Polish ConditionalOnJava

Apply formating and simplify the condition implementation. Delegate
to Spring's JdkVersion class to obtain the running version.

Author: Phillip Webb

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

@@ -22,13 +22,15 @@
 import java.lang.annotation.Target;
 
 import org.springframework.context.annotation.Conditional;
+import org.springframework.core.JdkVersion;
 import org.springframework.util.Assert;
 
 /**
  * {@link Conditional} that matches based on the JVM version the application is running
  * on.
- *
+ * 
  * @author Oliver Gierke
+ * @author Phillip Webb
  * @since 1.1.0
  */
 @Target({ ElementType.TYPE, ElementType.METHOD })
@@ -41,7 +43,6 @@
 	 * Configures whether the value configured in {@link #value()} shall be considered the
 	 * upper exclusive or lower inclusive boundary. Defaults to
 	 * {@link Range#EQUAL_OR_NEWER}.
-	 * @return the range of the version
 	 */
 	Range range() default Range.EQUAL_OR_NEWER;
 
@@ -51,66 +52,91 @@
 	 */
 	JavaVersion value();
 
+	/**
+	 * Range options.
+	 */
 	public enum Range {
 
-		OLDER_THAN("older than %s"), EQUAL_OR_NEWER("%s or newer");
-
-		private final String message;
+		/**
+		 * Equal to, or newer than the specified {@link JavaVersion}.
+		 */
+		EQUAL_OR_NEWER,
 
-		private Range(String message) {
-			this.message = message;
-		}
+		/**
+		 * Older than the specified {@link JavaVersion}.
+		 */
+		OLDER_THAN;
 
-		public String getMessage(JavaVersion version) {
-			return String.format(this.message, version);
-		}
 	}
 
 	/**
-	 * An enum to abstract major Java versions.
+	 * Java versions.
 	 */
 	public enum JavaVersion {
 
-		FIVE("1.5"), SIX("1.6"), SEVEN("1.7"), EIGHT("1.8"), NINE("1.9");
+		/**
+		 * Java 1.6.
+		 */
+		SIX(JdkVersion.JAVA_16, "1.6"),
 
-		private String value;
+		/**
+		 * Java 1.7.
+		 */
+		SEVEN(JdkVersion.JAVA_17, "1.7"),
 
-		private JavaVersion(String value) {
-			this.value = value;
-		}
+		/**
+		 * Java 1.8.
+		 */
+		EIGHT(JdkVersion.JAVA_18, "1.8"),
 
 		/**
-		 * Returns the {@link JavaVersion} of the current runtime.
+		 * Java 1.9.
 		 */
-		public static JavaVersion fromRuntime() {
+		NINE(JdkVersion.JAVA_19, "1.9");
 
-			String source = System.getProperty("java.version");
+		private final int value;
 
-			for (JavaVersion version : JavaVersion.values()) {
-				if (source.startsWith(version.value)) {
-					return version;
-				}
-			}
+		private final String name;
 
-			throw new IllegalArgumentException(String.format(
-					"Could not detect Java version for %s.", source));
+		private JavaVersion(int value, String name) {
+			this.value = value;
+			this.name = name;
 		}
 
 		/**
-		 * Returns whether the given {@link JavaVersion} is considered equal or better
-		 * than the given one.
-		 *
-		 * @param version must not be {code null}.
+		 * 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 isEqualOrBetter(JavaVersion version) {
-
-			Assert.notNull(version, "Java version must not be null!");
-			return this.value.compareTo(version.value) >= 0;
+		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.value;
+			return this.name;
+		}
+
+		/**
+		 * Returns the {@link JavaVersion} of the current runtime.
+		 */
+		public static JavaVersion getJavaVersion() {
+			int version = JdkVersion.getMajorJavaVersion();
+			for (JavaVersion candidate : JavaVersion.values()) {
+				if (candidate.value == version) {
+					return candidate;
+				}
+			}
+			return SIX;
 		}
 	}
 }

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

@@ -26,40 +26,35 @@
 
 /**
  * {@link Condition} that checks for a required version of Java
- *
+ * 
  * @author Oliver Gierke
+ * @author Phillip Webb
  * @see ConditionalOnJava
  * @since 1.1.0
  */
 class OnJavaCondition extends SpringBootCondition {
 
-	private static final JavaVersion JVM_VERSION = JavaVersion.fromRuntime();
-	private static final String MATCH_MESSAGE = "Required JVM version %s and found %s.";
-	private static final String NO_MATCH_MESSAGE = "Required JVM version %s but found %s.";
+	private static final JavaVersion JVM_VERSION = JavaVersion.getJavaVersion();
 
 	@Override
 	public ConditionOutcome getMatchOutcome(ConditionContext context,
 			AnnotatedTypeMetadata metadata) {
-
 		Map<String, Object> attributes = metadata
 				.getAnnotationAttributes(ConditionalOnJava.class.getName());
-
-		JavaVersion version = (JavaVersion) attributes.get("value");
 		Range range = (Range) attributes.get("range");
+		JavaVersion version = (JavaVersion) attributes.get("value");
+		return getMatchOutcome(range, JVM_VERSION, version);
+	}
 
