Module java.base
Package java.net.spi

Interface InetAddressResolver

public interface InetAddressResolver
This interface defines operations for looking up host names and IP addresses. InetAddress delegates all lookup operations to the system-wide resolver.

The system-wide resolver can be customized by deploying an implementation of InetAddressResolverProvider.

Since:
18

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static final class 
    InetAddressResolver.LookupPolicy
    A LookupPolicy object describes characteristics that can be applied to a lookup operation.

  • Method Summary

    Modifier and Type
    Method
    Description
    String
    lookupByAddress(byte[] addr)
    Lookup the host name corresponding to the raw IP address provided.
    Stream<InetAddress>
    lookupByName(String host, InetAddressResolver.LookupPolicy lookupPolicy)
    Given the name of a host, returns a stream of IP addresses of the requested address family associated with a provided hostname.

  • Method Details

    • lookupByName

      Stream<InetAddress> lookupByName(String host, InetAddressResolver.LookupPolicy lookupPolicy) throws UnknownHostException
      Given the name of a host, returns a stream of IP addresses of the requested address family associated with a provided hostname.

      host should be a machine name, such as "www.example.com", not a textual representation of its IP address. No validation is performed on the given host name: if a textual representation is supplied, the name resolution is likely to fail and UnknownHostException may be thrown.

      The address family type and addresses order are specified by the LookupPolicy instance. Lookup operation characteristics could be acquired with InetAddressResolver.LookupPolicy.characteristics(). If InetAddressResolver.LookupPolicy.IPV4 and InetAddressResolver.LookupPolicy.IPV6 characteristics provided then this method returns addresses of both IPV4 and IPV6 families.

      Parameters:
      host - the specified hostname
      lookupPolicy - the address lookup policy
      Returns:
      a stream of IP addresses for the requested host
      Throws:
      NullPointerException - if either parameter is null
      UnknownHostException - if no IP address for the host could be found
      See Also:

    • lookupByAddress

      String lookupByAddress(byte[] addr) throws UnknownHostException
      Lookup the host name corresponding to the raw IP address provided.

      addr argument is in network byte order: the highest order byte of the address is in addr[0].

      IPv4 address byte array must be 4 bytes long and IPv6 byte array must be 16 bytes long.

      Parameters:
      addr - byte array representing a raw IP address
      Returns:
      String representing the host name mapping
      Throws:
      UnknownHostException - if no host name is found for the specified IP address
      IllegalArgumentException - if the length of the provided byte array doesn't correspond to a valid IP address length
      NullPointerException - if addr is null