import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
public class DownloadingImages {
ImageDisplay displayPanel;
String[] paths = {
"http://antwrp.gsfc.nasa.gov/apod/image/0712/m74_hst_800c.jpg",
"http://antwrp.gsfc.nasa.gov/apod/image/0711/pleiades_fs.jpg",
"http://antwrp.gsfc.nasa.gov/apod/image/0711/crescent_bugnet.jpg",
"http://antwrp.gsfc.nasa.gov/apod/image/0712/" +
"HindsVariable_goldman800.jpg"
};
private class EventHandler implements ActionListener {
BufferedImage image;
int count = 0;
public void actionPerformed(ActionEvent evt) {
String ac = evt.getActionCommand();
// images are download before display
if (ac.equals("load image")) {
count++;
if (count == paths.length)
count=0;
long start = System.currentTimeMillis();
image = downloadImage(paths[count]);
String name = getName(paths[count]);
long end = System.currentTimeMillis();
double time = (end - start)/1000.0;
System.out.printf("load time for %s was: %.1f seconds%n",
name, time);
}
if (ac.equals("show image")) {
int imgwidth = 0, imgheight = 0;
try {
imgwidth = image.getWidth();
} catch (Exception e) {
System.out.println("can not get image width " + imgwidth);
System.out.println(e.getMessage());
}
try {
imgheight = image.getHeight();
} catch (Exception e) {
System.out.println("can not get image height " + imgheight);
System.out.println(e.getMessage());
}
displayPanel.setImage(image);
}
if(ac.equals("load all"))
loadAllImages();
}
private String getName(String s) {
int lastSlash = s.lastIndexOf("/");
if(lastSlash > -1 && lastSlash < s.length()-1)
return s.substring(lastSlash+1);
return null;
}
}
private BufferedImage downloadImage(String path) {
BufferedImage image = null;
try {
URL url = new URL(path);
image = ImageIO.read(url);
} catch (IOException ex) {
System.out.println("can not read : " + path);
System.out.println(ex.getMessage());
}
return image;
}
private class ImageDisplay extends JPanel {
BufferedImage image;
public ImageDisplay() {
// this belongs here
this.setBackground(Color.WHITE);
}
protected void paintComponent(Graphics g) {
// This next line will fill component background
// with background color specified in constructor
// above.
super.paintComponent(g);
if(image != null) {
int x = (getWidth() - image.getWidth())/2;
int y = (getHeight() - image.getHeight())/2;
g.drawImage(image, x, y, this);
}
}
public void setImage(BufferedImage image) {
this.image = image;
Dimension d = new Dimension(image.getWidth(),
image.getHeight());
setPreferredSize(d);
revalidate();
repaint();
}
}
private void loadAllImages() {
Thread thread = new Thread(new Runnable() {
public void run() {
long start = System.currentTimeMillis();
BufferedImage[] images =
new BufferedImage[paths.length];
for(int i = 0; i < images.length; i++) {
try {
URL url = new URL(paths[i]);
images[i] = ImageIO.read(url);
} catch(IOException e) {
System.out.println("read error for: " +
paths[i] + ": " +
e.getMessage());
}
}
long end = System.currentTimeMillis();
double time = (end - start)/1000.0;
String s = "Images loaded in " + time + " seconds";
JOptionPane.showMessageDialog(null, s,
"images loaded", -1);
/*
JPanel panel = new JPanel(new GridLayout(2,0));
JScrollPane scrollPane = new JScrollPane(panel);
scrollPane.setPreferredSize(new Dimension(500,500));
for(int i = 0; i < images.length; i++) {
panel.add(new JLabel(new ImageIcon(images[i])));
}
JOptionPane.showMessageDialog(null, scrollPane,
"images", -1);
*/
}
});
thread.setPriority(Thread.NORM_PRIORITY);
thread.start();
}
private JScrollPane getImagePanel() {
displayPanel = new ImageDisplay();
return new JScrollPane(displayPanel);
}
private JPanel getButtonPanel() {
String[] ids = { "load image", "show image", "load all" };
EventHandler handler = new EventHandler();
JPanel panel = new JPanel();
for(int j = 0; j < ids.length; j++) {
JButton button = new JButton(ids[j]);
button.setActionCommand(ids[j]);
button.addActionListener(handler);
panel.add(button);
}
return panel;
}
public static void main(String[] args) {
DownloadingImages test = new DownloadingImages();
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(test.getImagePanel());
f.add(test.getButtonPanel(), "Last");
f.setSize(400,400);
f.setLocation(200,200);
f.setVisible(true);
}
}
Linear Mode
