revised Java 6 checks to test for the presence of specific Java 6 interfaces/classes only

org.springframework.context/src/main/java/org/springframework/jmx/access/MBeanClientInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2009 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.
@@ -54,7 +54,6 @@ import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.InitializingBean;
-import org.springframework.core.JdkVersion;
 import org.springframework.jmx.support.JmxUtils;
 import org.springframework.jmx.support.ObjectNameManager;
 import org.springframework.util.ClassUtils;
@@ -258,7 +257,7 @@ public class MBeanClientInterceptor
 			if (this.useStrictCasing) {
 				// Use the JDK's own MBeanServerInvocationHandler,
 				// in particular for native MXBean support on Java 6.
-				if (JdkVersion.isAtLeastJava16()) {
+				if (JmxUtils.isMXBeanSupportAvailable()) {
 					this.invocationHandler =
 							new MBeanServerInvocationHandler(this.serverToUse, this.objectName,
 									(this.managementInterface != null && JMX.isMXBeanInterface(this.managementInterface)));

org.springframework.context/src/main/java/org/springframework/jmx/support/JmxUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2009 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.
@@ -303,7 +303,7 @@ public abstract class JmxUtils {
 		for (Class iface : implementedInterfaces) {
 			boolean isMxBean = iface.getName().endsWith(MXBEAN_SUFFIX);
 			if (mxBeanAnnotationAvailable) {
-				Boolean checkResult = MXBeanChecker.hasMXBeanAnnotation(iface);
+				Boolean checkResult = MXBeanChecker.evaluateMXBeanAnnotation(iface);
 				if (checkResult != null) {
 					isMxBean = checkResult;
 				}
@@ -315,13 +315,22 @@ public abstract class JmxUtils {
 		return getMXBeanInterface(clazz.getSuperclass());
 	}
 
+	/**
+	 * Check whether MXBean support is available, i.e. whether we're running
+	 * on Java 6 or above.
+	 * @return <code>true</code> if available; <code>false</code> otherwise
+	 */
+	public static boolean isMXBeanSupportAvailable() {
+		return mxBeanAnnotationAvailable;
+	}
+
 
 	/**
 	 * Inner class to avoid a Java 6 dependency.
 	 */
 	private static class MXBeanChecker {
 
-		public static Boolean hasMXBeanAnnotation(Class<?> iface) {
+		public static Boolean evaluateMXBeanAnnotation(Class<?> iface) {
 			MXBean mxBean = iface.getAnnotation(MXBean.class);
 			return (mxBean != null ? mxBean.value() : null);
 		}

org.springframework.core/src/main/java/org/springframework/core/CollectionFactory.java

@@ -26,8 +26,6 @@ import java.util.LinkedHashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import java.util.NavigableMap;
-import java.util.NavigableSet;
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
@@ -36,6 +34,7 @@ import java.util.TreeSet;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArraySet;
 
+import org.springframework.util.ClassUtils;
 import org.springframework.util.LinkedCaseInsensitiveMap;
 
 /**
@@ -53,21 +52,34 @@ import org.springframework.util.LinkedCaseInsensitiveMap;
  */
 public abstract class CollectionFactory {
 
+	private static final String NAVIGABLE_SET_CLASS_NAME = "java.util.NavigableSet";
+
+	private static final String NAVIGABLE_MAP_CLASS_NAME = "java.util.NavigableMap";
+
 	private static final Set<Class> approximableCollectionTypes = new HashSet<Class>(10);
 
 	private static final Set<Class> approximableMapTypes = new HashSet<Class>(6);
 
+
 	static {
+		// Standard collection interfaces
 		approximableCollectionTypes.add(Collection.class);
 		approximableCollectionTypes.add(List.class);
 		approximableCollectionTypes.add(Set.class);
 		approximableCollectionTypes.add(SortedSet.class);
 		approximableMapTypes.add(Map.class);
 		approximableMapTypes.add(SortedMap.class);
-		if (JdkVersion.isAtLeastJava16()) {
+
-			approximableCollectionTypes.add(NavigableSet.class);
+		// New Java 6 collection interfaces
-			approximableMapTypes.add(NavigableMap.class);
+		try {
+			approximableCollectionTypes.add(ClassUtils.forName(NAVIGABLE_SET_CLASS_NAME, CollectionFactory.class.getClassLoader()));
+			approximableMapTypes.add(ClassUtils.forName(NAVIGABLE_MAP_CLASS_NAME, CollectionFactory.class.getClassLoader()));
 		}
+		catch (ClassNotFoundException ex) {
+			// not running on Java 6 or above...
+		}
+
+		// Common concrete collection classes
 		approximableCollectionTypes.add(ArrayList.class);
 		approximableCollectionTypes.add(LinkedList.class);
 		approximableCollectionTypes.add(HashSet.class);
@@ -78,6 +90,7 @@ public abstract class CollectionFactory {
 		approximableMapTypes.add(TreeMap.class);
 	}
 
+
 	/**
 	 * Create a linked Set if possible: This implementation always
 	 * creates a {@link java.util.LinkedHashSet}, since Spring 2.5

org.springframework.core/src/main/java/org/springframework/core/JdkVersion.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2009 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.
@@ -17,11 +17,11 @@
 package org.springframework.core;
 
 /**
- * Internal helper class used to find the Java/JDK version
+ * Internal helper class used to find the Java/JVM version
  * that Spring is operating on, to allow for automatically
  * adapting to the present platform's capabilities.
  *
- * <p>Note that Spring requires JVM 1.4 or higher, as of Spring 2.5.
+ * <p>Note that Spring requires JVM 1.5 or higher, as of Spring 3.0.
  *
  * @author Rod Johnson
  * @author Juergen Hoeller
@@ -62,10 +62,10 @@ public abstract class JdkVersion {
 	static {
 		javaVersion = System.getProperty("java.version");
 		// version String should look like "1.4.2_10"
-		if (javaVersion.indexOf("1.7.") != -1) {
+		if (javaVersion.contains("1.7.")) {
 			majorJavaVersion = JAVA_17;
 		}
-		else if (javaVersion.indexOf("1.6.") != -1) {
+		else if (javaVersion.contains("1.6.")) {
 			majorJavaVersion = JAVA_16;
 		}
 		else {
@@ -99,6 +99,7 @@ public abstract class JdkVersion {
 		return majorJavaVersion;
 	}
 
+
 	/**
 	 * Convenience method to determine if the current JVM is at least Java 1.4.
 	 * @return <code>true</code> if the current JVM is at least Java 1.4
@@ -133,12 +134,15 @@ public abstract class JdkVersion {
 	 * Convenience method to determine if the current JVM is at least
 	 * Java 1.6 (Java 6).
 	 * @return <code>true</code> if the current JVM is at least Java 1.6
+	 * @deprecated as of Spring 3.0, in favor of reflective checks for
+	 * the specific Java 1.6 classes of interest
 	 * @see #getMajorJavaVersion()
 	 * @see #JAVA_16
 	 * @see #JAVA_17
 	 */
+	@Deprecated
 	public static boolean isAtLeastJava16() {
-		return getMajorJavaVersion() >= JAVA_16;
+		return (majorJavaVersion >= JAVA_16);
 	}
 
 }