java - 在 Applet 中未接收焦点或窗口事件

Question

我有一个 Java Applet(使用 JApplet 类)，并且我试图在激活 Applet 窗口时获取事件。我尝试实现 WindowListener 和 FocusListener，但没有收到任何事件。我需要做什么才能确定小程序窗口是否已获得焦点？

这是我的测试代码:

public class AppletTest extends JApplet implements WindowListener, FocusListener {
    public void init() { 
//        addWindowListener(this); // Won't compile
        addFocusListener(this);
    }
    public void actionPerformed(ActionEvent event){
        Object source = event.getSource();
        String command = event.getActionCommand();
    }

    @Override
    public void focusGained(FocusEvent e) {
        System.out.println("focusGained");
    }
    @Override
    public void focusLost(FocusEvent e) {}

    @Override
    public void windowActivated(WindowEvent e) {
        System.out.println("windowActivated");
    }
    // Stub methods 
    @Override
    public void windowOpened(WindowEvent e) {}
    @Override
    public void windowClosing(WindowEvent e) {}
    @Override
    public void windowClosed(WindowEvent e) {}
    @Override
    public void windowIconified(WindowEvent e) {}
    @Override
    public void windowDeiconified(WindowEvent e) {}
    @Override
    public void windowDeactivated(WindowEvent e) {}
}

Answer 1

添加: setFocusable(true);

init 方法应该可以解决您的问题。