me.alexpanov.net

Class FreePortFinder

java.lang.Object

me.alexpanov.net.FreePortFinder

public final class FreePortFinder
extends Object

Finds currently available server ports.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_PORT_NUMBER The maximum server currentMinPort number for IPv4.
static int	MIN_PORT_NUMBER The minimum server currentMinPort number for IPv4.

Method Summary

Modifier and Type	Method and Description
static boolean	available(int port) Checks to see if a specific port is available.
static boolean	available(int port, InetAddress bindAddress) Checks to see if a specific port is available.
static int	findFreeLocalPort() Gets the next available port starting at the lowest number.
static int	findFreeLocalPort(InetAddress bindAddress) Gets the next available port starting at the lowest number.
static int	findFreeLocalPort(int fromPort) Gets the next available port starting at the lowest number.
static int	findFreeLocalPort(int fromPort, InetAddress bindAddress) Gets the next available port starting at a given from port.
static int	findFreeLocalPortOnAddresses(InetAddress... bindAddresses) Gets the next available port starting at a given from port.

Methods inherited from class java.lang.Object

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

Field Detail

MIN_PORT_NUMBER

public static final int MIN_PORT_NUMBER

The minimum server currentMinPort number for IPv4. Set at 1100 to avoid returning privileged currentMinPort numbers.

See Also:

Constant Field Values

MAX_PORT_NUMBER

public static final int MAX_PORT_NUMBER

The maximum server currentMinPort number for IPv4.

See Also:

Constant Field Values

Method Detail

findFreeLocalPort

public static int findFreeLocalPort()

Gets the next available port starting at the lowest number. This is the preferred method to use. The port return is immediately marked in use and doesn't rely on the caller actually opening the port.

Returns:

the available port

Throws:

IllegalArgumentException - is thrown if the port number is out of range

NoSuchElementException - if there are no ports available

findFreeLocalPort

public static int findFreeLocalPort(InetAddress bindAddress)

Gets the next available port starting at the lowest number. This is the preferred method to use. The port return is immediately marked in use and doesn't rely on the caller actually opening the port.

Parameters:

bindAddress - the address that will try to bind

Returns:

the available port

Throws:

IllegalArgumentException - is thrown if the port number is out of range

NoSuchElementException - if there are no ports available

findFreeLocalPort

public static int findFreeLocalPort(int fromPort)

Gets the next available port starting at the lowest number. This is the preferred method to use. The port return is immediately marked in use and doesn't rely on the caller actually opening the port.

Returns:

the available port

Throws:

IllegalArgumentException - is thrown if the port number is out of range

NoSuchElementException - if there are no ports available

findFreeLocalPort

public static int findFreeLocalPort(int fromPort,
                                    InetAddress bindAddress)

Gets the next available port starting at a given from port.

Parameters:

fromPort - the from port to scan for availability

bindAddress - the address that will try to bind

Returns:

the available port

Throws:

IllegalArgumentException - is thrown if the port number is out of range

NoSuchElementException - if there are no ports available

findFreeLocalPortOnAddresses

public static int findFreeLocalPortOnAddresses(InetAddress... bindAddresses)

Gets the next available port starting at a given from port.

Parameters:

bindAddresses - the addresses that will try to bind

Returns:

the available port

Throws:

IllegalArgumentException - is thrown if the port number is out of range

NoSuchElementException - if there are no ports available

available

public static boolean available(int port)
                         throws IllegalArgumentException

Checks to see if a specific port is available.

Parameters:

port - the port number to check for availability

Returns:

true if the port is available, or false if not

Throws:

IllegalArgumentException - is thrown if the port number is out of range

available

public static boolean available(int port,
                                InetAddress bindAddress)
                         throws IllegalArgumentException

Checks to see if a specific port is available.

Parameters:

port - the port number to check for availability

bindAddress - the address that will try to bind

Returns:

true if the port is available, or false if not

Throws:

IllegalArgumentException - is thrown if the port number is out of range