de.iai.ilcd.model.common.XmlFile.java Source code

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Here is the source code for de.iai.ilcd.model.common.XmlFile.java

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/*******************************************************************************
 * Copyright (c) 2011 Karlsruhe Institute of Technology (KIT) - Institute for
 * Applied Computer Science (IAI).
 * 
 * This file is part of soda4LCA - the Service-Oriented Life Cycle Data Store.
 * 
 * soda4LCA is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * soda4LCA is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with soda4LCA. If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/

package de.iai.ilcd.model.common;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.Serializable;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

import javax.persistence.Basic;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.PostLoad;
import javax.persistence.PrePersist;
import javax.persistence.Table;
import javax.persistence.Transient;

import org.apache.commons.io.IOUtils;

/**
 * 
 * @author clemens.duepmeier
 */
@Entity
@Table(name = "xmlfile")
public class XmlFile implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    /**
     * Uncompressed version of XML content. Is not stored in database, will be set automatically after loading
     * {@link #compressedContent} from database.
     * 
     * @see #decompressContent()
     */
    @Transient
    protected String content;

    /**
     * Compressed version of {@link #content}. Is being auto generated prior to persist/merge
     * 
     * @see #compressContent()
     */
    @Basic
    private byte[] compressedContent;

    public Long getId() {
        return this.id;
    }

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

    public String getContent() {
        return this.content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (this.id != null ? this.id.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof XmlFile)) {
            return false;
        }
        XmlFile other = (XmlFile) object;
        if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    /**
     * Compress the content of XML file prior to persist/merge events in order to save database space and be compatible
     * with MySQL server default configurations
     * as long as possible (1MB max package size)
     * 
     * @throws Exception
     *             if anything goes wrong, just in-memory IO operations, should not happen
     * @see #decompressContent()
     */
    @PrePersist
    protected void compressContent() throws Exception {
        if (this.content == null) {
            this.compressedContent = null;
        } else {
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            GZIPOutputStream gzipOut = new GZIPOutputStream(out);
            gzipOut.write(this.content.getBytes("UTF-8"));
            gzipOut.flush();
            gzipOut.close();
            this.compressedContent = out.toByteArray();
        }
    }

    /**
     * Decompress content of XML file after loading. The reason for doing this, see {@link #compressContent()}
     * 
     * @throws Exception
     *             if anything goes wrong, just in-memory IO operations, should not happen
     * @see #compressContent()
     */
    @PostLoad
    protected void decompressContent() throws Exception {
        if (this.compressedContent == null || this.compressedContent.length == 0) {
            this.content = null;
        } else {
            GZIPInputStream gzipIn = new GZIPInputStream(new ByteArrayInputStream(this.compressedContent));
            this.content = new String(IOUtils.toByteArray(gzipIn), "UTF-8");
        }
    }

    @Override
    public String toString() {
        return "de.iai.ilcd.model.common.XmlFile[id=" + this.id + "]";
    }

    public byte[] getContentHash() {
        MessageDigest md;
        try {
            md = MessageDigest.getInstance("MD5");
            return md.digest(this.compressedContent);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return new byte[0];
    }
}