Swing组件（如JButton）的焦点问题。（留分没有用，散了）

Question

有分也不能浪费啊! 为什么不自己查javadoc?实现接口java.awt.FocusListener就可以了.

Answer 1

对不起, 上面写错了. 应该是java.awt.event.FocusListener顺便提一句, 与事件有关的类大部分在java.awt.event包里, 查JComponent没用.FocusListener接口有二个方法: focusGained(FocusEvent e), focusLost(FocusEvent e), 接收一个FocusEvent参数, 用来处理组件获得焦点和失去焦点的行为的.

Answer 2

JButton.addFocusListener();
focusGained(FocusEvent e); // 得到焦点时
focusLost(FocusEvent e);  // 失去焦点时
           

Answer 3

1、java中监听事件使用的是监听器模式，把要监听的组件向监听器注册，当事件发生事，监听器收到信息，调用相应的方法处理。
楼主所说的组件的监听器就是java.awt.event.FocusListener，负责具体处理事件的方法就是
focusGained(FocusEvent e), focusLost(FocusEvent e)。2、想重做GUI，有两种方法，一种是继承JButton，自己定义该类的具体实现，第二种就是调用已有的API改变按钮的外观。

Answer 4

to zxmzfbdc
1.我已经大概清楚了，一直不知道有FocusListener啊（汗...）
2.你能不能说清楚一点呢，比如我要改变点击按钮时的外观，可以重载paintComponent(Graphics g)方法，但获得焦点时的虚线框是在哪里画的呢？

Answer 5

java.awt.event.FocusListener改外观package Stockman.SystemFramework;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Style extends Frame{
        JButton java,mac,motif,win;
        public Style(){
                super("Toolbar Example(Sqing)");
                setSize(450,250);
                JPanel lnfPanel=new JPanel();
                lnfPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
                LnFListener lnfListener=new LnFListener(this);
                mac=new JButton("Mac");
                mac.addActionListener(lnfListener);
                java=new JButton("Metal");
                java.addActionListener(lnfListener);
                motif=new JButton("Motif");
                motif.addActionListener(lnfListener);
                win=new JButton("Windows");
                win.addActionListener(lnfListener);
                lnfPanel.add(mac);
                lnfPanel.add(java);
                lnfPanel.add(motif);
                lnfPanel.add(win);
                add(lnfPanel,BorderLayout.SOUTH);
        }
        public static void main(String args[]){
                Style style=new Style();
                style.setVisible(true);
        }
}
class LnFListener implements ActionListener{
        Frame frame;
        public LnFListener(Frame f){
                frame=f;
        }
        public void actionPerformed(ActionEvent e){
                String lnfName=null;
                if(e.getActionCommand().equals("Mac")){
                        lnfName="com.apple.mrj.swing.MacLookAndFeel";
                }
                else if(e.getActionCommand().equals("Metal")){
                        lnfName="javax.swing.plaf.metal.MetalLookAndFeel";
                }
                else if(e.getActionCommand().equals("Motif")){
                        lnfName="com.sun.java.swing.plaf.motif.MotifLookAndFeel";
                }
                else if(e.getActionCommand().equals("Windows")){
                        lnfName="com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
                }
                else{
                        System.err.println("Unreconized L&F request action:"+e.getActionCommand());
                        return;
                }
                try{
                        UIManager.setLookAndFeel(lnfName);
                        SwingUtilities.updateComponentTreeUI(frame);
                }
                catch(UnsupportedLookAndFeelException ex1){
                        System.err.println("Unsupported LookAndFeel:"+lnfName);
                }
                catch(ClassNotFoundException ex2){
                        System.err.println("LookAndFeel class not found:"+lnfName);
                }
                catch(InstantiationException ex3){
                        System.err.println("Could not load LookAndFeel:"+lnfName);
                }
                catch(IllegalAccessException ex4){
                        System.err.println("Cannot use LookAndFeel:"+lnfName);
                }
        }
}

Answer 6

zxmzfbdc(也速该把阿秃儿) 楼上说的不错！不过楼主你要是想知道更深的话，那你就必须去看jdk！
因为光靠说是说不明白的！你只要在jdk中去找FocusListener就可以了！

Answer 7

算了，结帖了，尤其感谢Dan1980