我是 Java 新手。我需要在我的项目中使用 MDI。当用户在菜单栏中单击“打开”时，会添加内部框架，并且应该在顶部全屏显示。打开时，我仍然无法使其全屏显示。同样在我的代码中，如果我从“AddNote”方法中删除以下行，我将看不到内部框架。在逻辑上JDesktop应该在表单打开时添加。
JDesktopPane desktop = new JDesktopPane();
有我的代码：
package MyPackage;
import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import java.io.*;
import java.awt.Dimension;
import java.awt.FlowLayout;
public class MainForm extends JFrame implements ActionListener {
private JMenuItem cascade = new JMenuItem("Cascade");
private int numInterFrame=0;
private JDesktopPane desktop=null;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run()
{
new MainForm();
}
});
}
public MainForm(){
super("Example");
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
// Name the JMenu & Add Items
JMenu menu = new JMenu("File");
menu.add(makeMenuItem("Open"));
menu.add(makeMenuItem("Save"));
menu.add(makeMenuItem("Quit"));
// Add JMenu bar
JMenuBar menuBar = new JMenuBar();
menuBar.add(menu);
//menuBar.add(menuWindow);
setJMenuBar(menuBar);
this.setMinimumSize(new Dimension(400, 500));
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLayout(new BorderLayout());
this.setExtendedState(JFrame.MAXIMIZED_BOTH);
JDesktopPane desktop = new JDesktopPane();
this.add(desktop, BorderLayout.CENTER);
setVisible(true);
}
public void actionPerformed(ActionEvent e) {
// Menu item actions
String command = e.getActionCommand();
if (command.equals("Quit")) {
System.exit(0);
} else if (command.equals("Open")) {
// Open menu item action
JFileChooser fileChooser = new JFileChooser();
int returnVal = fileChooser.showOpenDialog(MainForm.this);
if (returnVal == fileChooser.APPROVE_OPTION) {
numInterFrame=numInterFrame+1;
File file = fileChooser.getSelectedFile();
AddNote(numInterFrame);
// Load file
} else if (returnVal == JFileChooser.CANCEL_OPTION ) {
// Do something else
}
}
else if (command.equals("Save")) {
// Save menu item action
System.out.println("Save menu item clicked");
}
}
private JMenuItem makeMenuItem(String name) {
JMenuItem m = new JMenuItem(name);
m.addActionListener(this);
return m;
}
private void AddNote(int index){
JDesktopPane desktop = new JDesktopPane();
JInternalFrame internalFrame = new JInternalFrame("PDFAnnotation" + index, true, true, true, true);
internalFrame.setBounds(0, 0, 600, 100);
desktop.add(internalFrame);
PDFPanel p=new PDFPanel();
JPanel e =p.getJPanel();
internalFrame.add(e, BorderLayout.CENTER);
internalFrame.setVisible(true);
this.add(desktop, BorderLayout.CENTER);
/* Dimension size = desktop.getSize();
int w = size.width ;
int h = size.height ;
int x=0;
int y=0;
desktop.getDesktopManager().resizeFrame(internalFrame, x, y, w, h);*/
}
}