import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.util.Date;
import java.util.GregorianCalendar;

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Calender extends JFrame implements ActionListener, ItemListener {

	/**
	 * 實現簡單的日歷功能
	 * 
	 * @author Jadie version 1.0 2007/12/29
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public static void main(String args[]) {
		try {
			Calender frame = new Calender();
			frame.setVisible(true);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private Date date = new Date();

	private GregorianCalendar gregorianCalendar = new GregorianCalendar();

	private String[] stringWeek = new String[] { "SUN", "MON", "TUE", "WED",
			"THU", "FRI", "SAT" };

	private String[] stringWeekCn = new String[] { "星期天", "星期一", "星期二", "星期三",
			"星期四", "星期五", "星期六" };

	private String[] stringMonth = new String[] { "Jan", "Feb", "Mar", "Apr",
			"May", "Jun", "Jul", "Aug", "Sept", "Oct", "Nov", "Dec" };

	private String[] strSysTime = new String[6];
	// 存儲當前日期信息
	private String[] strSysNowTime = new String[6];
	// 存儲運行時日期信息
	private JButton[] buttonDay = new JButton[42];

	private JButton[] buttonWeek = new JButton[7];

	private JLabel labelMonth = new JLabel();

	private JButton buttonToday = new JButton();

	private JButton buttonLastMonth = new JButton();

	private JButton buttonNextMonth = new JButton();

	private JComboBox comboYear = new JComboBox();

	private JComboBox comboMonth = new JComboBox();

	public Calender() {
		super("萬年歷---156制作");
		getContentPane().setLayout(new GridLayout(8, 7, 3, 5));
		setBounds(250, 200, 530, 360);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		comboYear.setForeground(new Color(0, 0, 255));
		comboYear.setFont(new Font("", Font.PLAIN, 14));
		for (int y = 1900; y < 2101; y++) {
			comboYear.addItem("  " + new Integer(y).toString());
		}
		getContentPane().add(comboYear);
		comboYear.addItemListener(this);

		final JLabel labelYear = new JLabel();
		labelYear.setForeground(Color.BLUE);
		labelYear.setFont(new Font("新宋體", Font.PLAIN, 14));
		getContentPane().add(labelYear);
		labelYear.setText("    年");

		comboMonth.setForeground(new Color(0, 0, 255));
		comboMonth.setFont(new Font("", Font.PLAIN, 14));
		for (int m = 1; m < 13; m++) {
			comboMonth.addItem("     " + new Integer(m).toString());
		}
		getContentPane().add(comboMonth);
		comboMonth.addItemListener(this);

		getContentPane().add(labelMonth);
		labelMonth.setForeground(Color.BLUE);
		labelMonth.setFont(new Font("新宋體", Font.PLAIN, 14));
		labelMonth.setText("    月");

		getContentPane().add(buttonLastMonth);
		buttonLastMonth.setForeground(Color.BLUE);
		buttonLastMonth.setFont(new Font("新宋體", Font.PLAIN, 14));
		buttonLastMonth.setText("上月");
		buttonLastMonth.addActionListener(this);

		getContentPane().add(buttonToday);
		buttonToday.setForeground(Color.BLUE);
		buttonToday.setFont(new Font("新宋體", Font.PLAIN, 14));
		buttonToday.setText("今天");
		buttonToday.addActionListener(this);

		getContentPane().add(buttonNextMonth);
		buttonNextMonth.setForeground(Color.BLUE);
		buttonNextMonth.setFont(new Font("新宋體", Font.PLAIN, 14));
		buttonNextMonth.setText("下月");
		buttonNextMonth.addActionListener(this);

		for (int i = 0; i < 7; i++) {
			buttonWeek[i] = new JButton();
			if (i == 0 || i == 6) {
				buttonWeek[i].setForeground(Color.RED);
			} else {
				buttonWeek[i].setForeground(Color.BLUE);
			}
			buttonWeek[i].setFont(new Font("新宋體", Font.PLAIN, 12));
			buttonWeek[i].setText(stringWeekCn[i]);
			getContentPane().add(buttonWeek[i]);
		}

		for (int i = 0; i < 42; i++) {
			buttonDay[i] = new JButton();
			buttonDay[i].setText("");
			getContentPane().add(buttonDay[i]);
		}
		this.setResizable(false);
		getSysNowTimeInfo();
		setNowDate();
		setNowDate();
	}

	public void setSysDate(int year, int month) {
		// 將日期設置為year年month月1日
		gregorianCalendar.set(year, month, 1);
	}

