一个图片查看器能够打开选择器面板

import java.awt.Graphics;
import java.awt.MouseInfo;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.io.File;


import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.filechooser.FileNameExtensionFilter;


public class App extends JFrame implements MouseListener, ActionListener {


int x = 0;
int y = 0;
File[] selectedFiles = null;
int fileIndex = 0;
int width = 200;
int height = 200;


public App() {


setDefaultCloseOperation(EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setSize(400, 300);
setResizable(false);
getContentPane().setLayout(null);


JPanel panel = new ImagePanel();
panel.setBounds(12, 40, 370, 218);
getContentPane().add(panel);


addMouseListener(this);
JButton btnBrowse = new JButton("Browse");
btnBrowse.addActionListener(this);
btnBrowse.setBounds(12, 9, 91, 21);
getContentPane().add(btnBrowse);
setVisible(true);
}


public static void main(String[] args) {
new App();
}


public void actionPerformed(ActionEvent e) {
JFileChooser chooser = new JFileChooser();
chooser.setMultiSelectionEnabled(true);
FileNameExtensionFilter filter = new FileNameExtensionFilter(
"JPG & GIF Images", "jpg", "gif");
// 设置文件类型
chooser.setFileFilter(filter);
// 打开选择器面板
int returnVal = chooser.showOpenDialog(this);
if (returnVal == JFileChooser.APPROVE_OPTION) {
selectedFiles = chooser.getSelectedFiles();
repaint();
}
}


public void mouseClicked(MouseEvent e) {


}


public void mouseEntered(MouseEvent e) {


}


public void mouseExited(MouseEvent e) {


}


public void mousePressed(MouseEvent e) {
Point point = MouseInfo.getPointerInfo().getLocation();
x = point.x;
y = point.y;
}


public void mouseReleased(MouseEvent e) {
Point point = MouseInfo.getPointerInfo().getLocation();
int thisX = point.x;
int thisY = point.y;
System.out.println("thisX=" + thisX + "  " + "thisY=" + thisY);
if ((y - thisY < 20 && y - thisY > 0)
|| (y - thisY < 0 && y - thisY > -20)) {
// Y 在20范围内移动认为是水平移动
if (x < thisX) {
// right
if (selectedFiles != null
&& fileIndex < selectedFiles.length - 1) {
fileIndex++;
}
} else {
// left
if (selectedFiles != null && fileIndex > 0) {
fileIndex--;
}
}
} else {
if (x < thisX) {
// 右下
width += 20;
height += 20;
} else {
// 左上
width -= 20;
height -= 20;
}
}


repaint();
}


class ImagePanel extends JPanel {


public void paint(Graphics g) {
super.paint(g);


if (selectedFiles != null) {
ImageIcon icon = new ImageIcon(selectedFiles[fileIndex]
.getPath());
g.drawImage(icon.getImage(), 0, 0, width, height, this);
}
}
}
}