introspector.java

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

    }

    /**
     * Get the MBean interface implemented by a JMX Standard
     * MBean class. This method is only called by the legacy
     * code in "com.sun.management.jmx".
     *
     * @param baseClass The class to be tested.
     *
     * @return The MBean interface implemented by the MBean.
     *         Return <code>null</code> if the MBean is a DynamicMBean,
     *         or if no MBean interface is found.
     */
    public static Class getMBeanInterface(Class baseClass) {
        // Check if the given class implements the MBean interface
        // or the Dynamic MBean interface
        if (isDynamic(baseClass)) return null;
        try {
            return getStandardMBeanInterface(baseClass);
        } catch (NotCompliantMBeanException e) {
            return null;
        }
    }

    /**
     * Get the MBean interface implemented by a JMX Standard MBean class.
     *
     * @param baseClass The class to be tested.
     *
     * @return The MBean interface implemented by the Standard MBean.
     *
     * @throws NotCompliantMBeanException The specified class is
     * not a JMX compliant Standard MBean.
     */
    public static Class getStandardMBeanInterface(Class baseClass)
        throws NotCompliantMBeanException {
        Class current = baseClass;
        Class mbeanInterface = null;
        while (current != null) {
            mbeanInterface =
                findMBeanInterface(current, current.getName());
            if (mbeanInterface != null) break;
            current = current.getSuperclass();
        }
        if (mbeanInterface != null) {
            return mbeanInterface;
        } else {
            final String msg =
                "Class " + baseClass.getName() +
                " is not a JMX compliant Standard MBean";
            throw new NotCompliantMBeanException(msg);
        }
    }

    /**
     * Get the MXBean interface implemented by a JMX MXBean class.
     *
     * @param baseClass The class to be tested.
     *
     * @return The MXBean interface implemented by the MXBean.
     *
     * @throws NotCompliantMBeanException The specified class is
     * not a JMX compliant MXBean.
     */
    public static Class getMXBeanInterface(Class baseClass)
        throws NotCompliantMBeanException {
        try {
            return MXBeanSupport.findMXBeanInterface(baseClass);
        } catch (Exception e) {
            throw throwException(baseClass,e);
        }
    }

    /*
     * ------------------------------------------
     *  PRIVATE METHODS
     * ------------------------------------------
     */
    

    /**
     * Try to find the MBean interface corresponding to the class aName 
     * - i.e. <i>aName</i>MBean, from within aClass and its superclasses.
     **/
    private static Class findMBeanInterface(Class aClass, String aName) {
	Class current = aClass;
	while (current != null) {
	    final Class[] interfaces = current.getInterfaces();   
	    final int len = interfaces.length;
	    for (int i=0;i<len;i++)  {	     
		final Class inter = 
		    implementsMBean(interfaces[i], aName);
		if (inter != null) return inter;
	    }
	    current = current.getSuperclass();
	}
	return null;     
    }
    
    public static Descriptor descriptorForElement(final AnnotatedElement elmt) {
        if (elmt == null)
            return ImmutableDescriptor.EMPTY_DESCRIPTOR;
        final Annotation[] annots = elmt.getAnnotations();
        return descriptorForAnnotations(annots);
    }
    
    public static Descriptor descriptorForAnnotations(Annotation[] annots) {
        if (annots.length == 0)
            return ImmutableDescriptor.EMPTY_DESCRIPTOR;
        Map<String, Object> descriptorMap = new HashMap<String, Object>();
        for (Annotation a : annots) {
            Class<? extends Annotation> c = a.annotationType();
            Method[] elements = c.getMethods();
            for (Method element : elements) {
                DescriptorKey key = element.getAnnotation(DescriptorKey.class);
                if (key != null) {
                    String name = key.value();
                    Object value;
                    try {
                        value = element.invoke(a);
                    } catch (RuntimeException e) { 
                        // we don't expect this - except for possibly
                        // security exceptions? 
                        // RuntimeExceptions shouldn't be "UndeclaredThrowable".
                        // anyway...
                        //
                        throw e;
                    } catch (Exception e) {
                        // we don't expect this
                        throw new UndeclaredThrowableException(e);
                    }
                    value = annotationToField(value);
                    Object oldValue = descriptorMap.put(name, value);
                    if (oldValue != null && !equals(oldValue, value)) {
                        final String msg =
                            "Inconsistent values for descriptor field " + name +
                            " from annotations: " + value + " :: " + oldValue;
                        throw new IllegalArgumentException(msg);
                    }
                }
            }
        }
        
