1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 *
21 * This software consists of voluntary contributions made by many
22 * individuals on behalf of the Apache Software Foundation. For more
23 * information on the Apache Software Foundation, please see
24 * <http://www.apache.org/>.
25 *
26 */
27 package org.apache.hc.client5.http.impl.cache;
28
29 import java.net.InetAddress;
30 import java.net.UnknownHostException;
31 import java.security.NoSuchAlgorithmException;
32 import java.security.SecureRandom;
33 import java.util.Formatter;
34 import java.util.Locale;
35
36 /**
37 * Should produce reasonably unique tokens.
38 */
39 class BasicIdGenerator {
40
41 private final String hostname;
42 private final SecureRandom rnd;
43
44 private long count;
45
46 public BasicIdGenerator() {
47 super();
48 String hostname;
49 try {
50 hostname = InetAddress.getLocalHost().getHostName();
51 } catch (final UnknownHostException ex) {
52 hostname = "localhost";
53 }
54 this.hostname = hostname;
55 try {
56 this.rnd = SecureRandom.getInstance("SHA1PRNG");
57 } catch (final NoSuchAlgorithmException ex) {
58 throw new Error(ex);
59 }
60 this.rnd.setSeed(System.currentTimeMillis());
61 }
62
63 public synchronized void generate(final StringBuilder buffer) {
64 this.count++;
65 final int rndnum = this.rnd.nextInt();
66 buffer.append(System.currentTimeMillis());
67 buffer.append('.');
68 try (Formatter formatter = new Formatter(buffer, Locale.ROOT)) {
69 formatter.format("%1$016x-%2$08x", this.count, rndnum);
70 }
71 buffer.append('.');
72 buffer.append(this.hostname);
73 }
74
75 public String generate() {
76 final StringBuilder buffer = new StringBuilder();
77 generate(buffer);
78 return buffer.toString();
79 }
80
81 }