com.cask.twitter.MapSerdesUtil.java Source code

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Here is the source code for com.cask.twitter.MapSerdesUtil.java

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/*
 * Copyright  2014 Cask Data, 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.cask.twitter;

import com.google.common.collect.Maps;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

/**
 * Utility Class for (De)Serializing Map and for sorting Map based on value (score).
 */
public final class MapSerdesUtil {
    private static final Logger LOG = LoggerFactory.getLogger(MapSerdesUtil.class);

    public static byte[] serializeMap(Map<String, Double> map) {
        ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
        try {
            ObjectOutputStream out = new ObjectOutputStream(byteOut);
            out.writeObject(map);
        } catch (Throwable t) {
            LOG.error(t.getMessage(), t);
        }
        return byteOut.toByteArray();
    }

    @SuppressWarnings("unchecked")
    public static Map<String, Double> deserializeMap(byte[] bytes) {
        if (bytes == null) {
            return Maps.newHashMap();
        }

        try {
            ByteArrayInputStream byteIn = new ByteArrayInputStream(bytes);
            ObjectInputStream in = new ObjectInputStream(byteIn);
            return (Map<String, Double>) in.readObject();
        } catch (Throwable t) {
            LOG.error(t.getMessage(), t);
            return Maps.newHashMap();
        }
    }

    @SuppressWarnings("unchecked")
    public static Map sortByComparator(Map unsortMap) {
        List list = new LinkedList(unsortMap.entrySet());
        //Sort list based on comparator
        Collections.sort(list, new Comparator() {
            public int compare(Object o1, Object o2) {
                return ((Comparable) ((Map.Entry) (o2)).getValue()).compareTo(((Map.Entry) (o1)).getValue());
            }
        });

        //Put sorted list into map again
        //LinkedHashMap retains the order in which keys were inserted
        Map sortedMap = new LinkedHashMap();
        Iterator it = list.iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry) it.next();
            sortedMap.put(entry.getKey(), entry.getValue());
        }
        return sortedMap;
    }

    private MapSerdesUtil() {
    }
}