        if (descriptorMap.isEmpty())
            return ImmutableDescriptor.EMPTY_DESCRIPTOR;
        else
            return new ImmutableDescriptor(descriptorMap);
    }
    
    /**
     * Throws a NotCompliantMBeanException or a SecurityException.
     * @param notCompliant the class which was under examination
     * @param cause the raeson why NotCompliantMBeanException should
     *        be thrown.
     * @return nothing - this method always throw an exception.
     *         The return type makes it possible to write
     *         <pre> throw throwException(clazz,cause); </pre>
     * @throws SecurityException - if cause is a SecurityException
     * @throws NotCompliantMBeanException otherwise.
     **/
    static NotCompliantMBeanException throwException(Class<?> notCompliant,
            Throwable cause) 
            throws NotCompliantMBeanException, SecurityException {
        if (cause instanceof SecurityException) 
            throw (SecurityException) cause;
        if (cause instanceof NotCompliantMBeanException)
            throw (NotCompliantMBeanException)cause;
        final String classname = 
                (notCompliant==null)?"null class":notCompliant.getName();
        final String reason = 
                (cause==null)?"Not compliant":cause.getMessage();
        final NotCompliantMBeanException res = 
                new NotCompliantMBeanException(classname+": "+reason);
        res.initCause(cause);
        throw res;
    }

    // Convert a value from an annotation element to a descriptor field value
    // E.g. with @interface Foo {class value()} an annotation @Foo(String.class)
    // will produce a Descriptor field value "java.lang.String"
    private static Object annotationToField(Object x) {
        // An annotation element cannot have a null value but never mind
        if (x == null)
            return null;
        if (x instanceof Number || x instanceof String ||
                x instanceof Character || x instanceof Boolean ||
                x instanceof String[])
            return x;
        // Remaining possibilities: array of primitive (e.g. int[]),
        // enum, class, array of enum or class.
        Class<?> c = x.getClass();
        if (c.isArray()) {
            if (c.getComponentType().isPrimitive())
                return x;
            Object[] xx = (Object[]) x;
            String[] ss = new String[xx.length];
            for (int i = 0; i < xx.length; i++)
                ss[i] = (String) annotationToField(xx[i]);
            return ss;
        }
        if (x instanceof Class)
            return ((Class<?>) x).getName();
        if (x instanceof Enum)
            return ((Enum) x).name();
        // The only other possibility is that the value is another
        // annotation, or that the language has evolved since this code
        // was written.  We don't allow for either of those currently.
        throw new IllegalArgumentException("Illegal type for annotation " +
                "element: " + x.getClass().getName());
    }
    
    // This must be consistent with the check for duplicate field values in
    // ImmutableDescriptor.union.  But we don't expect to be called very
    // often so this inefficient check should be enough.
    private static boolean equals(Object x, Object y) {
        return Arrays.deepEquals(new Object[] {x}, new Object[] {y});
    }

    /**
     * Returns the XXMBean interface or null if no such interface exists
     *
     * @param c The interface to be tested
     * @param clName The name of the class implementing this interface
     */
    private static Class implementsMBean(Class c, String clName) {
        String clMBeanName = clName + "MBean";
	if (c.getName().equals(clMBeanName)) {
	    return c;
	}   
	Class current = c;
	Class[] interfaces = c.getInterfaces();
	for (int i = 0;i < interfaces.length; i++) {
            if (interfaces[i].getName().equals(clMBeanName))
                return interfaces[i];
	}
	
	return null;
    }
}