Package java.net

Class Socket

java.lang.Object
java.net.Socket
All Implemented Interfaces:
Closeable, AutoCloseable
Direct Known Subclasses:
SSLSocket
public class Socket
extends Object
implements Closeable
Provides a client-side TCP socket.

  • Constructor Details

    • Socket

      public Socket()
      Creates a new unconnected socket. When a SocketImplFactory is defined it creates the internal socket implementation, otherwise the default socket implementation will be used for this socket.
      See Also:
      SocketImplFactory, SocketImpl

    • Socket

      public Socket​(Proxy proxy)
      Creates a new unconnected socket using the given proxy type. When a SocketImplFactory is defined it creates the internal socket implementation, otherwise the default socket implementation will be used for this socket.

      Example that will create a socket connection through a SOCKS proxy server:
      Socket sock = new Socket(new Proxy(Proxy.Type.SOCKS, new InetSocketAddress("test.domain.org", 2130)));

      Parameters:
      proxy - the specified proxy for this socket.
      Throws:
      IllegalArgumentException - if the argument proxy is null or of an invalid type.
      See Also:
      SocketImplFactory, SocketImpl

    • Socket

      public Socket​(String dstName, int dstPort) throws UnknownHostException, IOException
      Creates a new streaming socket connected to the target host specified by the parameters dstName and dstPort. The socket is bound to any available port on the local host.

      This implementation tries each IP address for the given hostname (in RFC 3484 order) until it either connects successfully or it exhausts the set.

      Parameters:
      dstName - the target host name or IP address to connect to.
      dstPort - the port on the target host to connect to.
      Throws:
      UnknownHostException - if the host name could not be resolved into an IP address.
      IOException - if an error occurs while creating the socket.

    • Socket

      public Socket​(String dstName, int dstPort, InetAddress localAddress, int localPort) throws IOException
      Creates a new streaming socket connected to the target host specified by the parameters dstName and dstPort. On the local endpoint the socket is bound to the given address localAddress on port localPort. If host is null a loopback address is used to connect to.

      This implementation tries each IP address for the given hostname (in RFC 3484 order) until it either connects successfully or it exhausts the set.

      Parameters:
      dstName - the target host name or IP address to connect to.
      dstPort - the port on the target host to connect to.
      localAddress - the address on the local host to bind to.
      localPort - the port on the local host to bind to.
      Throws:
      UnknownHostException - if the host name could not be resolved into an IP address.
      IOException - if an error occurs while creating the socket.

    • Socket

      @Deprecated public Socket​(String hostName, int port, boolean streaming) throws IOException
      Deprecated.
      Use Socket(String, int) instead of this for streaming sockets or an appropriate constructor of DatagramSocket for UDP transport.
      Creates a new streaming or datagram socket connected to the target host specified by the parameters hostName and port. The socket is bound to any available port on the local host.

      This implementation tries each IP address for the given hostname (in RFC 3484 order) until it either connects successfully or it exhausts the set.

      Parameters:
      hostName - the target host name or IP address to connect to.
      port - the port on the target host to connect to.
      streaming - if true a streaming socket is returned, a datagram socket otherwise.
      Throws:
      UnknownHostException - if the host name could not be resolved into an IP address.
      IOException - if an error occurs while creating the socket.

    • Socket

      public Socket​(InetAddress dstAddress, int dstPort) throws IOException
      Creates a new streaming socket connected to the target host specified by the parameters dstAddress and dstPort. The socket is bound to any available port on the local host.
      Parameters:
      dstAddress - the target host address to connect to.
      dstPort - the port on the target host to connect to.
      Throws:
      IOException - if an error occurs while creating the socket.

    • Socket

      public Socket​(InetAddress dstAddress, int dstPort, InetAddress localAddress, int localPort) throws IOException
      Creates a new streaming socket connected to the target host specified by the parameters dstAddress and dstPort. On the local endpoint the socket is bound to the given address localAddress on port localPort.
      Parameters:
      dstAddress - the target host address to connect to.
      dstPort - the port on the target host to connect to.
      localAddress - the address on the local host to bind to.
      localPort - the port on the local host to bind to.
      Throws:
      IOException - if an error occurs while creating the socket.

    • Socket

      @Deprecated public Socket​(InetAddress addr, int port, boolean streaming) throws IOException
      Deprecated.
      Use Socket(InetAddress, int) instead of this for streaming sockets or an appropriate constructor of DatagramSocket for UDP transport.
      Creates a new streaming or datagram socket connected to the target host specified by the parameters addr and port. The socket is bound to any available port on the local host.
      Parameters:
      addr - the Internet address to connect to.
      port - the port on the target host to connect to.
      streaming - if true a streaming socket is returned, a datagram socket otherwise.
      Throws:
      IOException - if an error occurs while creating the socket.

