001/*
002 * Copyright 2002-2015 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.util;
018
019import java.util.UUID;
020import java.util.concurrent.atomic.AtomicLong;
021
022/**
023 * A simple {@link IdGenerator} that starts at 1 and increments by 1 with each call.
024 *
025 * @author Rossen Stoyanchev
026 * @since 4.1.5
027 */
028public class SimpleIdGenerator implements IdGenerator {
029
030        private final AtomicLong mostSigBits = new AtomicLong(0);
031
032        private final AtomicLong leastSigBits = new AtomicLong(0);
033
034
035        @Override
036        public UUID generateId() {
037                long leastSigBits = this.leastSigBits.incrementAndGet();
038                if (leastSigBits == 0) {
039                        this.mostSigBits.incrementAndGet();
040                }
041                return new UUID(this.mostSigBits.get(), leastSigBits);
042        }
043
044}