Quadcap Image Database

com/quadcap/app/dbimage/DbImageServlet.java

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package com.quadcap.app.dbimage;

/* Copyright 2000 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import java.util.Enumeration;
import java.util.Properties;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.SQLException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

// ---- image libraries
import java.awt.Image;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.io.FileOutputStream;
import javax.swing.ImageIcon;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

/**
 * This servlet fetches and returns images from the database.
 *
 * @author Stan Bailes
 */
public class DbImageServlet extends HttpServlet {
    String                              url     = null;
    
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        try {
            url = config.getInitParameter("jdbc.url");
            if (url == null) {
                throw new ServletException("No jdbc.url property");
            } else {
                String driver = "com.quadcap.jdbc.JdbcDriver";
                String d = config.getInitParameter("jdbc.driver");
                if (d != null) driver = d;
                Class.forName(driver);
            }
            config.getServletContext().setAttribute("servlet", this);

            Connection conn = getConnection();
            Statement stmt = conn.createStatement();
            try {
                DatabaseMetaData dbmeta = conn.getMetaData();
                ResultSet rs = dbmeta.getTables(null, null, "images", null);
                if (!rs.next()) {
                    stmt.execute(
                        "create table images(" +
                        " name varchar(99999), " +
                        " maxDim int, " +
                        " data blob," +
                        " size int)");
                    stmt.execute(
                        "create unique index images1 on images(name, maxDim)");
                }
                rs.close();
            } finally {
                stmt.close();
                conn.close();
            } 

        } catch (Exception e) {
            e.printStackTrace(System.err);
            throw new ServletException(e);
        }
    }

    public Connection getConnection() throws SQLException {
        Properties p = new Properties();
        p.put("create", "true");
        return DriverManager.getConnection(url, p);
    }
    
    byte[] resizeImage(byte[] imageBytes, int maxDim) throws IOException {
        ImageIcon inImage = new ImageIcon(imageBytes);
        
        // Determine the scale.
        double scale = (double)maxDim/(double)inImage.getIconHeight();

        if (inImage.getIconWidth() > inImage.getIconHeight()) {
            scale = (double)maxDim/(double)inImage.getIconWidth();
        }

        // Determine size of new image. 
        // One of them hould equal maxDim.
        int scaledW = (int)(scale*inImage.getIconWidth());
        int scaledH = (int)(scale*inImage.getIconHeight());

        // Create an image buffer in which to paint on.
        BufferedImage outImage = new BufferedImage(scaledW, scaledH,
                                                   BufferedImage.TYPE_INT_RGB);
            
        // Set the scale.
        AffineTransform tx = new AffineTransform();

        // If the image is smaller than the desired image size,
        // don't bother scaling.
        if (scale < 1.0d) {
            tx.scale(scale, scale);
        }

        // Paint image.
        Graphics2D g2d = outImage.createGraphics();
        g2d.drawImage(inImage.getImage(), tx, null);
        g2d.dispose();

        // JPEG-encode the image and write the response
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        JPEGImageEncoder encoder = 
            JPEGCodec.createJPEGEncoder(os);
        encoder.encode(outImage);

        return os.toByteArray();
    }

    void sendImage(byte[] image, HttpServletResponse response)
        throws ServletException, IOException
    {
        OutputStream os = response.getOutputStream();
        response.setContentLength(image.length);
        os.write(image);
    }

    void storeImage(Connection conn, byte[] image, String name, int dim)
        throws SQLException
    {
        PreparedStatement p = conn.prepareStatement(
            "insert into images(?,?,?,?)");
        p.clearParameters();
        p.setString(1, name);
        p.setInt(2, image.length);
        p.setBytes(3, image);
        p.setInt(4, dim);
        p.executeUpdate();
        p.close();
    }

    public void doGet(HttpServletRequest request,
                      HttpServletResponse response)
        throws ServletException
    {
        String s = request.getServletPath();
        response.setContentType(getServletContext().getMimeType(s));
        Connection conn;
        try {
            conn = getConnection();
        } catch (SQLException ex) {
            throw new ServletException(ex);
        }
        int dim = -1;
        String mdim = request.getParameter("maxDim");
        if (mdim != null) {
            dim = Integer.parseInt(mdim);
        }
        try {
            Statement stmt = conn.createStatement();
            if (dim <= 0) {
                ResultSet rs = stmt.executeQuery(
                    "select data from images where name = '" + s +
                    "' and maxDim <= 0");
                if (rs.next()) {
                    byte[] image = rs.getBytes(1);
                    rs.close();
                    sendImage(image, response);
                } else {
                    rs.close();
                    // not found
                }
            } else {
                ResultSet rs = stmt.executeQuery(
                    "select data from images where name ='" + s +
                    "' and maxDim = " + dim);
                if (rs.next()) {
                    byte[] image = rs.getBytes(1);
                    rs.close();
                    sendImage(image, response);
                } else {
                    rs.close();
                    rs = stmt.executeQuery(
                        "select data, size from images where name = '" + s +
                        "' and maxDim <= 0");
                    if (rs.next()) {
                        byte[] image = rs.getBytes(1);
                        rs.close();
                        byte[] resized = resizeImage(image, dim);
                        storeImage(conn, resized, s, dim);
                        sendImage(resized, response);
                    } else {
                        // not found
                        rs.close();
                    }
                }
            }
        } catch (Throwable t) {
            throw new ServletException(t);
        } finally {
            try {
                conn.close();
            } catch (Throwable t) {
                throw new ServletException(t);
            }
        }
    }

}