-		ConditionOutcome match = ConditionOutcome.match(//
-				String.format(MATCH_MESSAGE, range.getMessage(version), JVM_VERSION));
-		ConditionOutcome noMatch = ConditionOutcome.noMatch(//
-				String.format(NO_MATCH_MESSAGE, range.getMessage(version), JVM_VERSION));
-
-		boolean equalOrBetter = JVM_VERSION.isEqualOrBetter(version);
+	protected ConditionOutcome getMatchOutcome(Range range, JavaVersion runningVersion,
+			JavaVersion version) {
+		boolean match = runningVersion.isWithin(range, version);
+		return new ConditionOutcome(match, getMessage(range, runningVersion, version));
+	}
 
-		switch (range) {
-		case OLDER_THAN:
-			return equalOrBetter ? noMatch : match;
-		case EQUAL_OR_NEWER:
-		default:
-			return equalOrBetter ? match : noMatch;
-		}
+	private String getMessage(Range range, JavaVersion runningVersion, JavaVersion version) {
+		String expected = String.format(range == Range.EQUAL_OR_NEWER ? "%s or newer"
+				: "older than %s", version);
+		return "Required JVM version " + expected + " found " + runningVersion;
 	}
 }

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

@@ -24,60 +24,97 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
+import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.iterableWithSize;
 import static org.junit.Assert.assertThat;
 
 /**
  * Tests for {@link ConditionalOnJava}.
- *
+ * 
  * @author Oliver Gierke
+ * @author Phillip Webb
  */
 public class ConditionalOnJavaTests {
 
 	private final AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
 
+	private final OnJavaCondition condition = new OnJavaCondition();
+
 	@Test
 	public void doesNotMatchIfBetterVersionIsRequired() {
-
-		this.context.register(Java9Required.class);
-		this.context.refresh();
-
+		registerAndRefresh(Java9Required.class);
 		assertPresent(false);
 	}
 
 	@Test
 	public void doesNotMatchIfLowerIsRequired() {
-
-		this.context.register(Java5Required.class);
-		this.context.refresh();
-
+		registerAndRefresh(Java5Required.class);
 		assertPresent(false);
 	}
 
 	@Test
 	public void matchesIfVersionIsInRange() {
+		registerAndRefresh(Java6Required.class);
+		assertPresent(true);
+	}
+
+	@Test
+	public void boundsTests() throws Exception {
+		testBounds(Range.EQUAL_OR_NEWER, JavaVersion.SEVEN, JavaVersion.SIX, true);
+		testBounds(Range.EQUAL_OR_NEWER, JavaVersion.SEVEN, JavaVersion.SEVEN, true);
+		testBounds(Range.EQUAL_OR_NEWER, JavaVersion.SEVEN, JavaVersion.EIGHT, false);
+		testBounds(Range.OLDER_THAN, JavaVersion.SEVEN, JavaVersion.SIX, false);
+		testBounds(Range.OLDER_THAN, JavaVersion.SEVEN, JavaVersion.SEVEN, false);
+		testBounds(Range.OLDER_THAN, JavaVersion.SEVEN, JavaVersion.EIGHT, true);
+	}
+
+	@Test
+	public void equalOrNewerMessage() throws Exception {
+		ConditionOutcome outcome = this.condition.getMatchOutcome(Range.EQUAL_OR_NEWER,
+				JavaVersion.SEVEN, JavaVersion.SIX);
+		assertThat(outcome.getMessage(), equalTo("Required JVM version "
+				+ "1.6 or newer found 1.7"));
+	}
+
+	@Test
+	public void olderThanMessage() throws Exception {
+		ConditionOutcome outcome = this.condition.getMatchOutcome(Range.OLDER_THAN,
+				JavaVersion.SEVEN, JavaVersion.SIX);
+		assertThat(outcome.getMessage(), equalTo("Required JVM version "
+				+ "older than 1.6 found 1.7"));
+	}
 
-		this.context.register(Java6Required.class);
+	private void testBounds(Range range, JavaVersion runningVersion, JavaVersion version,
+			boolean expected) {
+		ConditionOutcome outcome = this.condition.getMatchOutcome(range, runningVersion,
+				version);
+		assertThat(outcome.getMessage(), outcome.isMatch(), equalTo(expected));
+	}
+
+	private void registerAndRefresh(Class<?> annotatedClasses) {
+		this.context.register(annotatedClasses);
 		this.context.refresh();
+	}
 
-		assertPresent(true);
+	private void assertPresent(boolean expected) {
+		int expectedNumber = expected ? 1 : 0;
+		Matcher<Iterable<String>> matcher = iterableWithSize(expectedNumber);
+		assertThat(this.context.getBeansOfType(String.class).values(), is(matcher));
 	}
 
 	@Configuration
 	@ConditionalOnJava(JavaVersion.NINE)
 	static class Java9Required {
-
 		@Bean
 		String foo() {
 			return "foo";
 		}
 	}
 
 	@Configuration
-	@ConditionalOnJava(value = JavaVersion.SIX, range = Range.OLDER_THAN)
+	@ConditionalOnJava(range = Range.OLDER_THAN, value = JavaVersion.SIX)
 	static class Java5Required {
-
 		@Bean
 		String foo() {
 			return "foo";
@@ -87,18 +124,10 @@ String foo() {
 	@Configuration
 	@ConditionalOnJava(JavaVersion.SIX)
 	static class Java6Required {
-
 		@Bean
 		String foo() {
 			return "foo";
 		}
 	}
 
-	private void assertPresent(boolean expected) {
-
-		int expectedNumber = expected ? 1 : 0;
-		Matcher<Iterable<String>> matcher = iterableWithSize(expectedNumber);
-
-		assertThat(this.context.getBeansOfType(String.class).values(), is(matcher));
-	}
 }