mbeanintrospector.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

     * Invoke the given setter on the given target with the given argument
     * and cookie.  Wrap exceptions appropriately.
     */
    /* If the value is of the wrong type for the method we are about to
     * invoke, we are supposed to throw an InvalidAttributeValueException.
     * Rather than making the check always, we invoke the method, then
     * if it throws an exception we check the type to see if that was
     * what caused the exception.  The assumption is that an exception
     * from an invalid type will arise before any user method is ever
     * called (either in reflection or in OpenConverter).
     */
    final void invokeSetter(String name, M setter, Object target, Object arg,
            Object cookie)
            throws MBeanException, ReflectionException,
            InvalidAttributeValueException {
        try {
            invokeM2(setter, target, new Object[] {arg}, cookie);
        } catch (IllegalAccessException e) {
            throw new ReflectionException(e, e.toString());
        } catch (RuntimeException e) {
            maybeInvalidParameter(name, setter, arg, cookie);
            throw e;
        } catch (InvocationTargetException e) {
            maybeInvalidParameter(name, setter, arg, cookie);
            unwrapInvocationTargetException(e);
        }
    }
    
    private void maybeInvalidParameter(String name, M setter, Object arg,
            Object cookie)
            throws InvalidAttributeValueException {
        if (!validParameter(setter, arg, 0, cookie)) {
            final String msg =
                    "Invalid value for attribute " + name + ": " + arg;
            throw new InvalidAttributeValueException(msg);
        }
    }
    
    static boolean isValidParameter(Method m, Object value, int paramNo) {
        Class<?> c = m.getParameterTypes()[paramNo];
        try {
            // Following is expensive but we only call this method to determine
            // if an exception is due to an incompatible parameter type.
            // Plain old c.isInstance doesn't work for primitive types.
            Object a = Array.newInstance(c, 1);
            Array.set(a, 0, value);
            return true;
        } catch (IllegalArgumentException e) {
            return false;
        }
    }
    
    private static void
            unwrapInvocationTargetException(InvocationTargetException e)
            throws MBeanException {
        Throwable t = e.getCause();
        if (t instanceof RuntimeException)
            throw (RuntimeException) t;
        else if (t instanceof Error)
            throw (Error) t;
        else
            throw new MBeanException((Exception) t,
                    (t == null ? null : t.toString()));
    }
    
    /** A visitor that constructs the per-interface MBeanInfo. */
    private class MBeanInfoMaker implements MBeanAnalyzer.MBeanVisitor<M> {
        
        public void visitAttribute(String attributeName,
                M getter,
                M setter) {
            MBeanAttributeInfo mbai =
                    getMBeanAttributeInfo(attributeName, getter, setter);
            
            attrs.add(mbai);
        }
        
        public void visitOperation(String operationName,
                M operation) {
            MBeanOperationInfo mboi =
                    getMBeanOperationInfo(operationName, operation);
            
            ops.add(mboi);
        }
        
        /** Make an MBeanInfo based on the attributes and operations
         *  found in the interface. */
        MBeanInfo makeMBeanInfo(Class<?> mbeanInterface,
                String description) {
            final MBeanAttributeInfo[] attrArray =
                    attrs.toArray(new MBeanAttributeInfo[0]);
            final MBeanOperationInfo[] opArray =
                    ops.toArray(new MBeanOperationInfo[0]);
            final String interfaceClassName =
                    "interfaceClassName=" + mbeanInterface.getName();
            final Descriptor interfDescriptor =
                    new ImmutableDescriptor(interfaceClassName);
            final Descriptor mbeanDescriptor = getBasicMBeanDescriptor();
            final Descriptor annotatedDescriptor =
                    Introspector.descriptorForElement(mbeanInterface);
            final Descriptor descriptor =
                    DescriptorCache.getInstance().union(interfDescriptor,
                    mbeanDescriptor,
                    annotatedDescriptor);
            
            return new MBeanInfo(mbeanInterface.getName(),
                    description,
                    attrArray,
                    null,
                    opArray,
                    null,
                    descriptor);
        }
        
        private final List<MBeanAttributeInfo> attrs = newList();
        private final List<MBeanOperationInfo> ops = newList();
    }
    
