WeatherWizard JApplet : Applet « Development « Java Tutorial






/*
 * Copyright (c) 1995 - 2008 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:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions 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 nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Composite;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.net.URL;

import javax.imageio.ImageIO;
import javax.swing.JApplet;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.UIManager;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class WeatherWizard extends JApplet implements ChangeListener {

  WeatherPainter painter;

  public void init() {
    /* Turn off metal's use of bold fonts */
    UIManager.put("swing.boldMetal", Boolean.FALSE);
  }

  public void start() {
    initComponents();
  }

  public static void main(String[] args) {
    JFrame f = new JFrame("Weather Wizard");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JApplet ap = new WeatherWizard();
    ap.init();
    ap.start();
    f.add("Center", ap);
    f.pack();
    f.setVisible(true);

  }

  private BufferedImage loadImage(String name) {
    String imgFileName = "images/weather-" + name + ".png";
    URL url = WeatherWizard.class.getResource(imgFileName);
    BufferedImage img = null;
    try {
      img = ImageIO.read(url);
    } catch (Exception e) {
    }
    return img;
  }

  public void initComponents() {

    setLayout(new BorderLayout());

    JPanel p = new JPanel();
    p.add(new JLabel("Temperature:"));
    JSlider tempSlider = new JSlider(20, 100, 65);
    tempSlider.setMinorTickSpacing(5);
    tempSlider.setMajorTickSpacing(20);
    tempSlider.setPaintTicks(true);
    tempSlider.setPaintLabels(true);
    tempSlider.addChangeListener(this);
    p.add(tempSlider);
    add("North", p);

    painter = new WeatherPainter();
    painter.sun = loadImage("sun");
    painter.cloud = loadImage("cloud");
    painter.rain = loadImage("rain");
    painter.snow = loadImage("snow");
    painter.setTemperature(65);
    p.add("Center", painter);

  }

  public void stateChanged(ChangeEvent e) {
    JSlider slider = (JSlider) e.getSource();
    painter.setTemperature(slider.getValue());
  }
}

class WeatherPainter extends Component {

  int temperature = 65;

  String[] conditions = { "Snow", "Rain", "Cloud", "Sun" };

  BufferedImage snow = null;

  BufferedImage rain = null;

  BufferedImage cloud = null;

  BufferedImage sun = null;

  Color textColor = Color.yellow;

  String condStr = "";

  String feels = "";

  Composite alpha0 = null, alpha1 = null;

  BufferedImage img0 = null, img1 = null;

  void setTemperature(int temp) {
    temperature = temp;
    repaint();
  }

  public Dimension getPreferredSize() {
    return new Dimension(450, 125);
  }

  void setupText(String s1, String s2) {
    if (temperature <= 32) {
      textColor = Color.blue;
      feels = "Freezing";
    } else if (temperature <= 50) {
      textColor = Color.green;
      feels = "Cold";
    } else if (temperature <= 65) {
      textColor = Color.yellow;
      feels = "Cool";
    } else if (temperature <= 75) {
      textColor = Color.orange;
      feels = "Warm";
    } else {
      textColor = Color.red;
      feels = "Hot";
    }
    condStr = s1;
    if (s2 != null) {
      condStr += "/" + s2;
    }
  }

  void setupImages(BufferedImage i0) {
    alpha0 = null;
    alpha1 = null;
    img0 = i0;
    img1 = null;
  }

  void setupImages(int min, int max, BufferedImage i0, BufferedImage i1) {
    float alpha = (max - temperature) / (float) (max - min);
    alpha0 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha);
    alpha1 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1 - alpha);
    img0 = i0;
    img1 = i1;

  }

  void setupWeatherReport() {
    if (temperature <= 32) {
      setupImages(snow);
      setupText("Snow", null);
    } else if (temperature <= 40) {
      setupImages(32, 40, snow, rain);
      setupText("Snow", "Rain");
    } else if (temperature <= 50) {
      setupImages(rain);
      setupText("Rain", null);
    } else if (temperature <= 58) {
      setupImages(50, 58, rain, cloud);
      setupText("Rain", "Cloud");
    } else if (temperature <= 65) {
      setupImages(cloud);
      setupText("Cloud", null);
    } else if (temperature <= 75) {
      setupImages(65, 75, cloud, sun);
      setupText("Cloud", "Sun");
    } else {
      setupImages(sun);
      setupText("Sun", null);
    }
  }

  public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;
    Dimension size = getSize();
    Composite origComposite;

    setupWeatherReport();

    origComposite = g2.getComposite();
    if (alpha0 != null)
      g2.setComposite(alpha0);
    g2.drawImage(img0, 0, 0, size.width, size.height, 0, 0, img0.getWidth(null), img0
        .getHeight(null), null);
    if (img1 != null) {
      if (alpha1 != null)
        g2.setComposite(alpha1);
      g2.drawImage(img1, 0, 0, size.width, size.height, 0, 0, img1.getWidth(null), img1
          .getHeight(null), null);
    }
    g2.setComposite(origComposite);

    // Freezing, Cold, Cool, Warm, Hot,
    // Blue, Green, Yellow, Orange, Red
    Font font = new Font("Serif", Font.PLAIN, 36);
    g.setFont(font);

    String tempString = feels + " " + temperature + "F";
    FontRenderContext frc = ((Graphics2D) g).getFontRenderContext();
    Rectangle2D boundsTemp = font.getStringBounds(tempString, frc);
    Rectangle2D boundsCond = font.getStringBounds(condStr, frc);
    int wText = Math.max((int) boundsTemp.getWidth(), (int) boundsCond.getWidth());
    int hText = (int) boundsTemp.getHeight() + (int) boundsCond.getHeight();
    int rX = (size.width - wText) / 2;
    int rY = (size.height - hText) / 2;

    g.setColor(Color.LIGHT_GRAY);
    g2.fillRect(rX, rY, wText, hText);

    g.setColor(textColor);
    int xTextTemp = rX - (int) boundsTemp.getX();
    int yTextTemp = rY - (int) boundsTemp.getY();
    g.drawString(tempString, xTextTemp, yTextTemp);

    int xTextCond = rX - (int) boundsCond.getX();
    int yTextCond = rY - (int) boundsCond.getY() + (int) boundsTemp.getHeight();
    g.drawString(condStr, xTextCond, yTextCond);

  }
}








6.28.Applet
6.28.1.Applet
6.28.2.A real applet
6.28.3.Add JButton to JApplet
6.28.4.Access applet parameters
6.28.5.An Swing-based applet skeleton
6.28.6.Swing Applet
6.28.7.A simple Swing-based applet
6.28.8.Mini Appletviewer
6.28.9.Tic Tac Toe game
6.28.10.WeatherWizard JApplet
6.28.11.Change an applet background color
6.28.12.Read an applet parameters
6.28.13.Calling methods of an Applet from JavaScript code
6.28.14.Passing Parameters to Java Applet
6.28.15.Display message in browser status bar
6.28.16.System properties accessible to applets