/**
* Copyright (c) 2011-2012, James Zhan 詹波 (jfinal@126.com).
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.jfinal.ext.util;
import java.security.SecureRandom;
import java.util.Random;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* SessionIdGenerator.
*/
public class SessionIdGenerator {
protected static Random random;
private static boolean weakRandom;
private static volatile Object lock = new Object();
private static final SessionIdGenerator me = new SessionIdGenerator();
private SessionIdGenerator() {
try {
// This operation may block on some systems with low entropy. See
// this page
// for workaround suggestions:
// http://docs.codehaus.org/display/JETTY/Connectors+slow+to+startup
System.out.println("Init SecureRandom.");
random = new SecureRandom();
weakRandom = false;
} catch (Exception e) {
System.err.println("Could not generate SecureRandom for session-id randomness");
random = new Random();
weakRandom = true;
}
}
public static final SessionIdGenerator me() {
return me;
}
public String generate(HttpServletRequest request, HttpServletResponse response) {
synchronized (lock) {
String id = null;
while (id == null || id.length() == 0) { //)||idInUse(id))
long r0 = weakRandom ? (hashCode()^Runtime.getRuntime().freeMemory()^random.nextInt()^(((long)request.hashCode())<<32)) : random.nextLong();
long r1 = random.nextLong();
if (r0<0) r0 = -r0;
if (r1<0) r1 = -r1;
id=Long.toString(r0,36)+Long.toString(r1,36);
}
return id;
}
}
}