用Java.swing 写一个日历

好的，以下是一个简单的Java Swing日历实现：

import javax.swing.*;
import java.awt.*;
import java.util.Calendar;
import java.util.GregorianCalendar;

public class CalendarApp extends JFrame {
    private JLabel monthLabel;
    private JPanel monthPanel;
    private JPanel dayPanel;
    private JLabel[] dayLabels;

    public CalendarApp() {
        setTitle("Calendar");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        // 创建月份标签
        monthLabel = new JLabel();
        monthLabel.setHorizontalAlignment(SwingConstants.CENTER);
        add(monthLabel, BorderLayout.NORTH);

        // 创建月份面板
        monthPanel = new JPanel(new GridLayout(0, 7));
        add(monthPanel, BorderLayout.CENTER);

        // 创建日期面板
        dayPanel = new JPanel(new GridLayout(0, 7));
        add(dayPanel, BorderLayout.SOUTH);

        // 创建日期标签
        dayLabels = new JLabel[42];
        for (int i = 0; i < dayLabels.length; i++) {
            dayLabels[i] = new JLabel();
            dayLabels[i].setHorizontalAlignment(SwingConstants.CENTER);
            dayPanel.add(dayLabels[i]);
        }

        // 设置窗口大小并显示
        setSize(400, 300);
        setVisible(true);

        // 更新日历
        updateCalendar();
    }

    private void updateCalendar() {
        // 获取当前月份和年份
        Calendar calendar = new GregorianCalendar();
        int month = calendar.get(Calendar.MONTH);
        int year = calendar.get(Calendar.YEAR);

        // 设置月份标签
        monthLabel.setText((month + 1) + "/" + year);

        // 清除日历
        for (int i = 0; i < dayLabels.length; i++) {
            dayLabels[i].setText("");
        }

        // 获取当前月份的第一天
        calendar.set(Calendar.DAY_OF_MONTH, 1);
        int firstDayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);

        // 设置月份面板
        String[] daysOfWeek = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
        for (int i = 0; i < daysOfWeek.length; i++) {
            JLabel label = new JLabel(daysOfWeek[i]);
            label.setHorizontalAlignment(SwingConstants.CENTER);
            monthPanel.add(label);
        }
        for (int i = 1; i < firstDayOfWeek; i++) {
            monthPanel.add(new JLabel());
        }
        for (int i = 1; i <= calendar.getActualMaximum(Calendar.DAY_OF_MONTH); i++) {
            JLabel label = new JLabel(Integer.toString(i));
            label.setHorizontalAlignment(SwingConstants.CENTER);
            monthPanel.add(label);
        }
    }

    public static void main(String[] args) {
        new CalendarApp();
    }
}

这个日历应用程序使用了Java的Swing组件和Calendar类来生成日历。它包括一个月份标签、一个月份面板和一个日期面板。在月份面板中，我们将星期几的名称添加到第一行，并在第二行添加第一个日期。在日期面板中，我们添加了每个日期的标签，并将它们按照星期几的顺序排列。