Java中JTextField或JTextArea右键弹出菜单

import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.io.IOException;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
import javax.swing.JSeparator;
import javax.swing.JTextField;
import javax.swing.KeyStroke;

public class JPopupTextField extends JTextField implements MouseListener ,ActionListener{

private static final long serialVersionUID = -406608462064697359L;
private JPopupMenu popupMenu=null;
private JMenuItem cutMenu=null,copyMenu=null,pasteMenu=null,selectAllMenu=null;

public JPopupTextField() {
  
   super();
        popupMenu=new JPopupMenu();
       
        cutMenu=new JMenuItem("Cut");
        copyMenu=new JMenuItem("Copy");
        pasteMenu=new JMenuItem("Paste");
        selectAllMenu=new JMenuItem("Select All");
       
        cutMenu.setAccelerator(KeyStroke.getKeyStroke('X', InputEvent.CTRL_MASK));
        copyMenu.setAccelerator(KeyStroke.getKeyStroke('C', InputEvent.CTRL_MASK));
        pasteMenu.setAccelerator(KeyStroke.getKeyStroke('V', InputEvent.CTRL_MASK));
        selectAllMenu.setAccelerator(KeyStroke.getKeyStroke('A', InputEvent.CTRL_MASK));
       
        cutMenu.addActionListener(this);
        copyMenu.addActionListener(this);
        pasteMenu.addActionListener(this);
        selectAllMenu.addActionListener(this);
       
        popupMenu.add(cutMenu);
        popupMenu.add(copyMenu);
        popupMenu.add(pasteMenu);
        popupMenu.add(new JSeparator());
        popupMenu.add(selectAllMenu);
       
        this.add(popupMenu);
        this.addMouseListener(this);
       
}

public void actionPerformed(ActionEvent e) {

        if(e.getSource()==copyMenu){
        this.copy();
        }
        if(e.getSource()==pasteMenu){
        this.paste();
        }
        if(e.getSource()==cutMenu){
        this.cut();
        }
        if(e.getSource()==selectAllMenu){
        this.selectAll();
        }
  
}

public void mousePressed(MouseEvent e) {
  
   popupMenuTrigger(e);
}

public void mouseReleased(MouseEvent e) {
  
   popupMenuTrigger(e);
}

public void mouseClicked(MouseEvent e) {}

public void mouseEntered(MouseEvent e) {}

public void mouseExited(MouseEvent e) {}

private void popupMenuTrigger(MouseEvent e){
  
   if(e.isPopupTrigger()){
   
    this.requestFocusInWindow();
   
    cutMenu.setEnabled(isAbleToCopyAndCut());
    copyMenu.setEnabled(isAbleToCopyAndCut());
    pasteMenu.setEnabled(isAbleToPaste());
    selectAllMenu.setEnabled(isAbleToSelectAll());
   
    popupMenu.show(this,e.getX()+3, e.getY()+3);
   }
}

private boolean isAbleToSelectAll(){

   return !("".equalsIgnoreCase(this.getText())||(null==this.getText()));
}

private boolean isAbleToCopyAndCut(){
  
   return (this.getSelectionStart()!=this.getSelectionEnd());
}

private boolean isAbleToPaste(){
  
   Transferable content = this.getToolkit().getSystemClipboard().getContents(this);
   try {
    return (content.getTransferData(DataFlavor.stringFlavor) instanceof String);
   } catch (UnsupportedFlavorException e) {
    e.printStackTrace();
    return false;
   } catch (IOException e) {
    e.printStackTrace();
    return false;
   }
}

}