openconverter.java

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

            }

	    if (annotatedConstrList.isEmpty())
		return "no constructor has @ConstructorProperties annotation";

            annotatedConstructors = newList();

            // Now check that all the annotated constructors are valid
            // and throw an exception if not.

            // First link the itemNames to their getter indexes.
            Map<String, Integer> getterMap = newMap();
            String[] itemNames = getItemNames();
            for (int i = 0; i < itemNames.length; i++)
                getterMap.put(itemNames[i], i);

            // Run through the constructors making the checks in the spec.
            // For each constructor, remember the correspondence between its
            // parameters and the items.  The int[] for a constructor says
            // what parameter index should get what item.  For example,
            // if element 0 is 2 then that means that item 0 in the
            // CompositeData goes to parameter 2 of the constructor.  If an
            // element is -1, that item isn't given to the constructor.
            // Also remember the set of properties in that constructor
            // so we can test unambiguity.
            Set<BitSet> getterIndexSets = newSet();
            for (Constructor constr : annotatedConstrList) {
                String[] propertyNames =
                    constr.getAnnotation(propertyNamesClass).value();

                Type[] paramTypes = constr.getGenericParameterTypes();
                if (paramTypes.length != propertyNames.length) {
                    final String msg =
                        "Number of constructor params does not match " +
                        "@ConstructorProperties annotation: " + constr;
                    throw new InvalidObjectException(msg);
                }

                // Work around bug 6710498 (really caused by 5041784):
                for (int i = 0; i < paramTypes.length; i++)
                    paramTypes[i] = fixType(paramTypes[i]);

                int[] paramIndexes = new int[getters.length];
                for (int i = 0; i < getters.length; i++)
                    paramIndexes[i] = -1;
                BitSet present = new BitSet();

                for (int i = 0; i < propertyNames.length; i++) {
                    String propertyName = propertyNames[i];
                    if (!getterMap.containsKey(propertyName)) {
                        String msg =
                            "@ConstructorProperties includes name " + propertyName +
                            " which does not correspond to a property";
                        for (String getterName : getterMap.keySet()) {
                            if (getterName.equalsIgnoreCase(propertyName)) {
                                msg += " (differs only in case from property " +
                                        getterName + ")";
                            }
                        }
                        msg += ": " + constr;
                        throw new InvalidObjectException(msg);
                    }
                    int getterIndex = getterMap.get(propertyName);
                    paramIndexes[getterIndex] = i;
                    if (present.get(getterIndex)) {
                        final String msg =
                            "@ConstructorProperties contains property " +
                            propertyName + " more than once: " + constr;
                        throw new InvalidObjectException(msg);
                    }
                    present.set(getterIndex);
                    Method getter = getters[getterIndex];
                    Type propertyType = getter.getGenericReturnType();
                    if (!propertyType.equals(paramTypes[i])) {
                        final String msg =
                            "@ConstructorProperties gives property " + propertyName +
                            " of type " + propertyType + " for parameter " +
                            " of type " + paramTypes[i] + ": " + constr;
                        throw new InvalidObjectException(msg);
                    }
                }

                if (!getterIndexSets.add(present)) {
                    final String msg =
                        "More than one constructor has a @ConstructorProperties " +
                        "annotation with this set of names: " +
                        Arrays.toString(propertyNames);
                    throw new InvalidObjectException(msg);
                }

                Constr c = new Constr(constr, paramIndexes, present);
                annotatedConstructors.add(c);
            }

            /* Check that no possible set of items could lead to an ambiguous
             * choice of constructor (spec requires this check).  For any
             * pair of constructors, their union would be the minimal
             * ambiguous set.  If this set itself corresponds to a constructor,
             * there is no ambiguity for that pair.  In the usual case, one
             * of the constructors is a superset of the other so the union is
             * just the bigger constuctor.
	     *
	     * The algorithm here is quadratic in the number of constructors
	     * with a @ConstructorProperties annotation.  Typically this corresponds
	     * to the number of versions of the class there have been.  Ten
	     * would already be a large number, so although it's probably
	     * possible to have an O(n lg n) algorithm it wouldn't be
	     * worth the complexity.
             */
            for (BitSet a : getterIndexSets) {
                boolean seen = false;
                for (BitSet b : getterIndexSets) {
                    if (a == b)
                        seen = true;
                    else if (seen) {
                        BitSet u = new BitSet();
                        u.or(a); u.or(b);
                        if (!getterIndexSets.contains(u)) {
                            Set<String> names = new TreeSet<String>();
                            for (int i = u.nextSetBit(0); i >= 0;
                                 i = u.nextSetBit(i+1))
                                names.add(itemNames[i]);
                            final String msg =
                                "Constructors with @ConstructorProperties annotation " +
                                " would be ambiguous for these items: " +
                                names;
                            throw new InvalidObjectException(msg);
                        }
                    }
                }
            }

