org.psikeds.queryagent.interfaces.presenter.pojos.POJO.java Source code

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Here is the source code for org.psikeds.queryagent.interfaces.presenter.pojos.POJO.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
 * [ ] GNU Affero General Public License
 * [ ] GNU General Public License
 * [x] GNU Lesser General Public License
 * [ ] Creatice Commons ShareAlike License
 *
 * For details see file LICENSING in the top project directory
 *******************************************************************************/
package org.psikeds.queryagent.interfaces.presenter.pojos;

import java.io.Serializable;

import org.codehaus.jackson.annotate.JsonIgnore;
import org.codehaus.jackson.annotate.JsonTypeInfo;

import org.springframework.util.StringUtils;

import org.psikeds.common.util.JSONHelper;

/**
 * Base of all POJOs in this Package.
 * 
 * JSON-TypeInfo-Settings will be inherited by all derived Classes.
 * 
 * By default the ID of a POJO is for internal Usage only. If you want to make
 * it visible within JSON- or XML-Data, you have to expose it via public setters
 * and getters, e.g. see Variant-ID, Purpose-ID or Feature-ID.
 * 
 * @author marco@juliano.de
 * 
 */
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "@type")
public abstract class POJO implements Serializable, Comparable<Object> {

    private static final long serialVersionUID = 1L;

    public static final char COMPOSE_ID_SEPARATOR = '/';

    // unique id of this pojo
    private String id;

    protected POJO() {
        this.id = null;
    }

    protected POJO(final String id) {
        setId(id);
    }

    protected POJO(final String... ids) {
        setId(ids);
    }

    protected POJO(final POJO... pojos) {
        setId(pojos);
    }

    @JsonIgnore
    protected String getId() {
        return this.id;
    }

    @JsonIgnore
    protected void setId(final String id) {
        this.id = id;
    }

    @JsonIgnore
    protected void setId(final String... ids) {
        this.id = composeId(ids);
    }

    @JsonIgnore
    protected void setId(final POJO... pojos) {
        this.id = composeId(pojos);
    }

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

    /**
     * @return String Representation of this Object
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder(super.toString());
        sb.append('\n');
        sb.append(JSONHelper.dump(this));
        return sb.toString();
    }

    /**
     * @param obj
     *          a POJO
     * @return the value 0 if argument Object is a POJO of same Class and its ID is equal to
     *         the ID of this Object;
     *         a value greater than 0 if the specified Object is a POJO but has no ID
     *         or its ID is lexicographically less than the ID of this POJO;
     *         a value less 0 else
     * @see java.lang.Object#equals(Object obj)
     * @see java.lang.String#equals(String str)
     * @throws IllegalArgumentException
     *           if argument Object is null or not a POJO
     */
    @Override
    public int compareTo(final Object obj) {
        // check that obj is not null and a pojo
        if (!(obj instanceof POJO)) {
            throw new IllegalArgumentException("Not a POJO: " + String.valueOf(obj));
        }
        final POJO pojo = (POJO) obj;
        // check that this is the same type of pojo
        if (!pojo.getClass().equals(this.getClass())) {
            return pojo.getClass().getName().compareTo(this.getClass().getName());
        }
        // pojos without IDs can never be compared
        if (StringUtils.isEmpty(pojo.getId())) {
            return 1;
        }
        if (StringUtils.isEmpty(this.getId())) {
            return -1;
        }
        // compare IDs
        return this.getId().compareTo(pojo.getId());
    }

    /**
     * @return true if Object is not null, a POJO and has equal ID; false else
     * @see java.lang.Object#equals(Object obj)
     */
    @Override
    public boolean equals(final Object obj) {
        boolean ret;
        try {
            ret = (this.compareTo(obj) == 0);
        } catch (final Exception ex) {
            ret = false;
        }
        return ret;
    }

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

    public static String composeId(final POJO... pojos) {
        final StringBuilder sb = new StringBuilder();
        for (final POJO p : pojos) {
            final String pid = (p == null ? null : p.getId());
            if (!StringUtils.isEmpty(pid)) {
                if (sb.length() > 0) {
                    sb.append(COMPOSE_ID_SEPARATOR);
                }
                sb.append(pid);
            }
        }
        return sb.toString();
    }

    public static String composeId(final String... ids) {
        final StringBuilder sb = new StringBuilder();
        for (final String pid : ids) {
            if (!StringUtils.isEmpty(pid)) {
                if (sb.length() > 0) {
                    sb.append(COMPOSE_ID_SEPARATOR);
                }
                sb.append(pid);
            }
        }
        return sb.toString();
    }
}