org.springframework.util

Class SocketUtils

java.lang.Object

org.springframework.util.SocketUtils

public class SocketUtils
extends java.lang.Object

Simple utility methods for working with network sockets — for example, for finding available ports on localhost.

Within this class, a TCP port refers to a port for a ServerSocket; whereas, a UDP port refers to a port for a DatagramSocket.

Since:

4.0

Author:

Sam Brannen, Ben Hale, Arjen Poutsma, Gunnar Hillert, Gary Russell

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	SocketUtils.SocketType

Field Summary

Fields

Modifier and Type	Field and Description
static int	PORT_RANGE_MAX The default maximum value for port ranges used when finding an available socket port.
static int	PORT_RANGE_MIN The default minimum value for port ranges used when finding an available socket port.
private static java.util.Random	random

Constructor Summary

Constructors

Constructor and Description
SocketUtils() Although SocketUtils consists solely of static utility methods, this constructor is intentionally public.

Method Summary

Modifier and Type	Method and Description
static int	findAvailableTcpPort() Find an available TCP port randomly selected from the range [1024, 65535].
static int	findAvailableTcpPort(int minPort) Find an available TCP port randomly selected from the range [minPort, 65535].
static int	findAvailableTcpPort(int minPort, int maxPort) Find an available TCP port randomly selected from the range [minPort, maxPort].
static java.util.SortedSet<java.lang.Integer>	findAvailableTcpPorts(int numRequested) Find the requested number of available TCP ports, each randomly selected from the range [1024, 65535].
static java.util.SortedSet<java.lang.Integer>	findAvailableTcpPorts(int numRequested, int minPort, int maxPort) Find the requested number of available TCP ports, each randomly selected from the range [minPort, maxPort].
static int	findAvailableUdpPort() Find an available UDP port randomly selected from the range [1024, 65535].
static int	findAvailableUdpPort(int minPort) Find an available UDP port randomly selected from the range [minPort, 65535].
static int	findAvailableUdpPort(int minPort, int maxPort) Find an available UDP port randomly selected from the range [minPort, maxPort].
static java.util.SortedSet<java.lang.Integer>	findAvailableUdpPorts(int numRequested) Find the requested number of available UDP ports, each randomly selected from the range [1024, 65535].
static java.util.SortedSet<java.lang.Integer>	findAvailableUdpPorts(int numRequested, int minPort, int maxPort) Find the requested number of available UDP ports, each randomly selected from the range [minPort, maxPort].

Methods inherited from class java.lang.Object

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

Field Detail

PORT_RANGE_MIN

public static final int PORT_RANGE_MIN

The default minimum value for port ranges used when finding an available socket port.

See Also:

Constant Field Values

PORT_RANGE_MAX

public static final int PORT_RANGE_MAX

The default maximum value for port ranges used when finding an available socket port.

See Also:

Constant Field Values

random

private static final java.util.Random random

Constructor Detail

SocketUtils

public SocketUtils()

Although SocketUtils consists solely of static utility methods, this constructor is intentionally public.

Rationale

Static methods from this class may be invoked from within XML configuration files using the Spring Expression Language (SpEL) and the following syntax.

<bean id="bean1" ... p:port="#{T(org.springframework.util.SocketUtils).findAvailableTcpPort(12000)}" />

If this constructor were private, you would be required to supply the fully qualified class name to SpEL's T() function for each usage. Thus, the fact that this constructor is public allows you to reduce boilerplate configuration with SpEL as can be seen in the following example.

<bean id="socketUtils" class="org.springframework.util.SocketUtils" />
 <bean id="bean1" ... p:port="#{socketUtils.findAvailableTcpPort(12000)}" />
 <bean id="bean2" ... p:port="#{socketUtils.findAvailableTcpPort(30000)}" />

Method Detail

findAvailableTcpPort

public static int findAvailableTcpPort()

Find an available TCP port randomly selected from the range [1024, 65535].

Returns:

an available TCP port number

Throws:

java.lang.IllegalStateException - if no available port could be found

findAvailableTcpPort

public static int findAvailableTcpPort(int minPort)

Find an available TCP port randomly selected from the range [minPort, 65535].

Parameters:

minPort - the minimum port number

Returns:

an available TCP port number

Throws:

java.lang.IllegalStateException - if no available port could be found

findAvailableTcpPort

public static int findAvailableTcpPort(int minPort,
                                       int maxPort)

Find an available TCP port randomly selected from the range [minPort, maxPort].

Parameters:

minPort - the minimum port number

maxPort - the maximum port number

Returns:

an available TCP port number

Throws:

java.lang.IllegalStateException - if no available port could be found

findAvailableTcpPorts

public static java.util.SortedSet<java.lang.Integer> findAvailableTcpPorts(int numRequested)

Find the requested number of available TCP ports, each randomly selected from the range [1024, 65535].

Parameters:

numRequested - the number of available ports to find

Returns:

a sorted set of available TCP port numbers

Throws:

java.lang.IllegalStateException - if the requested number of available ports could not be found

findAvailableTcpPorts

public static java.util.SortedSet<java.lang.Integer> findAvailableTcpPorts(int numRequested,
                                                                           int minPort,
                                                                           int maxPort)

Find the requested number of available TCP ports, each randomly selected from the range [minPort, maxPort].

Parameters:

numRequested - the number of available ports to find

minPort - the minimum port number

maxPort - the maximum port number

Returns:

a sorted set of available TCP port numbers

Throws:

java.lang.IllegalStateException - if the requested number of available ports could not be found

findAvailableUdpPort

public static int findAvailableUdpPort()

Find an available UDP port randomly selected from the range [1024, 65535].

Returns:

an available UDP port number

Throws:

java.lang.IllegalStateException - if no available port could be found

findAvailableUdpPort

public static int findAvailableUdpPort(int minPort)

Find an available UDP port randomly selected from the range [minPort, 65535].

Parameters:

minPort - the minimum port number

Returns:

an available UDP port number

Throws:

java.lang.IllegalStateException - if no available port could be found

findAvailableUdpPort

public static int findAvailableUdpPort(int minPort,
                                       int maxPort)

Find an available UDP port randomly selected from the range [minPort, maxPort].

Parameters:

minPort - the minimum port number

maxPort - the maximum port number

Returns:

an available UDP port number

Throws:

java.lang.IllegalStateException - if no available port could be found

findAvailableUdpPorts

public static java.util.SortedSet<java.lang.Integer> findAvailableUdpPorts(int numRequested)

Find the requested number of available UDP ports, each randomly selected from the range [1024, 65535].

Parameters:

numRequested - the number of available ports to find

Returns:

a sorted set of available UDP port numbers

Throws:

java.lang.IllegalStateException - if the requested number of available ports could not be found

findAvailableUdpPorts

public static java.util.SortedSet<java.lang.Integer> findAvailableUdpPorts(int numRequested,
                                                                           int minPort,
                                                                           int maxPort)

Find the requested number of available UDP ports, each randomly selected from the range [minPort, maxPort].

Parameters:

numRequested - the number of available ports to find

minPort - the minimum port number

maxPort - the maximum port number

Returns:

a sorted set of available UDP port numbers

Throws:

java.lang.IllegalStateException - if the requested number of available ports could not be found