com.cloudera.nav.plugin.client.writer.registry.AbstractRegistryFactory.java Source code

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Here is the source code for com.cloudera.nav.plugin.client.writer.registry.AbstractRegistryFactory.java

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/*
 * Copyright (c) 2015 Cloudera, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.cloudera.nav.plugin.client.writer.registry;

import com.google.common.base.Preconditions;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.Lists;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.Collection;

public abstract class AbstractRegistryFactory<T> {

    private static final int MAX_CACHE_SIZE = 100;

    public LoadingCache<Class<?>, Collection<T>> newRegistry() {
        return CacheBuilder.newBuilder().maximumSize(MAX_CACHE_SIZE)
                .build(new CacheLoader<Class<?>, Collection<T>>() {
                    @Override
                    public Collection<T> load(Class<?> aClass) throws Exception {
                        return parseMClass(aClass);
                    }
                });
    }

    private Collection<T> parseMClass(Class<?> aClass) {
        Collection<T> properties = Lists.newArrayList();
        for (Method method : aClass.getMethods()) {
            if (isValidMethod(method)) {
                properties.add(createEntry(method));
            }
        }
        return properties;
    }

    private boolean isValidMethod(Method method) {
        if (method.isAnnotationPresent(getTypeClass()) && !method.isBridge()) {
            // TODO can we validate earlier?
            Preconditions.checkArgument(method.getParameterTypes().length == 0,
                    "MProperty should only be used on getter methods");
            return true;
        }
        return false;
    }

    protected abstract Class<? extends Annotation> getTypeClass();

    protected abstract T createEntry(Method method);
}