private void initMsgPanel(){ /* msgPanel=new JPanel(); msgPanel.setBounds(5,5,370,330); msgPanel.setBackground(Color.WHITE); add(msgPanel);} private void msgAddToMsgPanel(String msg,int align){ System.out.println("==========msgAddToMsgPanel==========="+msg); JLabel msgLbl=new JLabel(msg,SwingConstants.CENTER); msgLbl.setForeground(Color.decode("#61565A")); msgLbl.setBackground(Color.decode("#BACCD9")); msgLbl.setSize(50,25); msgLbl.setBorder(BorderFactory.createLineBorder(Color.getColor("#8FB2C9"),2,true)); msgLbl.setOpaque(true);//设置不透明 JPanel itemPanel=new JPanel(); itemPanel.setBackground(Color.WHITE); //将每一条消息所在的面板宽度，和消息面板的面板宽度相同 itemPanel.setPreferredSize(new Dimension(msgPanel.getWidth(),25)); itemPanel.add(msgLbl); //设置左右对齐 FlowLayout layout = (FlowLayout) itemPanel.getLayout(); layout.setAlignment(align); msgPanel.add(itemPanel); //更新界面 msgPanel.updateUI(); }，使消息能正常显示的同时让消息面板能拥有垂直滑动条

您可以将msgPanel放入一个带有垂直滚动条的JScrollPane中，以使其具有垂直滑动条。以下是修改后的代码：

private JScrollPane msgScrollPane;
private void initMsgPanel(){         
   msgPanel=new JPanel();         
   msgPanel.setBackground(Color.WHITE);         
   msgScrollPane = new JScrollPane(msgPanel, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);         
   msgScrollPane.setBounds(5,5,370,330);         
   add(msgScrollPane);      
}

这样，msgPanel就能够具有垂直滑动条了，并且您可以通过msgScrollPane对象来操作滚动条。同时，您需要修改msgAddToMsgPanel方法中的代码，将消息添加到msgPanel中而不是添加到itemPanel中。

private void msgAddToMsgPanel(String msg,int align){         
   System.out.println("==========msgAddToMsgPanel==========="+msg);         
   JLabel msgLbl=new JLabel(msg,SwingConstants.CENTER);         
   msgLbl.setForeground(Color.decode("#61565A"));         
   msgLbl.setBackground(Color.decode("#BACCD9"));         
   msgLbl.setSize(50,25);         
   msgLbl.setBorder(BorderFactory.createLineBorder(Color.getColor("#8FB2C9"),2,true));         
   msgLbl.setOpaque(true);//设置不透明          
   
   JPanel itemPanel=new JPanel();         
   itemPanel.setBackground(Color.WHITE);         
   //将每一条消息所在的面板宽度，和消息面板的面板宽度相同         
   itemPanel.setPreferredSize(new Dimension(msgPanel.getWidth(),25));         
   itemPanel.add(msgLbl);          
   //设置左右对齐         
   FlowLayout layout = (FlowLayout) itemPanel.getLayout();         
   layout.setAlignment(align);          
   
   msgPanel.add(itemPanel);          
   //更新界面         
   msgScrollPane.getVerticalScrollBar().setValue(msgScrollPane.getVerticalScrollBar().getMaximum());     
}

这样，消息就能正常显示，并且能够拥有垂直滑动条了。