p.getAddress().getHostAddress()} and
* {@code p.getPort()}. Each call to a security manager method
* could result in a SecurityException if the operation is not allowed.
*
* @param p is the packet to be sent. The packet should contain
* the destination multicast ip address and the data to be sent.
* One does not need to be the member of the group to send
* packets to a destination multicast address.
* @param ttl optional time to live for multicast packet.
* default ttl is 1.
*
* @throws IOException is raised if an error occurs i.e
* error while setting ttl.
* @throws SecurityException if a security manager exists and its
* {@code checkMulticast} or {@code checkConnect}
* method doesn't allow the send.
* @throws PortUnreachableException may be thrown if the socket is connected
* to a currently unreachable destination. Note, there is no
* guarantee that the exception will be thrown.
* @throws IllegalArgumentException if the socket is connected,
* and connected address and packet address differ, or
* if the socket is not connected and the packet address
* is not set.
*
*
* @deprecated Use the following code or its equivalent instead:
* ......
* int ttl = mcastSocket.getTimeToLive();
* mcastSocket.setTimeToLive(newttl);
* mcastSocket.send(p);
* mcastSocket.setTimeToLive(ttl);
* ......
*
* @see DatagramSocket#send
* @see DatagramSocket#receive
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