java.net.ServerSocket
is new.
java.lang.Object
This class implements server sockets. A server socket waits for requests to come in over the network. It performs some operation based on that request, and then possibly returns a result to the requester.
The actual work of the server socket is performed by an instance of the SocketImpl class. An application can change the socket factory that creates the socket implementation to configure itself to create sockets appropriate to the local firewall.
| Constructor Summary | |
|---|---|
|
ServerSocket
() Creates an unbound server socket. |
|
|
ServerSocket
(int port) Creates a server socket, bound to the specified port. |
|
|
ServerSocket
(int port, int backlog) Creates a server socket and binds it to the specified local port number, with the specified backlog. |
|
|
ServerSocket
(int port, int backlog,
InetAddress
bindAddr) Create a server with the specified port, listen backlog, and local IP address to bind to. |
|
|
ServerSocket
(
Proxy
Creates an unbound server socket, specifying the type of proxy, if any, that should be used regardless of any other settings.
|
|
| Method Summary | |
|---|---|
| Socket |
accept
() Listens for a connection to be made to this socket and accepts it. |
| void |
bind
(
SocketAddress
endpoint) Binds the ServerSocket to a specific address (IP address and port number). |
| void |
bind
(
SocketAddress
endpoint, int backlog) Binds the ServerSocket to a specific address (IP address and port number). |
| void |
close
() Closes this socket. |
| ServerSocketChannel |
getChannel
() Returns the unique ServerSocketChannel object associated with this socket, if any. |
| InetAddress |
getInetAddress
() Returns the local address of this server socket. |
| int |
getLocalPort
() Returns the port on which this socket is listening. |
| SocketAddress |
getLocalSocketAddress
() Returns the address of the endpoint this socket is bound to, or null if it is not bound yet. |
| int |
getReceiveBufferSize
() Gets the value of the SO_RCVBUF option for this ServerSocket , that is the proposed buffer size that will be used for Sockets accepted from this ServerSocket . |
| boolean |
getReuseAddress
() Tests if SO_REUSEADDR is enabled. |
| int |
getSoTimeout
() Retrive setting for SO_TIMEOUT. |
| protected void |
implAccept
(
Socket
s) Subclasses of ServerSocket use this method to override accept() to return their own subclass of socket. |
| boolean |
isBound
() Returns the binding state of the ServerSocket. |
| boolean |
isClosed
() Returns the closed state of the ServerSocket. |
| void |
setReceiveBufferSize
(int size) Sets a default proposed value for the SO_RCVBUF option for sockets accepted from this ServerSocket . |
| void |
setReuseAddress
(boolean on) Enable/disable the SO_REUSEADDR socket option. |
| static void |
setSocketFactory
(
SocketImplFactory
fac) Sets the server socket implementation factory for the application. |
| void |
setSoTimeout
(int timeout) Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. |
| String |
toString
() Returns the implementation address and implementation port of this socket as a String. |
| Methods inherited from class java.lang. Object |
|---|
| clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait |
| Constructor Detail |
|---|
public ServerSocket()
throws IOException
ServerSocket
Creates an unbound server socket, specifying the type of proxy, if any, that should be used regardless of any other settings.
If there is a security manager, its checkConnect method is called with the proxy host address and port number as its arguments. This could result in a SecurityException.
Examples:
ServerSocket s = new ServerSocket(Proxy.NO_PROXY); will create a plain server socket ignoring any other proxy configuration.
ServerSocket s = new ServerSocket(new Proxy(Proxy.Type.SOCKS, new InetSocketAddress("socks.mydom.com", 1080))); will create a socket accepting connections through the specified SOCKS proxy server.
Parameters:
proxy - a
Proxy
object specifying what kind of proxying should be used.
Throws:
IllegalArgumentException
- if the proxy is of an invalid type or is null.
SecurityException
- if a security manager is present and permission to connect to the proxy is denied.
Since:
1.5
See Also:
ProxySelector
,
Proxy
public ServerSocket(int port)
throws IOException
The maximum queue length for incoming connection indications (a request to connect) is set to 50. If a connection indication arrives when the queue is full, the connection is refused.
If the application has specified a server socket factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a "plain" socket is created.
