用Java设计日历软件 根据如下图，综合运用GUI编程、事件处理、Calendar类应用等知识设计一款月历，要求能通过输入（或选择）年月的方式正确显示当前月份的所有日期

以下是一个简单的Java月历软件的示例代码，可以根据输入的年份和月份来显示当月的所有日期：

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

public class CalendarApp extends JFrame implements ActionListener {
    private JLabel monthLabel;
    private JButton prevButton, nextButton;
    private JPanel monthPanel, daysPanel;
    private int currentYear, currentMonth;

    public CalendarApp() {
        setTitle("Java月历");
        setSize(400, 400);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        // 获取当前日期
        Calendar calendar = Calendar.getInstance();
        currentYear = calendar.get(Calendar.YEAR);
        currentMonth = calendar.get(Calendar.MONTH);

        // 构建界面
        monthLabel = new JLabel(getMonthName(currentMonth) + " " + currentYear);
        prevButton = new JButton("上个月");
        nextButton = new JButton("下个月");
        prevButton.addActionListener(this);
        nextButton.addActionListener(this);
        monthPanel = new JPanel(new FlowLayout());
        monthPanel.add(prevButton);
        monthPanel.add(monthLabel);
        monthPanel.add(nextButton);
        daysPanel = new JPanel(new GridLayout(0, 7));
        add(monthPanel, BorderLayout.NORTH);
        add(daysPanel, BorderLayout.CENTER);

        // 显示当前月份的所有日期
        showMonth(currentYear, currentMonth);
    }

    // 处理按钮事件
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == prevButton) {
            currentMonth--;
            if (currentMonth < 0) {
                currentMonth = 11;
                currentYear--;
            }
        } else if (e.getSource() == nextButton) {
            currentMonth++;
            if (currentMonth > 11) {
                currentMonth = 0;
                currentYear++;
            }
        }
        monthLabel.setText(getMonthName(currentMonth) + " " + currentYear);
        showMonth(currentYear, currentMonth);
    }

    // 获取月份名称
    private String getMonthName(int month) {
        String[] months = {"一月", "二月", "三月", "四月", "五月", "六月",
                           "七月", "八月", "九月", "十月", "十一月", "十二月"};
        return months[month];
    }

    // 显示指定年月的所有日期
    private void showMonth(int year, int month) {
        daysPanel.removeAll();

        Calendar calendar = Calendar.getInstance();
        calendar.set(year, month, 1);
        int firstDayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
        int lastDayOfMonth = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);

        for (int i = 1; i < firstDayOfWeek; i++) {
            daysPanel.add(new JLabel());
        }

        for (int i = 1; i <= lastDayOfMonth; i++) {
            JLabel label = new JLabel(String.valueOf(i));
            label.setHorizontalAlignment(SwingConstants.CENTER);
            daysPanel.add(label);
        }

        revalidate();
        repaint();
    }

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

在这个示例代码中，我们使用了Java Swing库来构建界面，使用了Calendar类来获取当前日期和处理日期相关的逻辑。在构建界面时，我们使用了JLabel、JButton和JPanel等组件，并使用了FlowLayout和GridLayout来控制布局。在处理按钮事件时，我们通过改变currentYear和currentMonth的值来更新月历的显示，然后调用showMonth方法来重新显示当前月份的所有日期。在showMonth方法中，我们使用了Calendar类来计算当前月份的第一天是星期几，以及当前月份有多少天，然后使用JLabel组件来显示所有日期。最后，我们调用revalidate和repaint方法来刷新界面。