Class Socket

public Socket()

Initializes a new instance of Socket object without connecting to a remote host. This useful for subclasses of socket that might want this behavior.

Since:

1.1

public Socket(String host,
              int port)
            throws UnknownHostException,
                   IOException

Initializes a new instance of Socket and connects to the hostname and port specified as arguments.

Parameters:

host - The name of the host to connect to

port - The port number to connect to

Throws:

UnknownHostException - If the hostname cannot be resolved to a network address.

IOException - If an error occurs

SecurityException - If a security manager exists and its checkConnect method doesn't allow the operation

public Socket(String host,
              int port,
              boolean stream)
            throws IOException

Deprecated. Use the DatagramSocket class to create datagram oriented sockets.

Initializes a new instance of Socket and connects to the hostname and port specified as arguments. If the stream argument is set to true, then a stream socket is created. If it is false, a datagram socket is created.

Parameters:

host - The name of the host to connect to

port - The port to connect to

stream - true for a stream socket, false for a datagram socket

Throws:

IOException - If an error occurs

SecurityException - If a security manager exists and its checkConnect method doesn't allow the operation

public Socket(String host,
              int port,
              InetAddress localAddr,
              int localPort)
            throws IOException

Initializes a new instance of Socket that connects to the named host on the specified port and binds to the specified local address and port.

Parameters:

host - The name of the remote host to connect to.

port - The remote port to connect to.

localAddr - The local address to bind to.

localPort - The local port to bind to.

Throws:

SecurityException - If the SecurityManager exists and does not allow a connection to the specified host/port or binding to the specified local host/port.

IOException - If a connection error occurs.

Since:

1.1

public Socket(InetAddress address,
              int port)
            throws IOException

Initializes a new instance of Socket and connects to the address and port number specified as arguments.

Parameters:

address - The address to connect to

port - The port number to connect to

Throws:

IOException - If an error occurs

SecurityException - If a security manager exists and its checkConnect method doesn't allow the operation

public Socket(InetAddress host,
              int port,
              boolean stream)
            throws IOException

Deprecated. Use the DatagramSocket class to create datagram oriented sockets.

Initializes a new instance of Socket and connects to the address and port number specified as arguments. If the stream param is true, a stream socket will be created, otherwise a datagram socket is created.

Parameters:

host - The address to connect to

port - The port number to connect to

stream - true to create a stream socket, false to create a datagram socket.

Throws:

IOException - If an error occurs

SecurityException - If a security manager exists and its checkConnect method doesn't allow the operation

public Socket(InetAddress address,
              int port,
              InetAddress localAddr,
              int localPort)
            throws IOException

Initializes a new instance of Socket and connects to the address and port number specified as arguments, plus binds to the specified local address and port.

Parameters:

address - The remote address to connect to

port - The remote port to connect to

localAddr - The local address to connect to

localPort - The local port to connect to

Throws:

IOException - If an error occurs

SecurityException - If a security manager exists and its checkConnect method doesn't allow the operation

Since:

1.1

protected Socket(SocketImpl impl)
            throws SocketException

Initializes a new instance of Socket object without connecting to a remote host. This is useful for subclasses of socket that might want this behavior.

Additionally, this socket will be created using the supplied implementation class instead the default class or one returned by a factory. If this value is null, the default Socket implementation is used.

Parameters:

impl - The SocketImpl to use for this Socket

Throws:

SocketException - If an error occurs

Since:

1.1

public void bind(SocketAddress bindpoint)
            throws IOException

Binds the socket to the given local address/port

Parameters:

bindpoint - The address/port to bind to

Throws:

IOException - If an error occurs

SecurityException - If a security manager exists and its checkConnect method doesn't allow the operation

IllegalArgumentException - If the address type is not supported

Since:

1.4

public void close()
            throws IOException

Closes the socket.

Throws:

IOException - If an error occurs

public void connect(SocketAddress endpoint)
            throws IOException

Connects the socket with a remote address.

Parameters:

endpoint - The address to connect to

Throws:

IOException - If an error occurs

IllegalArgumentException - If the addess type is not supported

IllegalBlockingModeException - If this socket has an associated channel, and the channel is in non-blocking mode

Since:

1.4

public void connect(SocketAddress endpoint,
                    int timeout)
            throws IOException

Connects the socket with a remote address. A timeout of zero is interpreted as an infinite timeout. The connection will then block until established or an error occurs.

Parameters:

endpoint - The address to connect to

timeout - The length of the timeout in milliseconds, or 0 to indicate no timeout.

Throws:

IOException - If an error occurs

IllegalArgumentException - If the address type is not supported

IllegalBlockingModeException - If this socket has an associated channel, and the channel is in non-blocking mode

SecurityException - if the SocketAddress is an InetSocketAddress and a security manager is present which does not allow connections on the given host and port.

