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(); }在此基础上添加滑动条

可以使用JScrollPane来包裹msgPanel，这样就可以自动添加滚动条了。具体实现可以参考下面的代码：

JScrollPane scrollPane = new JScrollPane(msgPanel);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
add(scrollPane, BorderLayout.CENTER);

这样就可以在msgPanel的高度超过容器高度时显示滚动条了。

相关问题

保留完整的原有功能的基础上，确保滚动条显示为最新的界面private void initMsgPanel(){ msgPanel=new JPanel(); msgPanel.setLayout(new BoxLayout(msgPanel, BoxLayout.Y_AXIS)); msgPanel.setBackground(Color.WHITE); JScrollPane scrollPane = new JScrollPane(msgPanel); scrollPane.setBounds(5,5,370,330); add(scrollPane); } 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); itemPanel.setPreferredSize(new Dimension(msgPanel.getWidth(),25)); itemPanel.add(msgLbl); FlowLayout layout = (FlowLayout) itemPanel.getLayout(); layout.setAlignment(align); msgPanel.add(itemPanel); msgPanel.updateUI(); }

为了确保滚动条显示为最新的界面，可以在添加消息后，将滚动条设置到最底部。修改后的代码如下：

private void initMsgPanel(){
    msgPanel=new JPanel();
    msgPanel.setLayout(new BoxLayout(msgPanel, BoxLayout.Y_AXIS));
    msgPanel.setBackground(Color.WHITE);

    JScrollPane scrollPane = new JScrollPane(msgPanel);
    scrollPane.setBounds(5,5,370,330);
    add(scrollPane);
}

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);
    itemPanel.setPreferredSize(new Dimension(msgPanel.getWidth(),25));
    itemPanel.add(msgLbl);

    FlowLayout layout = (FlowLayout) itemPanel.getLayout();
    layout.setAlignment(align);

    msgPanel.add(itemPanel);
    msgPanel.updateUI();

    // 将滚动条设置到最底部
    JScrollBar vertical = ((JScrollPane)msgPanel.getParent()).getVerticalScrollBar();
    vertical.setValue(vertical.getMaximum());
}

在msgAddToMsgPanel()方法的最后，添加了获取滚动条并将其设置到最底部的代码。这样就能保证每次添加消息后，滚动条都会自动滑动到最底部。

保留完整的原有功能的基础上，为msgPanel添加滑动条： 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); msgPanel.add(itemPanel); //更新界面 msgPanel.updateUI(); }

你可以使用JScrollPane来为msgPanel添加滑动条。具体实现方法如下：

1. 将msgPanel的布局方式设置为Boxlayout，以便支持纵向滚动条。
2. 创建一个JScrollPane对象，并将msgPanel添加到JScrollPane中。
3. 将JScrollPane添加到当前界面中。

修改后的代码如下：

private void initMsgPanel(){
    msgPanel=new JPanel();
    msgPanel.setLayout(new BoxLayout(msgPanel, BoxLayout.Y_AXIS));
    msgPanel.setBackground(Color.WHITE);
    
    JScrollPane scrollPane = new JScrollPane(msgPanel);
    scrollPane.setBounds(5,5,370,330);
    add(scrollPane);
}

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);
    itemPanel.setPreferredSize(new Dimension(msgPanel.getWidth(),25));
    itemPanel.add(msgLbl);

    FlowLayout layout = (FlowLayout) itemPanel.getLayout();
    layout.setAlignment(align);

    msgPanel.add(itemPanel);
    msgPanel.updateUI();
}