    • Socket

      protected Socket​(SocketImpl impl) throws SocketException
      Creates an unconnected socket with the given socket implementation.
      Parameters:
      impl - the socket implementation to be used.
      Throws:
      SocketException - if an error occurs while creating the socket.

  • Method Details

    • close

      public void close() throws IOException
      Closes the socket. It is not possible to reconnect or rebind to this socket thereafter which means a new socket instance has to be created.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException - if an error occurs while closing the socket.

    • getInetAddress

      public InetAddress getInetAddress()
      Returns the IP address of the target host this socket is connected to, or null if this socket is not yet connected.

    • getInputStream

      public InputStream getInputStream() throws IOException
      Returns an input stream to read data from this socket.
      Returns:
      the byte-oriented input stream.
      Throws:
      IOException - if an error occurs while creating the input stream or the socket is in an invalid state.

    • getKeepAlive

      public boolean getKeepAlive() throws SocketException
      Returns this socket's SocketOptions.SO_KEEPALIVE setting.
      Throws:
      SocketException

    • getLocalAddress

      public InetAddress getLocalAddress()
      Returns the local IP address this socket is bound to, or InetAddress.ANY if the socket is unbound.

    • getLocalPort

      public int getLocalPort()
      Returns the local port this socket is bound to, or -1 if the socket is unbound.

    • getOutputStream

      public OutputStream getOutputStream() throws IOException
      Returns an output stream to write data into this socket.
      Returns:
      the byte-oriented output stream.
      Throws:
      IOException - if an error occurs while creating the output stream or the socket is in an invalid state.

    • getPort

      public int getPort()
      Returns the port number of the target host this socket is connected to, or 0 if this socket is not yet connected.

    • getSoLinger

      public int getSoLinger() throws SocketException
      Returns this socket's linger timeout in seconds, or -1 for no linger (i.e. close will return immediately).
      Throws:
      SocketException

    • getReceiveBufferSize

      public int getReceiveBufferSize() throws SocketException
      Returns this socket's receive buffer size.
      Throws:
      SocketException

    • getSendBufferSize

      public int getSendBufferSize() throws SocketException
      Returns this socket's send buffer size.
      Throws:
      SocketException

    • getSoTimeout

      public int getSoTimeout() throws SocketException
      Returns this socket's receive timeout.
      Throws:
      SocketException

    • getTcpNoDelay

      public boolean getTcpNoDelay() throws SocketException
      Returns this socket's SocketOptions#TCP_NODELAY setting.
      Throws:
      SocketException

    • setKeepAlive

      public void setKeepAlive​(boolean keepAlive) throws SocketException
      Sets this socket's SocketOptions.SO_KEEPALIVE option.
      Throws:
      SocketException

    • setSocketImplFactory

      public static void setSocketImplFactory​(SocketImplFactory fac) throws IOException
      Sets the internal factory for creating socket implementations. This may only be executed once during the lifetime of the application.
      Parameters:
      fac - the socket implementation factory to be set.
      Throws:
      IOException - if the factory has been already set.

    • setSendBufferSize

      public void setSendBufferSize​(int size) throws SocketException
      Sets this socket's send buffer size.
      Throws:
      SocketException

    • setReceiveBufferSize

      public void setReceiveBufferSize​(int size) throws SocketException
      Sets this socket's receive buffer size.
      Throws:
      SocketException

    • setSoLinger

      public void setSoLinger​(boolean on, int timeout) throws SocketException
      Sets this socket's linger timeout in seconds. If on is false, timeout is irrelevant.
      Throws:
      SocketException

    • setSoTimeout

      public void setSoTimeout​(int timeout) throws SocketException
      Sets this socket's read timeout in milliseconds. Use 0 for no timeout. To take effect, this option must be set before the blocking method was called.
      Throws:
      SocketException

    • setTcpNoDelay

      public void setTcpNoDelay​(boolean on) throws SocketException
      Sets this socket's SocketOptions.TCP_NODELAY option.
      Throws:
      SocketException

    • toString

      public String toString()
      Returns a String containing a concise, human-readable description of the socket.
      Overrides:
      toString in class Object
      Returns:
      the textual representation of this socket.

    • shutdownInput

      public void shutdownInput() throws IOException
      Closes the input stream of this socket. Any further data sent to this socket will be discarded. Reading from this socket after this method has been called will return the value EOF.
      Throws:
      IOException - if an error occurs while closing the socket input stream.
      SocketException - if the input stream is already closed.

    • shutdownOutput

      public void shutdownOutput() throws IOException
      Closes the output stream of this socket. All buffered data will be sent followed by the termination sequence. Writing to the closed output stream will cause an IOException.
      Throws:
      IOException - if an error occurs while closing the socket output stream.
      SocketException - if the output stream is already closed.