	    return null; // success!
	}

        Object fromCompositeData(MXBeanLookup lookup, CompositeData cd,
                                 String[] itemNames,
                                 OpenConverter[] converters)
                throws InvalidObjectException {
            // The CompositeData might come from an earlier version where
            // not all the items were present.  We look for a constructor
            // that accepts just the items that are present.  Because of
            // the ambiguity check in applicable(), we know there must be
            // at most one maximally applicable constructor.
            CompositeType ct = cd.getCompositeType();
            BitSet present = new BitSet();
            for (int i = 0; i < itemNames.length; i++) {
                if (ct.getType(itemNames[i]) != null)
                    present.set(i);
            }

            Constr max = null;
            for (Constr constr : annotatedConstructors) {
                if (subset(constr.presentParams, present) &&
                        (max == null ||
                         subset(max.presentParams, constr.presentParams)))
                    max = constr;
            }

            if (max == null) {
                final String msg =
                    "No constructor has a @ConstructorProperties for this set of " +
                    "items: " + ct.keySet();
                throw new InvalidObjectException(msg);
            }

            Object[] params = new Object[max.presentParams.cardinality()];
            for (int i = 0; i < itemNames.length; i++) {
                if (!max.presentParams.get(i))
                    continue;
                Object openItem = cd.get(itemNames[i]);
                Object javaItem = converters[i].fromOpenValue(lookup, openItem);
                int index = max.paramIndexes[i];
                if (index >= 0)
                    params[index] = javaItem;
            }

	    try {
		return max.constructor.newInstance(params);
	    } catch (Exception e) {
		final String msg =
		    "Exception constructing " + getTargetClass().getName();
                throw invalidObjectException(msg, e);
	    }
        }

        private static boolean subset(BitSet sub, BitSet sup) {
            BitSet subcopy = (BitSet) sub.clone();
            subcopy.andNot(sup);
            return subcopy.isEmpty();
        }

        private static class Constr {
            final Constructor constructor;
            final int[] paramIndexes;
            final BitSet presentParams;
            Constr(Constructor constructor, int[] paramIndexes,
                   BitSet presentParams) {
                this.constructor = constructor;
                this.paramIndexes = paramIndexes;
                this.presentParams = presentParams;
            }
        }

        private List<Constr> annotatedConstructors;
    }

    /** Builder for when the target class is an interface and contains
	no methods other than getters.  Then we can make an instance
	using a dynamic proxy that forwards the getters to the source
	CompositeData.  */
    private static final class CompositeBuilderViaProxy
	    extends CompositeBuilder {

	CompositeBuilderViaProxy(Class targetClass, String[] itemNames) {
	    super(targetClass, itemNames);
	}

	String applicable(Method[] getters) {
	    Class targetClass = getTargetClass();
	    if (!targetClass.isInterface())
		return "not an interface";
            Set<Method> methods =
                newSet(Arrays.asList(targetClass.getMethods()));
            methods.removeAll(Arrays.asList(getters));
            /* If the interface has any methods left over, they better be
             * public methods that are already present in java.lang.Object.
             */
            String bad = null;
            for (Method m : methods) {
                String mname = m.getName();
                Class[] mparams = m.getParameterTypes();
                try {
                    Method om = Object.class.getMethod(mname, mparams);
                    if (!Modifier.isPublic(om.getModifiers()))
                        bad = mname;
                } catch (NoSuchMethodException e) {
                    bad = mname;
                }
                /* We don't catch SecurityException since it shouldn't
                 * happen for a method in Object and if it does we would
                 * like to know about it rather than mysteriously complaining.
                 */
            }
	    if (bad != null)
		return "contains methods other than getters (" + bad + ")";
	    return null; // success!
	}

