org.psikeds.common.idgen.impl.RequestIdGenerator.java Source code

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Here is the source code for org.psikeds.common.idgen.impl.RequestIdGenerator.java

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/*******************************************************************************
 * psiKeds :- ps induced knowledge entity delivery system
 *
 * Copyright (c) 2013, 2014 Karsten Reincke, Marco Juliano, Deutsche Telekom AG
 *
 * This file is free software: you can redistribute
 * it and/or modify it under the terms of the
 * [x] GNU Affero General Public License
 * [ ] GNU General Public License
 * [ ] GNU Lesser General Public License
 * [ ] Creatice Commons ShareAlike License
 *
 * For details see file LICENSING in the top project directory
 *******************************************************************************/
package org.psikeds.common.idgen.impl;

import java.net.InetAddress;
import java.security.NoSuchAlgorithmException;

import org.apache.commons.lang.StringUtils;

import org.psikeds.common.idgen.IdGenerator;

/**
 * Generates a (most probably) unique Request-ID like this:
 * 
 * <hostname>-<random ascii characters>-<current time in ms>
 * 
 * @author marco@juliano.de
 */
public class RequestIdGenerator extends RandomStringGenerator implements IdGenerator {

    public static final boolean DEFAULT_INCLUDE_HOSTNAME = false;
    public static final boolean DEFAULT_RESOLVE_HOSTNAME = false;
    public static final boolean DEFAULT_INCLUDE_TIMESTAMP = true;

    private boolean includeHostname;
    private boolean resolveHostname;
    private boolean includeTimestamp;
    private String hostName;

    public RequestIdGenerator() throws NoSuchAlgorithmException {
        this(DEFAULT_INCLUDE_TIMESTAMP, DEFAULT_INCLUDE_HOSTNAME, DEFAULT_RESOLVE_HOSTNAME);
    }

    public RequestIdGenerator(final boolean its, final boolean ihn, final boolean rhn)
            throws NoSuchAlgorithmException {
        super();
        this.includeTimestamp = its;
        this.includeHostname = ihn;
        this.resolveHostname = rhn;
        initHostName();
    }

    public void initHostName() {
        try {
            if (this.includeHostname && StringUtils.isEmpty(this.hostName)) {
                final InetAddress localMachine = InetAddress.getLocalHost();
                // InetAddress.getHostName() performs a Nameservice-Lookup.
                // This can be a very expensive Operation, worst case blocking
                // for several Minutes until some Timeout occurs!
                this.hostName = (this.resolveHostname ? localMachine.getHostName() : localMachine.getHostAddress());
            }
        } catch (final Exception ex) {
            this.hostName = null;
            this.includeHostname = false;
            this.resolveHostname = false;
        }
    }

    // ------------------------------------------------------

    public String getHostName() {
        return this.hostName;
    }

    public void setHostName(final String hostName) {
        this.hostName = hostName;
    }

    public boolean isResolveHostname() {
        return this.resolveHostname;
    }

    public void setResolveHostname(final boolean resolveHostname) {
        this.resolveHostname = resolveHostname;
    }

    public boolean isIncludeHostname() {
        return this.includeHostname;
    }

    public void setIncludeHostname(final boolean includeHostname) {
        this.includeHostname = includeHostname;
    }

    public boolean isIncludeTimestamp() {
        return this.includeTimestamp;
    }

    public void setIncludeTimestamp(final boolean includeTimestamp) {
        this.includeTimestamp = includeTimestamp;
    }

    // ------------------------------------------------------

    /**
     * @return String next request id
     * @see org.psikeds.common.idgen.IdGenerator#getNextId()
     */
    @Override
    public String getNextId() {
        final StringBuilder sb = new StringBuilder();
        if (this.includeHostname && !StringUtils.isEmpty(this.hostName)) {
            sb.append(this.hostName);
            sb.append('-');
        }
        sb.append(super.getNextId());
        if (this.includeTimestamp) {
            sb.append('-');
            sb.append(System.currentTimeMillis());
        }
        return sb.toString();
    }
}