applicationcontextmigratorutil.java

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                put((String)entry.getKey(), entry.getValue());
            }
        }
        
        @Override
        public boolean containsKey(Object key) {
            return userMap.containsKey(key);
        }

        @Override
        public boolean containsValue(Object value) {
            return userMap.containsValue(value);
        }

        @Override
        public Set entrySet() {
            return new ApplicationPropertyMapEntrySet(userMap.entrySet(), mepCtx);
        }

        @Override
        public Object get(Object key) {
            // WARNING:  there's no real guarantee that the reason a migrator is getting
            // a property is due to it being put on the MessageContext.
            // We would therefore be setting scope for a property that never actually makes
            // its way into the messageContext.
            Object obj = userMap.get(key);
            if (obj != null) {
                mepCtx.setScope((String)key, Scope.APPLICATION);
            }
            return obj;
        }

        @Override
        public boolean isEmpty() {
            return userMap.isEmpty();
        }

        @Override
        public Set keySet() {
            return userMap.keySet();
        }

        @Override
        public Object remove(Object key) {
            return userMap.remove(key);
        }

        @Override
        public int size() {
            return userMap.size();
        }

        @Override
        public Collection values() {
            return userMap.values();
        }
        
        private class ApplicationPropertyMapEntrySet extends AbstractSet {

            Set containedSet;
            MEPContext mepCtx;
            
            public ApplicationPropertyMapEntrySet(Set set, MEPContext mepCtx) {
                containedSet = set;
                this.mepCtx = mepCtx;
            }
            
            @Override
            public EntrySetIterator iterator() {
                return new EntrySetIterator(containedSet.iterator(), mepCtx);
            }

            @Override
            public int size() {
                return containedSet.size();
            }
            
        }
        
        private class EntrySetIterator implements Iterator {
            
            private Iterator containedIterator;
            private MEPContext mepCtx;
            
            private EntrySetIterator(Iterator containedIterator, MEPContext mepCtx) {
                this.containedIterator = containedIterator;
                this.mepCtx = mepCtx;
            }
            
            // override remove() to make this Iterator class read-only
            public void remove() {
                throw new UnsupportedOperationException();
            }

            public boolean hasNext() {
                return containedIterator.hasNext();
            }

            public Object next() {
                // WARNING:  there's no real guarantee that the reason a migrator is iterating
                // over the properties is due to this being the source object for a putAll(source)
                // We would therefore be setting scope for a property that never actually makes
                // its way into the messageContext
                Entry entry = (Entry)containedIterator.next();
                mepCtx.setScope((String)entry.getKey(), Scope.APPLICATION);
                return entry;
            }
        }
     }
    
    /**
     * ApplicationPropertyMapWriter is similar to the ApplicationPropertyMapReader in that it
     * observes scope to determine what can be returned to a property migrator.  Individual
     * property migrators should only be allowed to retrieve APPLICATION-scoped properties.
     * 
     * TODO:  There's quite a bit of expensive logic that would need to go into this to be
     * fully correct.  For example, if a migrator calls size, we cannot simply return
     * userMap.size().  Rather, we would have to count only the APPLICATION scoped properties
     * and return those.
     * 
     * @author rott
     *
     */
    private static class ApplicationPropertyMapWriter extends HashMap<String, Object> {

        private Map<String, Object> userMap;
        private MEPContext mepCtx;
        
        public ApplicationPropertyMapWriter(Map<String, Object> userMap, MEPContext mepCtx) {
            this.userMap = userMap;
            this.mepCtx = mepCtx;
        }
        
        @Override
        public Object put(String key, Object value) {
            // notice the logic here!  We won't put a property on the userMap that is not APPLICATION scoped
            if (mepCtx.getScope(key) == Scope.APPLICATION) {
                return userMap.put(key, value);
            }
            return null;
        }

        @Override
        public void putAll(Map<? extends String, ? extends Object> m) {
            // we need to take advantage of the smarter put(String, Object)
            for (Iterator it = m.entrySet().iterator(); it.hasNext();) {
                Entry entry = (Entry)it.next();
                put((String)entry.getKey(), entry.getValue());
            }
        }
        
        @Override
        public boolean containsKey(Object key) {
            if (mepCtx.getScope((String)key) == Scope.APPLICATION) {
                return userMap.containsKey(key);
            }
            return false;
        }

        @Override
        public boolean containsValue(Object value) {
            return userMap.containsValue(value);
        }

        @Override
        public Set entrySet() {
            return userMap.entrySet();
        }

        @Override
        public Object get(Object key) {
            return userMap.get(key);
        }

        @Override
        public boolean isEmpty() {
            return userMap.isEmpty();
        }

        @Override
        public Set keySet() {
            return userMap.keySet();
        }

        @Override
        public Object remove(Object key) {
            return userMap.remove(key);
        }

        @Override
        public int size() {
            return userMap.size();
        }

        @Override
        public Collection values() {
            return userMap.values();
        }
     }
}