org.springframework.batch.core.Entity.java Source code

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Here is the source code for org.springframework.batch.core.Entity.java

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/*
 * Copyright 2006-2013 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.batch.core;

import java.io.Serializable;

import org.springframework.util.ClassUtils;

/**
 * Batch Domain Entity class. Any class that should be uniquely identifiable
 * from another should subclass from Entity. More information on this pattern
 * and the difference between Entities and Value Objects can be found in Domain
 * Driven Design by Eric Evans.
 *
 * @author Lucas Ward
 * @author Dave Syer
 *
 */
@SuppressWarnings("serial")
public class Entity implements Serializable {

    private Long id;

    private volatile Integer version;

    public Entity() {
        super();
    }

    public Entity(Long id) {
        super();

        //Commented out because StepExecutions are still created in a disconnected
        //manner.  The Repository should create them, then this can be uncommented.
        //Assert.notNull(id, "Entity id must not be null.");
        this.id = id;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    /**
     * @return the version
     */
    public Integer getVersion() {
        return version;
    }

    /**
     * Public setter for the version needed only by repository methods.
     * @param version the version to set
     */
    public void setVersion(Integer version) {
        this.version = version;
    }

    /**
     * Increment the version number
     */
    public void incrementVersion() {
        if (version == null) {
            version = 0;
        } else {
            version = version + 1;
        }
    }

    @Override
    public String toString() {
        return String.format("%s: id=%d, version=%d", ClassUtils.getShortName(getClass()), id, version);
    }

    /**
     * Attempt to establish identity based on id if both exist. If either id
     * does not exist use Object.equals().
     *
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals(Object other) {
        if (other == this) {
            return true;
        }
        if (other == null) {
            return false;
        }
        if (!(other instanceof Entity)) {
            return false;
        }
        Entity entity = (Entity) other;
        if (id == null || entity.getId() == null) {
            return false;
        }
        return id.equals(entity.getId());
    }

    /**
     * Use ID if it exists to establish hash code, otherwise fall back to
     * Object.hashCode(). Based on the same information as equals, so if that
     * changes, this will. N.B. this follows the contract of Object.hashCode(),
     * but will cause problems for anyone adding an unsaved {@link Entity} to a
     * Set because Set.contains() will almost certainly return false for the
     * {@link Entity} after it is saved. Spring Batch does not store any of its
     * entities in Sets as a matter of course, so internally this is consistent.
     * Clients should not be exposed to unsaved entities.
     *
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        if (id == null) {
            return super.hashCode();
        }
        return 39 + 87 * id.hashCode();
    }

}