    /*
     * Looking up the MBeanInfo for a given base class (implementation class)
     * is complicated by the fact that we may use the same base class with
     * several different explicit MBean interfaces via the
     * javax.management.StandardMBean class.  It is further complicated
     * by the fact that we have to be careful not to retain a strong reference
     * to any Class object for fear we would prevent a ClassLoader from being
     * garbage-collected.  So we have a first lookup from the base class
     * to a map for each interface that base class might specify giving
     * the MBeanInfo constructed for that base class and interface.
     */
    static class MBeanInfoMap
            extends WeakHashMap<Class<?>, WeakHashMap<Class<?>, MBeanInfo>> {
    }
    
    /**
     * Return the MBeanInfo for the given resource, based on the given
     * per-interface data.
     */
    final MBeanInfo getMBeanInfo(Object resource, PerInterface<M> perInterface) {
        MBeanInfo mbi =
                getClassMBeanInfo(resource.getClass(), perInterface);
        MBeanNotificationInfo[] notifs = findNotifications(resource);
        if (notifs == null || notifs.length == 0)
            return mbi;
        else {
            return new MBeanInfo(mbi.getClassName(),
                    mbi.getDescription(),
                    mbi.getAttributes(),
                    mbi.getConstructors(),
                    mbi.getOperations(),
                    notifs,
                    mbi.getDescriptor());
        }
    }
    
    /**
     * Return the basic MBeanInfo for resources of the given class and
     * per-interface data.  This MBeanInfo might not be the final MBeanInfo
     * for instances of the class, because if the class is a
     * NotificationBroadcaster then each instance gets to decide what
     * MBeanNotificationInfo[] to put in its own MBeanInfo.
     */
    final MBeanInfo getClassMBeanInfo(Class<?> resourceClass,
            PerInterface<M> perInterface) {
        MBeanInfoMap map = getMBeanInfoMap();
        synchronized (map) {
            WeakHashMap<Class<?>, MBeanInfo> intfMap = map.get(resourceClass);
            if (intfMap == null) {
                intfMap = new WeakHashMap<Class<?>, MBeanInfo>();
                map.put(resourceClass, intfMap);
            }
            Class<?> intfClass = perInterface.getMBeanInterface();
            MBeanInfo mbi = intfMap.get(intfClass);
            if (mbi == null) {
                MBeanInfo imbi = perInterface.getMBeanInfo();
                Descriptor descriptor =
                        ImmutableDescriptor.union(imbi.getDescriptor(),
                        getMBeanDescriptor(resourceClass));
                mbi = new MBeanInfo(resourceClass.getName(),
                        imbi.getDescription(),
                        imbi.getAttributes(),
                        findConstructors(resourceClass),
                        imbi.getOperations(),
                        (MBeanNotificationInfo[]) null,
                        descriptor);
                intfMap.put(intfClass, mbi);
            }
            return mbi;
        }
    }
    
    static MBeanNotificationInfo[] findNotifications(Object moi) {
        if (!(moi instanceof NotificationBroadcaster))
            return null;
        MBeanNotificationInfo[] mbn =
                ((NotificationBroadcaster) moi).getNotificationInfo();
        if (mbn == null)
            return null;
        MBeanNotificationInfo[] result =
                new MBeanNotificationInfo[mbn.length];
        for (int i = 0; i < mbn.length; i++) {
            MBeanNotificationInfo ni = mbn[i];
            if (ni.getClass() != MBeanNotificationInfo.class)
                ni = (MBeanNotificationInfo) ni.clone();
            result[i] = ni;
        }
        return result;
    }
    
    private static MBeanConstructorInfo[] findConstructors(Class<?> c) {
        Constructor[] cons = c.getConstructors();
        MBeanConstructorInfo[] mbc = new MBeanConstructorInfo[cons.length];
        for (int i = 0; i < cons.length; i++) {
            final String descr = "Public constructor of the MBean";
            mbc[i] = new MBeanConstructorInfo(descr, cons[i]);
        }
        return mbc;
    }
    
}