org.psikeds.resolutionengine.datalayer.vo.ValueObject.java Source code

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Here is the source code for org.psikeds.resolutionengine.datalayer.vo.ValueObject.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.resolutionengine.datalayer.vo;

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 Value-Objects in this Package.
 * 
 * JSON-TypeInfo-Settings will be inherited by all derived Classes.
 * 
 * By default the ID of a ValueObject 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. For Examples see Rule, Event, Purpose, etc.
 * 
 * @author marco@juliano.de
 * 
 */
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "@type")
public abstract class ValueObject implements Serializable, Comparable<Object> {

    private static final long serialVersionUID = 1L;
    private static final char COMPOSE_ID_SEPARATOR = '/';

    // unique id of this Value Object
    protected String id;

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

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

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

    protected ValueObject(final ValueObject... vos) {
        setId(vos);
    }

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

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

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

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

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

    /**
     * @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 ValueObject
     * @return the value 0 if argument Object is a ValueObject 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 ValueObject but has no ID
     *         or its ID is lexicographically less than the ID of this Object;
     *         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 ValueObject
     */
    @Override
    public int compareTo(final Object obj) {
        // check that obj is not null and a value object
        if (!(obj instanceof ValueObject)) {
            throw new IllegalArgumentException("Not a ValueObject: " + String.valueOf(obj));
        }
        final ValueObject vo = (ValueObject) obj;
        // check that this is the same type of value object
        if (!vo.getClass().equals(this.getClass())) {
            return vo.getClass().getName().compareTo(this.getClass().getName());
        }
        // value objects without IDs can never be compared
        if (StringUtils.isEmpty(vo.getId())) {
            return 1;
        }
        if (StringUtils.isEmpty(this.getId())) {
            return -1;
        }
        // compare IDs
        return this.getId().compareTo(vo.getId());
    }

    /**
     * @return true if Object is not null, a ValueObject 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;
    }

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

    protected static String composeId(final ValueObject... vos) {
        final StringBuilder sb = new StringBuilder();
        if (vos != null) {
            for (final ValueObject v : vos) {
                final String vid = (v == null ? null : v.getId());
                if (!StringUtils.isEmpty(vid)) {
                    if (sb.length() > 0) {
                        sb.append(COMPOSE_ID_SEPARATOR);
                    }
                    sb.append(vid.trim());
                }
            }
        }
        return sb.toString();
    }

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