今天在学习的过程中,看到一段把JFileChooser作为组件添加到JFrame中的程序,但是却无法对JFileChooser中的open和cancel按钮进行操作。于是自己写了一个JFileChooser来实现支持图片预览的图片选择对话框,并且支持以默认的打开方式打开选择的图片。
下面是MyFileChooser的代码:
import java.awt.Dimension;
import java.awt.Image;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.net.MalformedURLException;
import javax.swing.JFileChooser;
import javax.swing.border.BevelBorder;
public class MyFileChooser extends JFileChooser {
/**
*
*/
private static final long serialVersionUID = 1L;
private PaintPanel paint;
public MyFileChooser() {
super();
//新建PaintPanel用来显示图片预览
paint = new PaintPanel();
//给PaintPanel绘制边框
paint.setBorder(new BevelBorder(BevelBorder.LOWERED,null,null,null,null));
//给PaintPanel设置大小4:3
paint.setPreferredSize(new Dimension(400, 300));
//设置辅助控件
this.setAccessory(paint);
//新建监听器
this.addPropertyChangeListener(new PropertyChangeListener() {
public void propertyChange(PropertyChangeEvent arg0) {
//一旦选择的文件发生了变化,调用相应的方法
do_this_propertyChange(arg0);
}
});
}
protected void do_this_propertyChange(PropertyChangeEvent e) {
// TODO Auto-generated method stub
// System.out.println("changed");
// JFileChooser的被选文件已经发生了改变
if (JFileChooser.SELECTED_FILE_CHANGED_PROPERTY==e.getPropertyName()) {
//获取当前选中的文件
File picFile = (File) e.getNewValue();
//文件非空则预览
if (picFile!=null&&picFile.isFile()) {
try {
//获取Image对象
Image image = getToolkit().getImage(picFile.toURI().toURL());
Image newImage = image.getScaledInstance(400, 300, Image.SCALE_SMOOTH);
paint.setImage(newImage);
//重新绘制,实现图片预览
paint.repaint();
} catch (MalformedURLException e1) {
e1.printStackTrace();
}
}
}
}
}
在MyFileChooser中使用了setAccessory()方法来给选择器增加了一个辅助控件PaintPanel用来显示图片预览,代码如下:
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.JPanel;
public class PaintPanel extends JPanel{
/**
*
*/
private static final long serialVersionUID = 1L;
private Image image;
@Override
protected void paintComponent(Graphics arg0) {
//重写paint方法,绘制图片
super.paintComponent(arg0);
if (image!=null) {
arg0.drawImage(image, 0, 0, getWidth(), getHeight(), this);
}
}
public Image getImage() {
return image;
}
public void setImage(Image image) {
this.image = image;
}
}
再简单的写一个测试类,其中设置了文件选择器为常见的图片格式:jpg,jpeg,gif,png...同时,取消了所有文件的过滤器。
import java.awt.BorderLayout;
import java.awt.Desktop;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.filechooser.FileNameExtensionFilter;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import java.awt.event.ActionEvent;
public class MyFileChooserTest extends JFrame {
/**
*
*/
private static final long serialVersionUID = 1L;
private JPanel contentPane;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MyFileChooserTest frame = new MyFileChooserTest();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public MyFileChooserTest() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(0, 0));
setContentPane(contentPane);
JButton btnNewButton = new JButton("Choose a picture to open");//单击触发MyFileChooser
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
MyFileChooser chooser = new MyFileChooser();
chooser.setAcceptAllFileFilterUsed(false);//取消所有文件过滤器并设置新的图片文件过滤器
chooser.setFileFilter(new FileNameExtensionFilter("图片文件", "jpg","jpeg","gif","png"));
int option = chooser.showOpenDialog(null);
if (option==JFileChooser.APPROVE_OPTION) {
File file = chooser.getSelectedFile();//获取选中的文件
System.out.println(file.getAbsolutePath()+file.getName());//输出文件路径和名称
if (Desktop.isDesktopSupported()) {//判断是否支持Desktop
Desktop desktop = Desktop.getDesktop();
try {
desktop.open(file);//支持的条件下,调用默认的打开方式打开选中的文件
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
});
contentPane.add(btnNewButton, BorderLayout.SOUTH);
}
}
供自己回顾和大家参考,欢迎指证。