Since:

1.4

public SocketChannel getChannel()

Returns the socket channel associated with this socket.

Returns:

the associated socket channel, null if no associated channel exists

Since:

1.4

public InetAddress getInetAddress()

Returns the address of the remote end of the socket. If this socket is not connected, then null is returned.

Returns:

The remote address this socket is connected to

public InputStream getInputStream()
            throws IOException

Returns an InputStream for reading from this socket.

Returns:

The InputStream object

Throws:

IOException - If an error occurs or Socket is not connected

public boolean getKeepAlive()
            throws SocketException

This method returns the value of the socket level socket option SO_KEEPALIVE.

Returns:

The setting

Throws:

SocketException - If an error occurs or Socket is not connected

Since:

1.3

public InetAddress getLocalAddress()

Returns the local address to which this socket is bound. If this socket is not connected, then a wildcard address, for which

Returns:

The local address

Since:

1.1

See Also:

is true, is returned.

public int getLocalPort()

Returns the local port number to which this socket is bound. If this socket is not connected, then -1 is returned.

Returns:

The local port

public SocketAddress getLocalSocketAddress()

Returns local socket address.

Returns:

the local socket address, null if not bound

Since:

1.4

public boolean getOOBInline()
            throws SocketException

Returns the current setting of the SO_OOBINLINE option for this socket

Returns:

True if SO_OOBINLINE is set, false otherwise.

Throws:

SocketException - If an error occurs

Since:

1.4

public OutputStream getOutputStream()
            throws IOException

Returns an OutputStream for writing to this socket.

Returns:

The OutputStream object

Throws:

IOException - If an error occurs or Socket is not connected

public int getPort()

Returns the port number of the remote end of the socket connection. If this socket is not connected, then 0 is returned.

Returns:

The remote port this socket is connected to

public int getReceiveBufferSize()
            throws SocketException

This method returns the value of the system level socket option SO_RCVBUF, which is used by the operating system to tune buffer sizes for data transfers.

Returns:

The receive buffer size.

Throws:

SocketException - If an error occurs or Socket is not connected

Since:

1.2

public SocketAddress getRemoteSocketAddress()

Returns the remote socket address.

Returns:

the remote socket address, null of not connected

Since:

1.4

public boolean getReuseAddress()
            throws SocketException

Checks if the SO_REUSEADDR option is enabled

Returns:

True if SO_REUSEADDR is set, false otherwise.

Throws:

SocketException - If an error occurs

Since:

1.4

public int getSendBufferSize()
            throws SocketException

This method returns the value of the system level socket option SO_SNDBUF, which is used by the operating system to tune buffer sizes for data transfers.

Returns:

The send buffer size.

Throws:

SocketException - If an error occurs or socket not connected

Since:

1.2

public int getSoLinger()
            throws SocketException

Returns the value of the SO_LINGER option on the socket. If the SO_LINGER option is set on a socket and there is still data waiting to be sent when the socket is closed, then the close operation will block until either that data is delivered or until the timeout period expires. This method either returns the timeouts (in hundredths of of a second (platform specific?)) if SO_LINGER is set, or -1 if SO_LINGER is not set.

Returns:

The SO_LINGER timeout in hundreths of a second or -1 if SO_LINGER not set

Throws:

SocketException - If an error occurs or Socket is not connected

Since:

1.1

public int getSoTimeout()
            throws SocketException

Returns the value of the SO_TIMEOUT option on the socket. If this value is set, and an read/write is performed that does not complete within the timeout period, a short count is returned (or an EWOULDBLOCK signal would be sent in Unix if no data had been read). A value of 0 for this option implies that there is no timeout (ie, operations will block forever). On systems that have separate read and write timeout values, this method returns the read timeout. This value is in thousandths of a second (implementation specific?).

Returns:

The length of the timeout in thousandth's of a second or 0 if not set

Throws:

SocketException - If an error occurs or Socket not connected

Since:

1.1

public boolean getTcpNoDelay()
            throws SocketException

Tests whether or not the TCP_NODELAY option is set on the socket. Returns true if enabled, false if disabled. When on it disables the Nagle algorithm which means that packets are always send immediatly and never merged together to reduce network trafic.

Returns:

Whether or not TCP_NODELAY is set

Throws:

SocketException - If an error occurs or Socket not connected

Since:

1.1

public int getTrafficClass()
            throws SocketException

Returns the current traffic class

Returns:

The current traffic class.

Throws:

SocketException - If an error occurs

Since:

1.4

See Also:

Socket.setTrafficClass(int tc)

public boolean isBound()

Checks if the socket is already bound.

Returns:

True if socket is bound, false otherwise.

Since:

1.4

public boolean isClosed()

Checks if the socket is closed.

