在Java中如何开发简易电子日历_电子日历项目实战解析

import java.time.*;

public class CalendarUtils {
    public static int getFirstDayOfWeek(int year, int month) {
        YearMonth yearMonth = YearMonth.of(year, month);
        DayOfWeek dayOfWeek = yearMonth.atDay(1).getDayOfWeek();
        return dayOfWeek.getValue() % 7; // 返回 0=周日, 1=周一, ..., 6=周六
    }

    public static int getDaysInMonth(int year, int month) {
        return YearMonth.of(year, month).lengthOfMonth();
    }
}
  

public class ConsoleCalendar {
    public static void printCalendar(int year, int month) {
        System.out.printf("\n%10s %d\n", Month.of(month), year);
        System.out.println("日 一 二 三 四 五 六");

        int startDay = CalendarUtils.getFirstDayOfWeek(year, month);
        int days = CalendarUtils.getDaysInMonth(year, month);

        for (int i = 0; i < startDay; i++) {
            System.out.print("   ");
        }

        for (int day = 1; day <= days; day++) {
            System.out.printf("%2d ", day);
            if ((day + startDay) % 7 == 0) System.out.println();
        }
        System.out.println();
    }
}
  

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;

public class GUICalendar extends JFrame {
    private int year, month;
    private JLabel title;
    private JPanel dayPanel;

    public GUICalendar() {
        this.year = Year.now().getValue();
        this.month = 1;
        initUI();
    }

    private void initUI() {
        setTitle("简易电子日历");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        // 标题与按钮
        JPanel top = new JPanel(new FlowLayout());
        JButton prevBtn = new JButton("上一月");
        JButton nextBtn = new JButton("下一月");
        title = new JLabel("", SwingConstants.CENTER);
        updateTitle();

        prevBtn.addActionListener(this::prevMonth);
        nextBtn.addActionListener(this::nextMonth);

        top.add(prevBtn);
        top.add(title);
        top.add(nextBtn);
        add(top, BorderLayout.NORTH);

        // 日历显示区域
        dayPanel = new JPanel(new GridLayout(6, 7));
        refreshCalendar();
        add(dayPanel, BorderLayout.CENTER);

        pack();
        setLocationRelativeTo(null);
    }

    private void refreshCalendar() {
        dayPanel.removeAll();
        String[] weekdays = {"日", "一", "二", "三", "四", "五", "六"};
        for (String w : weekdays) {
            dayPanel.add(new JLabel(w, SwingConstants.CENTER));
        }

        int start = CalendarUtils.getFirstDayOfWeek(year, month);
        int days = CalendarUtils.getDaysInMonth(year, month);
        LocalDate today = LocalDate.now();

        for (int i = 0; i < start; i++) {
            dayPanel.add(new JLabel(""));
        }

        for (int d = 1; d <= days; d++) {
            JLabel label = new JLabel(String.valueOf(d), SwingConstants.CENTER);
            if (year == today.getYear() && month == today.getMonthValue() && d == today.getDayOfMonth()) {
                label.setOpaque(true);
                label.setBackground(Color.YELLOW);
            }
            dayPanel.add(label);
        }

        dayPanel.revalidate();
        dayPanel.repaint();
    }

    private void prevMonth(ActionEvent e) {
        month--;
        if (month < 1) {
            month = 12;
            year--;
        }
        updateTitle();
        refreshCalendar();
    }

    private void nextMonth(ActionEvent e) {
        month++;
        if (month > 12) {
            month = 1;
            year++;
        }
        updateTitle();
        refreshCalendar();
    }

    private void updateTitle() {
        title.setText(String.format("%d年%d月", year, month));
    }
}
  

public class Main {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            new GUICalendar().setVisible(true);
        });
    }
}