com.adaptris.util.PseudoRandomIdGenerator.java Source code

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Here is the source code for com.adaptris.util.PseudoRandomIdGenerator.java

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/*
 * Copyright 2015 Adaptris Ltd.
 * 
 * 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.adaptris.util;

import static org.apache.commons.lang.StringUtils.isEmpty;

import java.security.SecureRandom;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;

import org.apache.commons.lang3.BooleanUtils;

import com.adaptris.annotation.AdvancedConfig;
import com.adaptris.annotation.InputFieldDefault;
import com.adaptris.util.text.Conversion;
import com.thoughtworks.xstream.annotations.XStreamAlias;

/**
 * Pseudo Random {@linkplain IdGenerator} implementation
 * <p>
 * The ID is generated from the a combination of {@linkplain Random#nextBytes(byte[])} (8 bytes, and then base64 encoded),
 * along with the configured prefix to generate an id. No guarantees are made for the uniqueness of the id that is generated. If you
 * wish for a unique-id then you should consider using {@link GuidGenerator} instead.
 * </p>
 * <p>
 * Effectively the ID that is generated follows the form
 * 
 * <pre>
 * {@code 
ID              = prefix unique-sequence
prefix          = *VCHAR
unique sequence = 12(ALPHA/DIGIT/"+"/"/"/"=")
}
   </pre>
 * 
 * </p>
 * <p>
 * If you wish to restrict the length of the resulting ID, then bear in mind that with padding 8 bytes base64 encoded is 12
 * characters long so consider how long your prefix is.
 * </p>
 * 
 * @config pseudo-random-id-generator
 * 
 * @author lchan
 * @author $Author: lchan $
 */
@XStreamAlias("pseudo-random-id-generator")
public class PseudoRandomIdGenerator implements IdGenerator {

    @InputFieldDefault(value = "")
    private String prefix;
    @AdvancedConfig
    @InputFieldDefault(value = "true")
    private Boolean useSecureRandom;
    private final static SecureRandom SECURE_RAND = new SecureRandom();

    public PseudoRandomIdGenerator() {
        setPrefix("");
    }

    public PseudoRandomIdGenerator(String prefix) {
        this();
        setPrefix(prefix);
    }

    public PseudoRandomIdGenerator(String prefix, boolean useSecureRandom) {
        this();
        setPrefix(prefix);
        setUseSecureRandom(useSecureRandom);
    }

    /**
     * A generated ID.
     *
     *
     *
     */
    public String create(Object msg) {
        byte[] bytes = new byte[8];
        random().nextBytes(bytes);
        return getPrefix() + Conversion.byteArrayToBase64String(bytes);
    }

    /**
     * @return the separator
     */
    public String getPrefix() {
        return prefix;
    }

    /**
     * @param s the separator to set
     */
    public void setPrefix(String s) {
        if (isEmpty(s)) {
            prefix = "";
        } else {
            prefix = s;
        }
    }

    /**
     * @return the useSecureRandom
     */
    public Boolean getUseSecureRandom() {
        return useSecureRandom;
    }

    /**
     * Whether or not to use {@link SecureRandom} when generating a random sequence of bytes.
     * 
     * @param u the useSecureRandom to set, if not set, defaults to true.
     */
    public void setUseSecureRandom(Boolean u) {
        this.useSecureRandom = u;
    }

    boolean useSecureRandom() {
        return BooleanUtils.toBooleanDefaultIfNull(getUseSecureRandom(), true);
    }

    Random random() {
        return useSecureRandom() ? SECURE_RAND : ThreadLocalRandom.current();
    }
}