File	Doc	Category	Size	Date	Package
VMID.java	API Doc	Java SE 5 API	4284	Fri Aug 26 14:57:12 BST 2005	java.rmi.dgc

VMID

• java.lang.Object

Fields Summary
private static byte[]	localAddr array of bytes uniquely identifying this host
private byte[]	addr
private UID	uid
private static final long	serialVersionUID indicate compatibility with JDK 1.1.x version of class

Constructors Summary
public VMID() Create a new VMID. Each new VMID returned from this constructor is unique for all Java virtual machines under the following conditions: a) the conditions for uniqueness for objects of the class java.rmi.server.UID are satisfied, and b) an address can be obtained for this host that is unique and constant for the lifetime of this object. addr = localAddr; uid = new UID();

Methods Summary
private static byte[]	computeAddressHash() Compute the hash an IP address. The hash is the first 8 bytes of the SHA digest of the IP address. /* * Get the local host's IP address. */ byte[] addr = (byte[]) java.security.AccessController.doPrivileged( new PrivilegedAction() { public Object run() { try { return InetAddress.getLocalHost().getAddress(); } catch (Exception e) { } return new byte[] { 0, 0, 0, 0 }; } }); byte[] addrHash; final int ADDR_HASH_LENGTH = 8; try { /* * Calculate message digest of IP address using SHA. */ MessageDigest md = MessageDigest.getInstance("SHA"); ByteArrayOutputStream sink = new ByteArrayOutputStream(64); DataOutputStream out = new DataOutputStream( new DigestOutputStream(sink, md)); out.write(addr, 0, addr.length); out.flush(); byte digest[] = md.digest(); int hashlength = Math.min(ADDR_HASH_LENGTH, digest.length); addrHash = new byte[hashlength]; System.arraycopy(digest, 0, addrHash, 0, hashlength); } catch (IOException ignore) { /* can't happen, but be deterministic anyway. */ addrHash = new byte[0]; } catch (NoSuchAlgorithmException complain) { throw new InternalError(complain.toString()); } return addrHash;
public boolean	equals(java.lang.Object obj) Compare this VMID to another, and return true if they are the same identifier. if (obj instanceof VMID) { VMID vmid = (VMID) obj; if (!uid.equals(vmid.uid)) return false; if ((addr == null) ^ (vmid.addr == null)) return false; if (addr != null) { if (addr.length != vmid.addr.length) return false; for (int i = 0; i < addr.length; ++ i) if (addr[i] != vmid.addr[i]) return false; } return true; } else { return false; }
public int	hashCode() Compute hash code for this VMID. return uid.hashCode();
public static boolean	isUnique() Return true if an accurate address can be determined for this host. If false, reliable VMID cannot be generated from this host return true if host address can be determined, false otherwise deprecated return true;
public java.lang.String	toString() Return string representation of this VMID. StringBuffer result = new StringBuffer(); if (addr != null) for (int i = 0; i < addr.length; ++ i) { int x = (int) (addr[i] & 0xFF); result.append((x < 0x10 ? "0" : "") + Integer.toString(x, 16)); } result.append(':"); result.append(uid.toString()); return result.toString();