Service-provider class for InetAddress resolvers.

A resolver provider is a factory for custom implementations of InetAddress resolvers. A resolver defines operations for looking up (resolving) host names and IP addresses.

A resolver provider is a concrete subclass of this class that has a zero-argument constructor and implements the abstract methods specified below.

A given invocation of the Java virtual machine maintains a single system-wide resolver instance, which is used by InetAddress. It is set after the VM is fully initialized and when an invocation of a method in InetAddress class triggers the first lookup operation.

A resolver provider is located and loaded by InetAddress to create the system-wide resolver as follows:

The ServiceLoader mechanism is used to locate an InetAddressResolverProvider using the system class loader. The order in which providers are located is implementation specific. The first provider found will be used to instantiate the InetAddressResolver by invoking the InetAddressResolverProvider#get(InetAddressResolverProvider.Configuration) method. The returned InetAddressResolver will be set as the system-wide resolver.
If the previous step fails to find any resolver provider the built-in resolver will be set as the system-wide resolver.

If instantiating a custom resolver from a provider discovered in step 1 throws an error or exception, the system-wide resolver will not be set and the error or exception will be propagated to the caller of the method that triggered the lookup operation. Otherwise, any lookup operation will be performed using the system-wide resolver.

Nested and Inner Type Summary

Modifier and Type	Class and Description
public static interface	InetAddressResolverProvider.Configuration A `Configuration` object is supplied to the `InetAddressResolverProvider#get(Configuration)` method when setting the system-wide resolver.

Field Summary

Modifier and Type	Field and Description
private static final RuntimePermission	INET_ADDRESS_RESOLVER_PERMISSION The `RuntimePermission("inetAddressResolverProvider")` is necessary to subclass and instantiate the `InetAddressResolverProvider` class, as well as to obtain resolver from an instance of that class, and it is also required to obtain the operating system name resolution configurations.

Access	Constructor and Description
protected	InetAddressResolverProvider() Creates a new instance of `InetAddressResolverProvider`.
private	InetAddressResolverProvider(Void unused)

Method Summary

Modifier and Type	Method and Description
private static Void	checkPermission()
public abstract InetAddressResolver	Returns: the resolver provided by this provider get(InetAddressResolverProvider.Configuration a `Configuration` instance containing platform built-in address resolution configuration. configuration) Initialize and return an `InetAddressResolver` provided by this provider.
public abstract String	Returns: the name of this provider, or `null` if unnamed name() Returns the name of this provider, or `null` if unnamed.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

INET_ADDRESS_RESOLVER_PERMISSION	back to summary
private static final RuntimePermission INET_ADDRESS_RESOLVER_PERMISSION The `RuntimePermission("inetAddressResolverProvider")` is necessary to subclass and instantiate the `InetAddressResolverProvider` class, as well as to obtain resolver from an instance of that class, and it is also required to obtain the operating system name resolution configurations.

Constructor Detail

InetAddressResolverProvider back to summary

InetAddressResolverProvider	back to summary
protected InetAddressResolverProvider() Creates a new instance of `InetAddressResolverProvider`. Implementation Note It is recommended that an `InetAddressResolverProvider` service implementation initialization should be as simple as possible, in order to avoid possible risks of deadlock or class loading cycles during the instantiation of the service provider. Exceptions SecurityException: if a security manager is present and its `checkPermission` method doesn't allow the `RuntimePermission("inetAddressResolverProvider")`.

protected InetAddressResolverProvider()

Creates a new instance of InetAddressResolverProvider.

Implementation Note

It is recommended that an InetAddressResolverProvider service implementation initialization should be as simple as possible, in order to avoid possible risks of deadlock or class loading cycles during the instantiation of the service provider.

Exceptions

SecurityException:: if a security manager is present and its checkPermission method doesn't allow the RuntimePermission("inetAddressResolverProvider").

InetAddressResolverProvider	back to summary
private InetAddressResolverProvider(Void unused)

Method Detail

checkPermission	back to summary
private static Void checkPermission() Annotations @SuppressWarnings:removal

get back to summary

get	back to summary
public abstract InetAddressResolver get(InetAddressResolverProvider.Configuration configuration) Initialize and return an `InetAddressResolver` provided by this provider. This method is called by `InetAddress` when installing the system-wide resolver implementation. Any error or exception thrown by this method is considered as a failure of `InetAddressResolver` instantiation and will be propagated to the caller of the method that triggered the lookup operation. Parameters configuration:InetAddressResolverProvider.Configuration a `Configuration` instance containing platform built-in address resolution configuration. Returns:InetAddressResolver the resolver provided by this provider

public abstract InetAddressResolver get(InetAddressResolverProvider.Configuration configuration)

Initialize and return an InetAddressResolver provided by this provider. This method is called by InetAddress when installing the system-wide resolver implementation.

Any error or exception thrown by this method is considered as a failure of InetAddressResolver instantiation and will be propagated to the caller of the method that triggered the lookup operation.

Parameters

configuration:InetAddressResolverProvider.Configuration: a Configuration instance containing platform built-in address resolution configuration.

Returns:InetAddressResolver

the resolver provided by this provider

name back to summary

name	back to summary
public abstract String name() Returns the name of this provider, or `null` if unnamed. Returns:String the name of this provider, or `null` if unnamed

public abstract String name()

Returns the name of this provider, or null if unnamed.

Returns:String: the name of this provider, or null if unnamed

java.net.spi back to summary

public sealed Interface InetAddressResolverProvider.Configuration

Known Direct Implementers: sun.net.ResolverProviderConfiguration

A Configuration object is supplied to the InetAddressResolverProvider#get(Configuration) method when setting the system-wide resolver. A resolver implementation can then delegate to the built-in resolver provided by this interface if it needs to.

Since: 18

Method Summary

Modifier and Type	Method and Description
public InetAddressResolver	Returns: the JDK built-in resolver. builtinResolver() Returns the built-in resolver.
public String	Returns: the localhost name. lookupLocalHostName() Reads the localhost name from the system configuration.

Method Detail

builtinResolver	back to summary
public InetAddressResolver builtinResolver() Returns the built-in resolver. Returns:InetAddressResolver the JDK built-in resolver.

builtinResolver

back to summary

public InetAddressResolver builtinResolver()

Returns the built-in resolver.

Returns:InetAddressResolver: the JDK built-in resolver.

lookupLocalHostName	back to summary
public String lookupLocalHostName() Reads the localhost name from the system configuration. Returns:String the localhost name.

lookupLocalHostName

back to summary

public String lookupLocalHostName()

Reads the localhost name from the system configuration.

Returns:String: the localhost name.

public abstract Class InetAddressResolverProvider

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

public sealed Interface InetAddressResolverProvider.Configuration

Method Summary

Method Detail