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1
33
34 package com.icesoft.util;
35
36 import com.icesoft.util.encoding.Base64;
37
38 import java.net.InetAddress  ;
39 import java.net.UnknownHostException ;
40 import java.security.MessageDigest ;
41 import java.security.NoSuchAlgorithmException ;
42 import java.util.Random ;
43
44 import org.apache.commons.logging.Log;
45 import org.apache.commons.logging.LogFactory;
46
47
52 public class IdGenerator {
53 private String seed;
54 private long counter;
55 private String ipAddress;
56 private static MessageDigest md5;
57
58
59 public IdGenerator() {
60 this(String.valueOf(new Random ().nextInt()));
61 }
62
63 public IdGenerator(String seed) {
64 this.seed = seed.trim();
65 this.counter = 0;
66 try {
67 ipAddress = InetAddress.getLocalHost().getHostAddress();
68 md5 = MessageDigest.getInstance("MD5");
69 } catch (NoSuchAlgorithmException e) {
70 throw new RuntimeException (e);
71 } catch (UnknownHostException e) {
72 throw new RuntimeException (e);
73 }
74 }
75
76
80 public synchronized String newIdentifier() {
81 StringBuffer buffer = new StringBuffer ();
82 buffer.append(++counter);
83 buffer.append(System.currentTimeMillis());
84 buffer.append(seed);
85 buffer.append(ipAddress);
86 buffer.append(Math.random());
87 byte[] digest = md5.digest(buffer.toString().getBytes());
88 byte[] encodedDigest = Base64.encodeForURL(digest);
89 return new String (encodedDigest);
90 }
91 }
92 |
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