# HG changeset patch # User alanb # Date 1259004376 0 # Node ID 9591511c1d881915ed435addf3678ff55459625a # Parent 7c352d15334c9f175fa18daaa60a7e545549d873 6888171: JMX Monitor API should not require JavaBeans to be present Reviewed-by: emcmanus diff -r 7c352d15334c -r 9591511c1d88 jdk/src/share/classes/com/sun/jmx/mbeanserver/Introspector.java --- a/jdk/src/share/classes/com/sun/jmx/mbeanserver/Introspector.java Mon Nov 23 13:57:52 2009 -0500 +++ b/jdk/src/share/classes/com/sun/jmx/mbeanserver/Introspector.java Mon Nov 23 19:26:16 2009 +0000 @@ -26,6 +26,7 @@ package com.sun.jmx.mbeanserver; import java.lang.annotation.Annotation; +import java.lang.ref.SoftReference; import java.lang.reflect.AnnotatedElement; import java.lang.reflect.Constructor; import java.lang.reflect.Method; @@ -33,8 +34,13 @@ import java.lang.reflect.Proxy; import java.lang.reflect.UndeclaredThrowableException; import java.util.Arrays; +import java.util.Collections; import java.util.HashMap; +import java.util.List; +import java.util.LinkedList; +import java.util.Locale; import java.util.Map; +import java.util.WeakHashMap; import javax.management.Descriptor; import javax.management.DescriptorKey; @@ -506,11 +512,25 @@ } else { // Java Beans introspection // - BeanInfo bi = java.beans.Introspector.getBeanInfo(complex.getClass()); - PropertyDescriptor[] pds = bi.getPropertyDescriptors(); - for (PropertyDescriptor pd : pds) - if (pd.getName().equals(element)) - return pd.getReadMethod().invoke(complex); + Class clazz = complex.getClass(); + Method readMethod = null; + if (BeansHelper.isAvailable()) { + Object bi = BeansHelper.getBeanInfo(clazz); + Object[] pds = BeansHelper.getPropertyDescriptors(bi); + for (Object pd: pds) { + if (BeansHelper.getPropertyName(pd).equals(element)) { + readMethod = BeansHelper.getReadMethod(pd); + break; + } + } + } else { + // Java Beans not available so use simple introspection + // to locate method + readMethod = SimpleIntrospector.getReadMethod(clazz, element); + } + if (readMethod != null) + return readMethod.invoke(complex); + throw new AttributeNotFoundException( "Could not find the getter method for the property " + element + " using the Java Beans introspector"); @@ -524,4 +544,235 @@ new AttributeNotFoundException(e.getMessage()), e); } } + + /** + * A simple introspector that uses reflection to analyze a class and + * identify its "getter" methods. This class is intended for use only when + * Java Beans is not present (which implies that there isn't explicit + * information about the bean available). + */ + private static class SimpleIntrospector { + private SimpleIntrospector() { } + + private static final String GET_METHOD_PREFIX = "get"; + private static final String IS_METHOD_PREFIX = "is"; + + // cache to avoid repeated lookups + private static final Map,SoftReference>> cache = + Collections.synchronizedMap( + new WeakHashMap,SoftReference>> ()); + + /** + * Returns the list of methods cached for the given class, or {@code null} + * if not cached. + */ + private static List getCachedMethods(Class clazz) { + // return cached methods if possible + SoftReference> ref = cache.get(clazz); + if (ref != null) { + List cached = ref.get(); + if (cached != null) + return cached; + } + return null; + } + + /** + * Returns {@code true} if the given method is a "getter" method (where + * "getter" method is a public method of the form getXXX or "boolean + * isXXX") + */ + static boolean isReadMethod(Method method) { + // ignore static methods + int modifiers = method.getModifiers(); + if (Modifier.isStatic(modifiers)) + return false; + + String name = method.getName(); + Class[] paramTypes = method.getParameterTypes(); + int paramCount = paramTypes.length; + + if (paramCount == 0 && name.length() > 2) { + // boolean isXXX() + if (name.startsWith(IS_METHOD_PREFIX)) + return (method.getReturnType() == boolean.class); + // getXXX() + if (name.length() > 3 && name.startsWith(GET_METHOD_PREFIX)) + return (method.getReturnType() != void.class); + } + return false; + } + + /** + * Returns the list of "getter" methods for the given class. The list + * is ordered so that isXXX methods appear before getXXX methods - this + * is for compatability with the JavaBeans Introspector. + */ + static List getReadMethods(Class clazz) { + // return cached result if available + List cachedResult = getCachedMethods(clazz); + if (cachedResult != null) + return cachedResult; + + // get list of public methods, filtering out methods that have + // been overridden to return a more specific type. + List methods = + StandardMBeanIntrospector.getInstance().getMethods(clazz); + methods = MBeanAnalyzer.eliminateCovariantMethods(methods); + + // filter out the non-getter methods + List result = new