Returns:

True if socket is closed, false otherwise.

Since:

1.4

public boolean isConnected()

Checks if the socket is connected

Returns:

True if socket is connected, false otherwise.

Since:

1.4

public boolean isInputShutdown()

Checks if the socket's input stream is shutdown

Returns:

True if input is shut down.

Since:

1.4

public boolean isOutputShutdown()

Checks if the socket's output stream is shutdown

Returns:

True if output is shut down.

Since:

1.4

public void sendUrgentData(int data)
            throws IOException

Sends urgent data through the socket

Parameters:

data - The data to send. Only the lowest eight bits of data are sent

Throws:

IOException - If an error occurs

Since:

1.4

public void setKeepAlive(boolean on)
            throws SocketException

This method sets the value for the socket level socket option SO_KEEPALIVE.

Parameters:

on - True if SO_KEEPALIVE should be enabled

Throws:

SocketException - If an error occurs or Socket is not connected

Since:

1.3

public void setOOBInline(boolean on)
            throws SocketException

Enables/disables the SO_OOBINLINE option

Parameters:

on - True if SO_OOBLINE should be enabled

Throws:

SocketException - If an error occurs

Since:

1.4

public void setReceiveBufferSize(int size)
            throws SocketException

This method sets the value for the system level socket option SO_RCVBUF to the specified value. Note that valid values for this option are specific to a given operating system.

Parameters:

size - The new receive buffer size.

Throws:

SocketException - If an error occurs or Socket is not connected

IllegalArgumentException - If size is 0 or negative

Since:

1.2

public void setReuseAddress(boolean reuseAddress)
            throws SocketException

Enables/Disables the SO_REUSEADDR option

Parameters:

reuseAddress - true if SO_REUSEADDR should be enabled, false otherwise

Throws:

SocketException - If an error occurs

Since:

1.4

public void setSendBufferSize(int size)
            throws SocketException

This method sets the value for the system level socket option SO_SNDBUF to the specified value. Note that valid values for this option are specific to a given operating system.

Parameters:

size - The new send buffer size.

Throws:

SocketException - If an error occurs or Socket not connected

IllegalArgumentException - If size is 0 or negative

Since:

1.2

public void setSoLinger(boolean on,
                        int linger)
            throws SocketException

Sets the value of the SO_LINGER option on the socket. If the SO_LINGER option is set on a socket and there is still data waiting to be sent when the socket is closed, then the close operation will block until either that data is delivered or until the timeout period expires. The linger interval is specified in hundreths of a second (platform specific?)

Parameters:

on - true to enable SO_LINGER, false to disable

linger - The SO_LINGER timeout in hundreths of a second or -1 if SO_LINGER not set.

Throws:

SocketException - If an error occurs or Socket not connected

IllegalArgumentException - If linger is negative

Since:

1.1

public void setSoTimeout(int timeout)
            throws SocketException

Sets the value of the SO_TIMEOUT option on the socket. If this value is set, and an read/write is performed that does not complete within the timeout period, a short count is returned (or an EWOULDBLOCK signal would be sent in Unix if no data had been read). A value of 0 for this option implies that there is no timeout (ie, operations will block forever). On systems that have separate read and write timeout values, this method returns the read timeout. This value is in milliseconds.

Parameters:

timeout - The length of the timeout in milliseconds, or 0 to indicate no timeout.

Throws:

SocketException - If an error occurs or Socket not connected

Since:

1.1

public static void setSocketImplFactory(SocketImplFactory fac)
            throws IOException

Sets the SocketImplFactory. This may be done only once per virtual machine. Subsequent attempts will generate a SocketException. Note that a SecurityManager check is made prior to setting the factory. If insufficient privileges exist to set the factory, then an IOException will be thrown.

Parameters:

fac - the factory to set

Throws:

SecurityException - If the SecurityManager does not allow this operation.

IOException - If any other error occurs

public void setTcpNoDelay(boolean on)
            throws SocketException

Sets the TCP_NODELAY option on the socket.

Parameters:

on - true to enable, false to disable

Throws:

SocketException - If an error occurs or Socket is not connected

Since:

1.1

public void setTrafficClass(int tc)
            throws SocketException

Sets the traffic class value

Parameters:

tc - The traffic class

Throws:

SocketException - If an error occurs

IllegalArgumentException - If tc value is illegal

Since:

1.4

See Also:

getTrafficClass()

public void shutdownInput()
            throws IOException

Closes the input side of the socket stream.

Throws:

IOException - If an error occurs.

Since:

1.3

public void shutdownOutput()
            throws IOException

Closes the output side of the socket stream.

Throws:

IOException - If an error occurs.

Since:

1.3

public String toString()

Converts this Socket to a String.

Overrides:

toString in interface Object

Returns:

The String representation of this Socket