OutputApplet.java Source code

Introduction

Here is the source code for OutputApplet.java

Source

/* From http://java.sun.com/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
/**
 * This is a demonstration JDBC applet. It displays some simple standard output
 * from the Coffee database.
 */

import java.applet.Applet;
import java.awt.Graphics;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Vector;

public class OutputApplet extends Applet implements Runnable {
    private Thread worker;

    private Vector queryResults;

    private String message = "Initializing";

    public synchronized void start() {
        // Every time "start" is called we create a worker thread to
        // re-evaluate the database query.
        if (worker == null) {
            message = "Connecting to database";
            worker = new Thread(this);
            worker.start();
        }
    }

    /**
     * The "run" method is called from the worker thread. Notice that because
     * this method is doing potentially slow databases accesses we avoid making
     * it a synchronized method.
     */

    public void run() {
        String url = "jdbc:mySubprotocol:myDataSource";
        String query = "select COF_NAME, PRICE from COFFEES";

        try {
            Class.forName("myDriver.ClassName");
        } catch (Exception ex) {
            setError("Can't find Database driver class: " + ex);
            return;
        }

        try {
            Vector results = new Vector();
            Connection con = DriverManager.getConnection(url, "myLogin", "myPassword");
            Statement stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery(query);
            while (rs.next()) {
                String s = rs.getString("COF_NAME");
                float f = rs.getFloat("PRICE");
                String text = s + "     " + f;
                results.addElement(text);
            }

            stmt.close();
            con.close();

            setResults(results);

        } catch (SQLException ex) {
            setError("SQLException: " + ex);
        }
    }

    /**
     * The "paint" method is called by AWT when it wants us to display our
     * current state on the screen.
     */

    public synchronized void paint(Graphics g) {
        // If there are no results available, display the current message.
        if (queryResults == null) {
            g.drawString(message, 5, 50);
            return;
        }

        // Display the results.
        g.drawString("Prices of coffee per pound:  ", 5, 10);
        int y = 30;
        java.util.Enumeration e = queryResults.elements();
        while (e.hasMoreElements()) {
            String text = (String) e.nextElement();
            g.drawString(text, 5, y);
            y = y + 15;
        }
    }

    /**
     * This private method is used to record an error message for later display.
     */

    private synchronized void setError(String mess) {
        queryResults = null;
        message = mess;
        worker = null;
        // And ask AWT to repaint this applet.
        repaint();
    }

    /**
     * This private method is used to record the results of a query, for later
     * display.
     */

    private synchronized void setResults(Vector results) {
        queryResults = results;
        worker = null;
        // And ask AWT to repaint this applet.
        repaint();
    }
}