java中ScrollPane 如何使用，最好有个小例子，简单直接的

代码里截出来的片断

//声明对象

JTextArea jtaContent = new JTextArea()

JPanel jpMain = new JPanel()

//设置textarea

jtaContent.setBorder(BorderFactory.createLoweredBevelBorder())

jtaContent.setText(null)

//用jtaContent创建JScrollPane对象

JScrollPane scroll = new JScrollPane(jtaContent)

scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED) //水平滚动条根据需要才显示

scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED) //垂直滚动条根据需要才显示

scroll.setPreferredSize(new Dimension(300, 200))

//添加到panel

jpMain.add(scroll)

你可以直接给textarea添加一个右键监听，当检测到右键事件后，显示一个d出菜单，d出菜单就是自己的顶一定义的功能了。

public class PopupMenu extends JFrame {

private JPopupMenu menu

private JTextArea text

public PopupMenu() {

JMenuItem m

MenuItemListener mil = new MenuItemListener()

menu = new JPopupMenu()

text = new JTextArea(15, 30)

m = new JMenuItem("Item1")

m.addActionListener(mil)

menu.add(m)

m = new JMenuItem("Item2")

m.addActionListener(mil)

menu.add(m)

m = new JMenuItem("Item3")

m.addActionListener(mil)

menu.add(m)

text.addMouseListener(new MouseListener() {

public void mouseClicked(MouseEvent e) {

}

public void mouseEntered(MouseEvent e) {

}

public void mouseExited(MouseEvent e) {

}

public void mousePressed(MouseEvent e) {

}

public void mouseReleased(MouseEvent e) {

if (e.isPopupTrigger()) {

menu.show(text, e.getX(), e.getY())

}

}

})

getContentPane().add(text)

}

private class MenuItemListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

text.setText(((JMenuItem) e.getSource()).getText())

}

}

public static void main(String[] args) {

PopupMenu frame = new PopupMenu()

frame.pack()

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)

frame.setVisible(true)

}

}

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