001/*
002 * Copyright 2012-2017 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 *      http://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.boot.system;
018
019import java.util.Arrays;
020import java.util.Collections;
021import java.util.List;
022
023import org.springframework.util.ClassUtils;
024
025/**
026 * Supported Java versions.
027 *
028 * @author Oliver Gierke
029 * @author Phillip Webb
030 * @since 2.0.0
031 */
032public enum JavaVersion {
033
034        /**
035         * Java 1.8.
036         */
037        EIGHT("1.8", "java.util.function.Function"),
038
039        /**
040         * Java 1.9.
041         */
042        NINE("1.9", "java.security.cert.URICertStoreParameters");
043
044        private final String name;
045
046        private final boolean available;
047
048        JavaVersion(String name, String className) {
049                this.name = name;
050                this.available = ClassUtils.isPresent(className, getClass().getClassLoader());
051        }
052
053        @Override
054        public String toString() {
055                return this.name;
056        }
057
058        /**
059         * Returns the {@link JavaVersion} of the current runtime.
060         * @return the {@link JavaVersion}
061         */
062        public static JavaVersion getJavaVersion() {
063                List<JavaVersion> candidates = Arrays.asList(JavaVersion.values());
064                Collections.reverse(candidates);
065                for (JavaVersion candidate : candidates) {
066                        if (candidate.available) {
067                                return candidate;
068                        }
069                }
070                return EIGHT;
071        }
072
073        /**
074         * Return if this version is equal to or newer than a given version.
075         * @param version the version to compare
076         * @return {@code true} if this version is equal to or newer than {@code version}
077         */
078        public boolean isEqualOrNewerThan(JavaVersion version) {
079                return compareTo(version) >= 0;
080        }
081
082        /**
083         * Return if this version is older than a given version.
084         * @param version the version to compare
085         * @return {@code true} if this version is older than {@code version}
086         */
087        public boolean isOlderThan(JavaVersion version) {
088                return compareTo(version) < 0;
089        }
090
091}