	public void actionPerformed(ActionEvent ae) {
		if (ae.getSource() == buttonToday) {
			setNowDate();
			setNowDate();
		} else if (ae.getSource() == buttonLastMonth) {
			setDate(-1);
		} else {
			setDate(1);
		}
	}

	public void itemStateChanged(ItemEvent arg0) {
		setDate(0);
	}

	public void getSysNowTimeInfo() {
		// 得到程序運行時的時間信息并存儲在字符串數組strSysNowTime中
		date = gregorianCalendar.getTime();
		strSysNowTime = (date + "").split(" ");
	}

	public void getSysTimeInfo() {
		// 得到系統當前的時間信息并存儲在字符串數組strSysTime中
		date = gregorianCalendar.getTime();
		strSysTime = (date + "").split(" ");
	}

	public int getNowMonth() {
		int month = 0;
		for (int i = 0; i < 12; i++) {
			if (strSysNowTime[1].equalsIgnoreCase(stringMonth[i])) {
				month = i;
				break;
			}
		}
		return month;
	}

	public int weekStrat(String strWeek) {
		// 返回字符串strWeek與星期中的第幾天匹配，SUN為第一天
		int strat = 0;
		for (int i = 0; i < 7; i++) {
			if (strWeek.equalsIgnoreCase(stringWeek[i])) {
				strat = i;
				break;
			}
		}
		return strat;
	}

	public void setNowDate() {
		// 將時間設置為程序運行時的時間
		setSysTime(getNowYear(), getNowMonth());
		getSysTimeInfo();
		setDayNull();
		getDay(getMonthDays(getNowYear(), getNowMonth() - 1), getMonthDays(
				getNowYear(), getNowMonth()), weekStrat(strSysTime[0]),
				getNowDay());
		comboYear.setSelectedIndex(getNowYear() - 1900);
		comboMonth.setSelectedIndex(getNowMonth());
	}

	public void setDate(int move) {
		// 將時間設置為選中的年月增加move個月之后的時間
		setSysTime(getYear(), getMonth() + move);
		getSysTimeInfo();
		setDayNull();
		getDay(getMonthDays(getYear(), getMonth() + move - 1), getMonthDays(
				getYear(), getMonth() + move), weekStrat(strSysTime[0]), -1);
		if (move != 0) {
			if (getMonth() == 0 && move < 0) {
				move = 11;
				comboYear.setSelectedIndex(getYear() - 1901);
			} else if (getMonth() == 11 && move > 0) {
				move = -11;
				comboYear.setSelectedIndex(getYear() - 1899);
			} else {
				comboYear.setSelectedIndex(getYear() - 1900);
			}
			comboMonth.setSelectedIndex(getMonth() + move);
		}
	}

	public void setSysTime(int year, int month) {
		gregorianCalendar.set(year, month, 1);
	}

	public int getNowYear() {
		return Integer.parseInt(strSysNowTime[5]);
	}

	public int getNowDay() {
		return Integer.parseInt(strSysNowTime[2]);
	}

	public int getYear() {
		return comboYear.getSelectedIndex() + 1900;
	}

	public int getMonth() {
		return comboMonth.getSelectedIndex();
	}

	public void setDayNull() {
		for (int d = 0; d < 42; d++) {
			buttonDay[d].setText("");
		}
	}

	public void getDay(int lastMonDays, int monthDays, int startWeek, int day) {
		// 設置日期顏色并打印
		for (int d = 0; d < startWeek + 1; d++) {
			buttonDay[d].setForeground(Color.GRAY);
			buttonDay[d].setText((lastMonDays - startWeek) + d + 1 + "");
		}
		for (int d = startWeek; d < startWeek + monthDays; d++) {
			if ((d - startWeek + 1) == day) {
				buttonDay[d].setForeground(Color.blue);
			} else if (d % 7 == 0 || d % 7 == 6) {
				buttonDay[d].setForeground(Color.RED);
			} else {
				buttonDay[d].setForeground(Color.BLACK);
			}

			buttonDay[d].setText(d - startWeek + 1 + "");
		}
		for (int d = monthDays + startWeek; d < 42; d++) {
			buttonDay[d].setForeground(Color.GRAY);
			buttonDay[d].setText(d - (monthDays + startWeek) + 1 + "");
		}
	}

	public int getMonthDays(int year, int month) {
		// 返回year年month月的天數
		switch (month) {
		case 3:
		case 5:
		case 8:
		case 10:
			return 30;
		case 1:
			if (gregorianCalendar.isLeapYear(year)) {
				return 29;
			} else {
				return 28;
			}
		default:
			return 31;
		}
	}
}