	final Object fromCompositeData(MXBeanLookup lookup, CompositeData cd,
                                 String[] itemNames,
                                 OpenConverter[] converters) {
	    final Class targetClass = getTargetClass();
	    return
		Proxy.newProxyInstance(targetClass.getClassLoader(),
				       new Class[] {targetClass},
				       new CompositeDataInvocationHandler(cd));
	}
    }

    static InvalidObjectException invalidObjectException(String msg,
                                                         Throwable cause) {
        return EnvHelp.initCause(new InvalidObjectException(msg), cause);
    }

    static InvalidObjectException invalidObjectException(Throwable cause) {
        return invalidObjectException(cause.getMessage(), cause);
    }

    static OpenDataException openDataException(String msg, Throwable cause) {
        return EnvHelp.initCause(new OpenDataException(msg), cause);
    }

    static OpenDataException openDataException(Throwable cause) {
        return openDataException(cause.getMessage(), cause);
    }

    static void mustBeComparable(Class collection, Type element)
            throws OpenDataException {
        if (!(element instanceof Class)
            || !Comparable.class.isAssignableFrom((Class<?>) element)) {
            final String msg =
                "Parameter class " + element + " of " +
                collection.getName() + " does not implement " +
                Comparable.class.getName();
            throw new OpenDataException(msg);
        }
    }

    /**
     * Utility method to take a string and convert it to normal Java variable
     * name capitalization.  This normally means converting the first
     * character from upper case to lower case, but in the (unusual) special
     * case when there is more than one character and both the first and
     * second characters are upper case, we leave it alone.
     * <p>
     * Thus "FooBah" becomes "fooBah" and "X" becomes "x", but "URL" stays
     * as "URL".
     *
     * @param  name The string to be decapitalized.
     * @return  The decapitalized version of the string.
     */
    public static String decapitalize(String name) {
        if (name == null || name.length() == 0) {
            return name;
        }
        int offset1 = Character.offsetByCodePoints(name, 0, 1);
        // Should be name.offsetByCodePoints but 6242664 makes this fail
        if (offset1 < name.length() &&
                Character.isUpperCase(name.codePointAt(offset1)))
            return name;
        return name.substring(0, offset1).toLowerCase() +
               name.substring(offset1);
    }

    /**
     * Reverse operation for java.beans.Introspector.decapitalize.  For any s,
     * capitalize(decapitalize(s)).equals(s).  The reverse is not true:
     * e.g. capitalize("uRL") produces "URL" which is unchanged by
     * decapitalize.
     */
    static String capitalize(String name) {
        if (name == null || name.length() == 0)
            return name;
        int offset1 = name.offsetByCodePoints(0, 1);
        return name.substring(0, offset1).toUpperCase() +
               name.substring(offset1);
    }

    public static String propertyName(Method m) {
	String rest = null;
	String name = m.getName();
	if (name.startsWith("get"))
	    rest = name.substring(3);
	else if (name.startsWith("is") && m.getReturnType() == boolean.class)
	    rest = name.substring(2);
	if (rest == null || rest.length() == 0
	    || m.getParameterTypes().length > 0
	    || m.getReturnType() == void.class
	    || name.equals("getClass"))
	    return null;
	return rest;
    }

    private static String typeName(Type t) {
        if (t instanceof Class<?>) {
            Class<?> c = (Class<?>) t;
            if (c.isArray())
                return typeName(c.getComponentType()) + "[]";
            else
                return c.getName();
        }
        return t.toString();
    }

    // Work around for bug 5041784, where types like String[] are sometimes
    // represented as GenericArrayType instead of Class.
    private static Type fixType(Type t) {
        if (!(t instanceof GenericArrayType))
            return t;
        GenericArrayType gat = (GenericArrayType) t;
        Type ultimate = ultimateComponentType(gat);
        if (!(ultimate instanceof Class<?>))
            return t;
        Class<?> component = (Class<?>) fixType(gat.getGenericComponentType());
        return Array.newInstance(component, 0).getClass();
    }

    private static Type ultimateComponentType(GenericArrayType gat) {
        Type component = gat.getGenericComponentType();
        if (component instanceof GenericArrayType)
            return ultimateComponentType((GenericArrayType) component);
        else
            return component;
    }

    private final static Map<Type, Type> inProgress = newIdentityHashMap();
    // really an IdentityHashSet but that doesn't exist
}