If there is a security manager, its checkListen method is called with the port argument as its argument to ensure the operation is allowed. This could result in a SecurityException.
public ServerSocket(int port,
int backlog)
throws IOException
The maximum queue length for incoming connection indications (a request to connect) is set to the backlog parameter. If a connection indication arrives when the queue is full, the connection is refused.
If the application has specified a server socket factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a "plain" socket is created.
If there is a security manager, its checkListen method is called with the port argument as its argument to ensure the operation is allowed. This could result in a SecurityException.
The backlog argument must be a positive value greater than 0. If the value passed if equal or less than 0, then the default value will be assumed.
public ServerSocket(int port,
int backlog,
InetAddress bindAddr)
throws IOException
If there is a security manager, this method calls its checkListen method with the port argument as its argument to ensure the operation is allowed. This could result in a SecurityException.
The backlog argument must be a positive value greater than 0. If the value passed if equal or less than 0, then the default value will be assumed.
| Method Detail |
|---|
public void bind(SocketAddress endpoint)
throws IOException
If the address is null, then the system will pick up an ephemeral port and a valid local address to bind the socket.
public void bind(SocketAddress endpoint,
int backlog)
throws IOException
If the address is null, then the system will pick up an ephemeral port and a valid local address to bind the socket.
The backlog argument must be a positive value greater than 0. If the value passed if equal or less than 0, then the default value will be assumed.
public InetAddress getInetAddress()
public int getLocalPort()
public SocketAddress getLocalSocketAddress()
public Socket accept()
throws IOException
A new Socket s is created and, if there is a security manager, the security manager's checkAccept method is called with s.getInetAddress().getHostAddress() and s.getPort() as its arguments to ensure the operation is allowed. This could result in a SecurityException.
protected final void implAccept(Socket s)
throws IOException
public void close()
throws IOException
If this socket has an associated channel then the channel is closed as well.
public ServerSocketChannel getChannel()
A server socket will have a channel if, and only if, the channel itself was created via the ServerSocketChannel.open method.
public boolean isBound()
public boolean isClosed()
public void setSoTimeout(int timeout)
throws SocketException
public int getSoTimeout()
throws IOException
public void setReuseAddress(boolean on)
throws SocketException
When a TCP connection is closed the connection may remain in a timeout state for a period of time after the connection is closed (typically known as the TIME_WAIT state or 2MSL wait state). For applications using a well known socket address or port it may not be possible to bind a socket to the required SocketAddress if there is a connection in the timeout state involving the socket address or port.
Enabling SO_REUSEADDR prior to binding the socket using bind(SocketAddress) allows the socket to be bound even though a previous connection is in a timeout state.
When a ServerSocket is created the initial setting of SO_REUSEADDR is not defined. Applications can use getReuseAddress() to determine the initial setting of SO_REUSEADDR .
The behaviour when SO_REUSEADDR is enabled or disabled after a socket is bound (See isBound() ) is not defined.
public boolean getReuseAddress()
throws SocketException
public String toString()
public static void setSocketFactory(SocketImplFactory fac)
throws IOException
When an application creates a new server socket, the socket implementation factory's createSocketImpl method is called to create the actual socket implementation.
If there is a security manager, this method first calls the security manager's checkSetFactory method to ensure the operation is allowed. This could result in a SecurityException.
public void setReceiveBufferSize(int size)
throws SocketException
The value of SO_RCVBUF is used both to set the size of the internal socket receive buffer, and to set the size of the TCP receive window that is advertized to the remote peer.
It is possible to change the value subsequently, by calling Socket.setReceiveBufferSize(int) . However, if the application wishes to allow a receive window larger than 64K bytes, as defined by RFC1323 then the proposed value must be set in the ServerSocket before it is bound to a local address. This implies, that the ServerSocket must be created with the no-argument constructor, then setReceiveBufferSize() must be called and lastly the ServerSocket is bound to an address by calling bind().
Failure to do this will not cause an error, and the buffer size may be set to the requested value but the TCP receive window in sockets accepted from this ServerSocket will be no larger than 64K bytes.
public int getReceiveBufferSize()
throws SocketException
Note, the value actually set in the accepted socket is determined by calling Socket.getReceiveBufferSize() .