LinkedList(); + for (Method m: methods) { + if (isReadMethod(m)) { + // favor isXXX over getXXX + if (m.getName().startsWith(IS_METHOD_PREFIX)) { + result.add(0, m); + } else { + result.add(m); + } + } + } + + // add result to cache + cache.put(clazz, new SoftReference>(result)); + + return result; + } + + /** + * Returns the "getter" to read the given property from the given class or + * {@code null} if no method is found. + */ + static Method getReadMethod(Class clazz, String property) { + // first character in uppercase (compatability with JavaBeans) + property = property.substring(0, 1).toUpperCase(Locale.ENGLISH) + + property.substring(1); + String getMethod = GET_METHOD_PREFIX + property; + String isMethod = IS_METHOD_PREFIX + property; + for (Method m: getReadMethods(clazz)) { + String name = m.getName(); + if (name.equals(isMethod) || name.equals(getMethod)) { + return m; + } + } + return null; + } + } + + /** + * A class that provides access to the JavaBeans Introspector and + * PropertyDescriptors without creating a static dependency on java.beans. + */ + private static class BeansHelper { + private static final Class introspectorClass = + getClass("java.beans.Introspector"); + private static final Class beanInfoClass = + (introspectorClass == null) ? null : getClass("java.beans.BeanInfo"); + private static final Class getPropertyDescriptorClass = + (beanInfoClass == null) ? null : getClass("java.beans.PropertyDescriptor"); + + private static final Method getBeanInfo = + getMethod(introspectorClass, "getBeanInfo", Class.class); + private static final Method getPropertyDescriptors = + getMethod(beanInfoClass, "getPropertyDescriptors"); + private static final Method getPropertyName = + getMethod(getPropertyDescriptorClass, "getName"); + private static final Method getReadMethod = + getMethod(getPropertyDescriptorClass, "getReadMethod"); + + private static Class getClass(String name) { + try { + return Class.forName(name, true, null); + } catch (ClassNotFoundException e) { + return null; + } + } + private static Method getMethod(Class clazz, + String name, + Class... paramTypes) + { + if (clazz != null) { + try { + return clazz.getMethod(name, paramTypes); + } catch (NoSuchMethodException e) { + throw new AssertionError(e); + } + } else { + return null; + } + } + + private BeansHelper() { } + + /** + * Returns {@code true} if java.beans is available. + */ + static boolean isAvailable() { + return introspectorClass != null; + } + + /** + * Invokes java.beans.Introspector.getBeanInfo(Class) + */ + static Object getBeanInfo(Class clazz) throws Exception { + try { + return getBeanInfo.invoke(null, clazz); + } catch (InvocationTargetException e) { + Throwable cause = e.getCause(); + if (cause instanceof Exception) + throw (Exception)cause; + throw new AssertionError(e); + } catch (IllegalAccessException iae) { + throw new AssertionError(iae); + } + } + + /** + * Invokes java.beans.BeanInfo.getPropertyDescriptors() + */ + static Object[] getPropertyDescriptors(Object bi) { + try { + return (Object[])getPropertyDescriptors.invoke(bi); + } catch (InvocationTargetException e) { + Throwable cause = e.getCause(); + if (cause instanceof RuntimeException) + throw (RuntimeException)cause; + throw new AssertionError(e); + } catch (IllegalAccessException iae) { + throw new AssertionError(iae); + } + } + + /** + * Invokes java.beans.PropertyDescriptor.getName() + */ + static String getPropertyName(Object pd) { + try { + return (String)getPropertyName.invoke(pd); + } catch (InvocationTargetException e) { + Throwable cause = e.getCause(); + if (cause instanceof RuntimeException) + throw (RuntimeException)cause; + throw new AssertionError(e); + } catch (IllegalAccessException iae) { + throw new AssertionError(iae); + } + } + + /** + * Invokes java.beans.PropertyDescriptor.getReadMethod() + */ + static Method getReadMethod(Object pd) { + try { + return (Method)getReadMethod.invoke(pd); + } catch (InvocationTargetException e) { + Throwable cause = e.getCause(); + if (cause instanceof RuntimeException) + throw (RuntimeException)cause; + throw new AssertionError(e); + } catch (IllegalAccessException iae) { + throw new AssertionError(iae); + } + } + } } diff -r 7c352d15334c -r 9591511c1d88 jdk/src/share/classes/com/sun/jmx/mbeanserver/MBeanIntrospector.java --- a/jdk/src/share/classes/com/sun/jmx/mbeanserver/MBeanIntrospector.java Mon Nov 23 13:57:52 2009 -0500 +++ b/jdk/src/share/classes/com/sun/jmx/mbeanserver/MBeanIntrospector.java Mon Nov 23 19:26:16 2009 +0000 @@ -175,7 +175,7 @@ /** * Get the methods to be analyzed to build the MBean interface. */ - List getMethods(final Class mbeanType) throws Exception { + List getMethods(final Class mbeanType) { return Arrays.asList(mbeanType.getMethods()); }