# Class SocketFactory

java.lang.Object
javax.net.SocketFactory

Direct Known Subclasses:
  `SSLSocketFactory`

public abstract class SocketFactory extends Object
This class creates sockets. It may be subclassed by other factories, which create particular subclasses of sockets and thus provide a general framework for the addition of public socket-level functionality.

Socket factories are a simple way to capture a variety of policies related to the sockets being constructed, producing such sockets in a way which does not require special configuration of the code which asks for the sockets:

- Due to polymorphism of both factories and sockets, different kinds of sockets can be used by the same application code just by passing it different kinds of factories.
- Factories can themselves be customized with parameters used in socket construction. So for example, factories could be customized to return sockets with different networking timeouts or security parameters already configured.
- The sockets returned to the application can be subclasses of java.net.Socket, so that they can directly expose new APIs for features such as compression, security, record marking, statistics collection, or firewall tunneling.

Factory classes are specified by environment-specific configuration mechanisms. For example, the getDefault method could return a factory that was appropriate for a particular application, and a framework could use a factory customized to its own purposes.

Since:
  1.4
See Also:
  - `ServerSocketFactory`

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `SocketFactory()`
  Creates a `SocketFactory`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `Socket`
  `createSocket()`
  Creates an unconnected socket.
  `abstract Socket`
  `createSocket(String host, int port)`
  Creates a socket and connects it to the specified remote host at the specified remote port.
  `abstract Socket`
  `createSocket(String host, int port, InetAddress localHost, int localPort)`
  Creates a socket and connects it to the specified remote host on the specified remote port.
  `abstract Socket`
  `createSocket(InetAddress host, int port)`
  Creates a socket and connects it to the specified port number at the specified address.
  `abstract Socket`
  `createSocket(InetAddress address, int port, InetAddress localAddress, int localPort)`
  Creates a socket and connect it to the specified remote address on the specified remote port.
  `static SocketFactory`
  `getDefault()`
  Returns a copy of the environment's default socket factory.

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### SocketFactory

    protected SocketFactory()
    Creates a `SocketFactory`.

- ## Method Details

  - ### getDefault

    public static SocketFactory getDefault()
    Returns a copy of the environment's default socket factory.
    Returns:
      the default `SocketFactory`

  - ### createSocket

    public Socket createSocket() throws IOException
    Creates an unconnected socket.
    Returns:
      the unconnected socket
    Throws:
      `IOException` - if the socket cannot be created
    See Also:
      - `Socket.connect(java.net.SocketAddress)`
      - `Socket.connect(java.net.SocketAddress, int)`
      - `Socket()`

  - ### createSocket

    public abstract Socket createSocket(String host, int port) throws IOException, UnknownHostException
    Creates a socket and connects it to the specified remote host at the specified remote port. This socket is configured using the socket options established for this factory.
    Parameters:
      `host` - the server host name with which to connect, or `null` for the loopback address.
      `port` - the server port
    Returns:
      the `Socket`
    Throws:
      `IOException` - if an I/O error occurs when creating the socket
      `UnknownHostException` - if the host is not known
      `IllegalArgumentException` - if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.
    See Also:
      - `Socket(String, int)`

  - ### createSocket

    public abstract Socket createSocket(String host, int port, InetAddress localHost, int localPort) throws IOException, UnknownHostException
    Creates a socket and connects it to the specified remote host on the specified remote port. The socket will also be bound to the local address and port supplied. This socket is configured using the socket options established for this factory.
    Parameters:
      `host` - the server host name with which to connect, or `null` for the loopback address.
      `port` - the server port
      `localHost` - the local address the socket is bound to
      `localPort` - the local port the socket is bound to
    Returns:
      the `Socket`
    Throws:
      `IOException` - if an I/O error occurs when creating the socket
      `UnknownHostException` - if the host is not known
      `IllegalArgumentException` - if the port parameter or localPort parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.
    See Also:
      - `Socket(String, int, java.net.InetAddress, int)`

  - ### createSocket

    public abstract Socket createSocket(InetAddress host, int port) throws IOException
    Creates a socket and connects it to the specified port number at the specified address. This socket is configured using the socket options established for this factory.
    Parameters:
      `host` - the server host
      `port` - the server port
    Returns:
      the `Socket`
    Throws:
      `IOException` - if an I/O error occurs when creating the socket
      `IllegalArgumentException` - if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.
      `NullPointerException` - if `host` is null.
    See Also:
      - `Socket(java.net.InetAddress, int)`

  - ### createSocket

    public abstract Socket createSocket(InetAddress address, int port, InetAddress localAddress, int localPort) throws IOException
    Creates a socket and connect it to the specified remote address on the specified remote port. The socket will also be bound to the local address and port supplied. The socket is configured using the socket options established for this factory.
    Parameters:
      `address` - the server network address
      `port` - the server port
      `localAddress` - the client network address
      `localPort` - the client port
    Returns:
      the `Socket`
    Throws:
      `IOException` - if an I/O error occurs when creating the socket
      `IllegalArgumentException` - if the port parameter or localPort parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.
      `NullPointerException` - if `address` is null.
    See Also:
      - `Socket(java.net.InetAddress, int, java.net.InetAddress, int)`