    • getLocalSocketAddress

      public SocketAddress getLocalSocketAddress()
      Returns the local address and port of this socket as a SocketAddress or null if the socket is unbound. This is useful on multihomed hosts.

    • getRemoteSocketAddress

      public SocketAddress getRemoteSocketAddress()
      Returns the remote address and port of this socket as a SocketAddress or null if the socket is not connected.
      Returns:
      the remote socket address and port.

    • isBound

      public boolean isBound()
      Returns whether this socket is bound to a local address and port.
      Returns:
      true if the socket is bound to a local address, false otherwise.

    • isConnected

      public boolean isConnected()
      Returns whether this socket is connected to a remote host.
      Returns:
      true if the socket is connected, false otherwise.

    • isClosed

      public boolean isClosed()
      Returns whether this socket is closed.
      Returns:
      true if the socket is closed, false otherwise.

    • bind

      public void bind​(SocketAddress localAddr) throws IOException
      Binds this socket to the given local host address and port specified by the SocketAddress localAddr. If localAddr is set to null, this socket will be bound to an available local address on any free port.
      Parameters:
      localAddr - the specific address and port on the local machine to bind to.
      Throws:
      IllegalArgumentException - if the given SocketAddress is invalid or not supported.
      IOException - if the socket is already bound or an error occurs while binding.

    • connect

      public void connect​(SocketAddress remoteAddr) throws IOException
      Connects this socket to the given remote host address and port specified by the SocketAddress remoteAddr.
      Parameters:
      remoteAddr - the address and port of the remote host to connect to.
      Throws:
      IllegalArgumentException - if the given SocketAddress is invalid or not supported.
      IOException - if the socket is already connected or an error occurs while connecting.

    • connect

      public void connect​(SocketAddress remoteAddr, int timeout) throws IOException
      Connects this socket to the given remote host address and port specified by the SocketAddress remoteAddr with the specified timeout. The connecting method will block until the connection is established or an error occurred.
      Parameters:
      remoteAddr - the address and port of the remote host to connect to.
      timeout - the timeout value in milliseconds or 0 for an infinite timeout.
      Throws:
      IllegalArgumentException - if the given SocketAddress is invalid or not supported or the timeout value is negative.
      IOException - if the socket is already connected or an error occurs while connecting.

    • isInputShutdown

      public boolean isInputShutdown()
      Returns whether the incoming channel of the socket has already been closed.
      Returns:
      true if reading from this socket is not possible anymore, false otherwise.

    • isOutputShutdown

      public boolean isOutputShutdown()
      Returns whether the outgoing channel of the socket has already been closed.
      Returns:
      true if writing to this socket is not possible anymore, false otherwise.

    • setReuseAddress

      public void setReuseAddress​(boolean reuse) throws SocketException
      Sets this socket's SocketOptions.SO_REUSEADDR option.
      Throws:
      SocketException

    • getReuseAddress

      public boolean getReuseAddress() throws SocketException
      Returns this socket's SocketOptions.SO_REUSEADDR setting.
      Throws:
      SocketException

    • setOOBInline

      public void setOOBInline​(boolean oobinline) throws SocketException
      Sets this socket's SocketOptions.SO_OOBINLINE option.
      Throws:
      SocketException

    • getOOBInline

      public boolean getOOBInline() throws SocketException
      Returns this socket's SocketOptions.SO_OOBINLINE setting.
      Throws:
      SocketException

    • setTrafficClass

      public void setTrafficClass​(int value) throws SocketException
      Sets this socket's SocketOptions.IP_TOS value for every packet sent by this socket.
      Throws:
      SocketException

    • getTrafficClass

      public int getTrafficClass() throws SocketException
      Returns this socket's {@see SocketOptions#IP_TOS} setting.
      Throws:
      SocketException

    • sendUrgentData

      public void sendUrgentData​(int value) throws IOException
      Sends the given single byte data which is represented by the lowest octet of value as "TCP urgent data".
      Parameters:
      value - the byte of urgent data to be sent.
      Throws:
      IOException - if an error occurs while sending urgent data.

    • getChannel

      public SocketChannel getChannel()
      Returns this socket's SocketChannel, if one exists. A channel is available only if this socket wraps a channel. (That is, you can go from a channel to a socket and back again, but you can't go from an arbitrary socket to a channel.) In practice, this means that the socket must have been created by ServerSocketChannel.accept() or SocketChannel.open().

    • getFileDescriptor$

      public FileDescriptor getFileDescriptor$()

    • setPerformancePreferences

      public void setPerformancePreferences​(int connectionTime, int latency, int bandwidth)
      Sets performance preferences for connectionTime, latency and bandwidth.

      This method does currently nothing.

      Parameters:
      connectionTime - the value representing the importance of a short connecting time.
      latency - the value representing the importance of low latency.
      bandwidth - the value representing the importance of high bandwidth.