Move JavaVersion to a reusable location.

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/ConditionalOnJava.java

@@ -22,9 +22,8 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.springframework.boot.system.JavaVersion;
 import org.springframework.context.annotation.Conditional;
-import org.springframework.util.Assert;
-import org.springframework.util.ClassUtils;
 
 /**
  * {@link Conditional} that matches based on the JVM version the application is running
@@ -73,69 +72,4 @@ public @interface ConditionalOnJava {
 
 	}
 
-	/**
-	 * Java versions.
-	 */
-	enum JavaVersion {
-
-		/**
-		 * Java 1.9.
-		 */
-		NINE(9, "1.9", "java.security.cert.URICertStoreParameters"),
-
-		/**
-		 * Java 1.8.
-		 */
-		EIGHT(8, "1.8", "java.util.function.Function");
-
-		private final int value;
-
-		private final String name;
-
-		private final boolean available;
-
-		JavaVersion(int value, String name, String className) {
-			this.value = value;
-			this.name = name;
-			this.available = ClassUtils.isPresent(className, getClass().getClassLoader());
-		}
-
-		/**
-		 * Determines if this version is within the specified range of versions.
-		 * @param range the range
-		 * @param version the bounds of the range
-		 * @return if this version is within the specified range
-		 */
-		public boolean isWithin(Range range, JavaVersion version) {
-			Assert.notNull(range, "Range must not be null");
-			Assert.notNull(version, "Version must not be null");
-			switch (range) {
-			case EQUAL_OR_NEWER:
-				return this.value >= version.value;
-			case OLDER_THAN:
-				return this.value < version.value;
-			}
-			throw new IllegalStateException("Unknown range " + range);
-		}
-
-		@Override
-		public String toString() {
-			return this.name;
-		}
-
-		/**
-		 * Returns the {@link JavaVersion} of the current runtime.
-		 * @return the {@link JavaVersion}
-		 */
-		public static JavaVersion getJavaVersion() {
-			for (JavaVersion candidate : JavaVersion.values()) {
-				if (candidate.available) {
-					return candidate;
-				}
-			}
-			return EIGHT;
-		}
-
-	}
-
 }

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnJavaCondition.java

@@ -18,8 +18,8 @@ package org.springframework.boot.autoconfigure.condition;
 
 import java.util.Map;
 
-import org.springframework.boot.autoconfigure.condition.ConditionalOnJava.JavaVersion;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnJava.Range;
+import org.springframework.boot.system.JavaVersion;
 import org.springframework.context.annotation.Condition;
 import org.springframework.context.annotation.ConditionContext;
 import org.springframework.core.Ordered;
@@ -51,7 +51,7 @@ class OnJavaCondition extends SpringBootCondition {
 
 	protected ConditionOutcome getMatchOutcome(Range range, JavaVersion runningVersion,
 			JavaVersion version) {
-		boolean match = runningVersion.isWithin(range, version);
+		boolean match = isWithin(runningVersion, range, version);
 		String expected = String.format(
 				range == Range.EQUAL_OR_NEWER ? "(%s or newer)" : "(older than %s)",
 				version);
@@ -61,4 +61,22 @@ class OnJavaCondition extends SpringBootCondition {
 		return new ConditionOutcome(match, message);
 	}
 
+	/**
+	 * Determines if the {@code runningVersion} is within the specified range of versions.
+	 * @param runningVersion the current version.
+	 * @param range the range
+	 * @param version the bounds of the range
+	 * @return if this version is within the specified range
+	 */
+	private boolean isWithin(JavaVersion runningVersion, Range range, JavaVersion version) {
+		int i = runningVersion.compareTo(version);
+		if (range == Range.EQUAL_OR_NEWER) {
+			return i >= 0;
+		}
+		else if (range == Range.OLDER_THAN) {
+			return i < 0;
+		}
+		throw new IllegalStateException("Unknown range " + range);
+	}
+
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnJavaTests.java

@@ -27,8 +27,8 @@ import java.util.function.Function;
 
 import org.junit.Test;
 
-import org.springframework.boot.autoconfigure.condition.ConditionalOnJava.JavaVersion;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnJava.Range;
+import org.springframework.boot.system.JavaVersion;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -107,7 +107,7 @@ public class ConditionalOnJavaTests {
 		URL[] urls = ((URLClassLoader) getClass().getClassLoader()).getURLs();
 		URLClassLoader classLoader = new ClassHidingClassLoader(urls, hiddenClasses);
 		Class<?> javaVersionClass = classLoader
-				.loadClass(ConditionalOnJava.JavaVersion.class.getName());
+				.loadClass(JavaVersion.class.getName());
 		Method getJavaVersionMethod = ReflectionUtils.findMethod(javaVersionClass,
 				"getJavaVersion");
 		Object javaVersion = ReflectionUtils.invokeMethod(getJavaVersionMethod, null);

spring-boot/src/main/java/org/springframework/boot/system/JavaVersion.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2012-2017 the original author or authors.
+ *
+ * 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 org.springframework.boot.system;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.util.ClassUtils;
+
+/**
+ * Supported Java versions.
+ *
+ * @author Oliver Gierke
+ * @author Phillip Webb
+ * @since 2.0.0
+ */
+public enum JavaVersion {
+
+	/**
+	 * Java 1.8.
+	 */
+	EIGHT("1.8", "java.util.function.Function"),
+
+	/**
+	 * Java 1.9.
+	 */
+	NINE("1.9", "java.security.cert.URICertStoreParameters");
+
+	private final String name;
+
+	private final boolean available;
+
+	JavaVersion(String name, String className) {
+		this.name = name;
+		this.available = ClassUtils.isPresent(className, getClass().getClassLoader());
+	}
+
+	@Override
+	public String toString() {
+		return this.name;
+	}
+
+	/**
+	 * Returns the {@link JavaVersion} of the current runtime.
+	 * @return the {@link JavaVersion}
+	 */
+	public static JavaVersion getJavaVersion() {
+		List<JavaVersion> candidates = Arrays.asList(JavaVersion.values());
+		Collections.reverse(candidates);
+		for (JavaVersion candidate : candidates) {
+			if (candidate.available) {
+				return candidate;
+			}
+		}
+		return EIGHT;
+	}
+
+}

spring-boot/src/test/java/org/springframework/boot/system/JavaVersionTests.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2012-2017 the original author or authors.
+ *
+ * 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 org.springframework.boot.system;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link JavaVersion}.
+ *
+ * @author Stephane Nicoll
+ */
+public class JavaVersionTests {
+
+	@Test
+	public void currentVersionIsAvailable() {
+		assertThat(JavaVersion.getJavaVersion()).isNotNull();
+	}
+
+	@Test
+	public void java8IsOlderThanJava9() {
+		assertThat(JavaVersion.EIGHT.compareTo(JavaVersion.NINE)).isLessThan(0);
+	}
+
+	@Test
+	public void java9IsNewerThanJava8() {
+		assertThat(JavaVersion.NINE.compareTo(JavaVersion.EIGHT)).isGreaterThan(0);
+	}
+
+	@Test
+	public void comparisonOfSameVersion() {
+		assertThat(JavaVersion.EIGHT.compareTo(JavaVersion.EIGHT)).isEqualTo(0);
+	}
+
+}