/** * Copyright (c) 2011-2017, 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.kit; import java.security.SecureRandom; import java.util.Random; import javax.servlet.http.HttpServletRequest; /** * SessionIdKit. */ public class SessionIdKit { protected static Random random; private static boolean weakRandom; /** * Lazy initialization holder class pattern */ private static class FieldHolder { static final SessionIdKit sessionIdKit = new SessionIdKit(); } private SessionIdKit() { 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 SessionIdKit me() { return FieldHolder.sessionIdKit; } public String generate(HttpServletRequest request) { 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; } }