com.cloudera.nav.plugin.model.MD5IdGenerator.java Source code

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Here is the source code for com.cloudera.nav.plugin.model.MD5IdGenerator.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.model;

import com.cloudera.nav.plugin.model.entities.Entity;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.hash.Hasher;
import com.google.common.hash.Hashing;

import java.util.regex.Pattern;

import org.apache.commons.lang.StringUtils;

/**
 * Factory class for generating unique identities for one or more strings
 */
public class MD5IdGenerator {

    @VisibleForTesting
    public static Pattern MD5_PATTERN = Pattern.compile("[a-fA-F0-9]{32}");

    /**
     * Generates identity by creating MD5 hash on combination of all the specified
     * arg in order.
     */
    public static String generateIdentity(String... args) {
        MD5IdGenerator h = new MD5IdGenerator();
        h.update(args);
        return h.getIdentity();
    }

    public static boolean isValidId(String id) {
        return !StringUtils.isEmpty(id) && MD5_PATTERN.matcher(id).matches();
    }

    private final Hasher hasher = Hashing.md5().newHasher();

    /**
     * Update the MD5 Hasher with given string followed by the entity separator
     * @param arg
     */
    public void update(String arg) {
        hasher.putString(arg);
        hasher.putString(Entity.ID_SEPARATOR);
    }

    /**
     * Update the MD5 Hasher with given strings followed by the entity separator
     * @param args
     */
    public void update(String... args) {
        int i = 0;
        for (String arg : args) {
            if (arg != null) {
                hasher.putString(arg);
            }
            if (i < args.length - 1) {
                hasher.putString(Entity.ID_SEPARATOR);
            }
            i++;
        }
    }

    public String getIdentity() {
        return hasher.hash().toString();
    }

}