简单日历

package GUI;
import java.awt.BorderLayout;
public class CalenderTrain extends JFrame implements ActionListener{
private String year_int;
private int month_int=0;
private boolean todayflag=false;
private JComboBox monthbox=new JComboBox();
private JComboBox yearbox=new JComboBox();
private JLabel year=new JLabel("年份:");
private JLabel month=new JLabel("月份:");
private JPanel top=new JPanel();
private JPanel main=new JPanel();
private JButton ok=new JButton("查看");
private JButton today=new JButton("今天");
private Date date=new Date();
private int now_year=date.getYear()+1900;
private int now_month=date.getMonth();
private JButton button[]=new JButton[7];
private  final String b[]=new String[]{
"日","一","二","三","四","五","六"};
private JButton bu[]=new JButton[42];
    public CalenderTrain(){
    for(int i=now_year-10;i<=now_year+20;i++){
    yearbox.addItem(i);
    }
    yearbox.setSelectedItem(now_year);
    for(int i=1;i<13;i++){
    monthbox.addItem(i);
    }
    monthbox.setSelectedItem(now_month+1);
    ok.addActionListener(this);
    today.addActionListener(this);
    top.add(year);
    top.add(yearbox);
    top.add(month);
    top.add(monthbox);
    top.add(ok);
    top.add(today);
    this.add(top,BorderLayout.NORTH);
    for(int i=0;i<button.length;i++){
    button[i]=new JButton(b[i]);
    main.add(button[i]);
    }
    for(int i=0;i<bu.length;i++){
    bu[i]=new JButton(i+"");
    main.add(bu[i]);
    }
    this.pain();
    main.setLayout(new GridLayout(7,7));
    this.add(main,BorderLayout.CENTER);
    this.setBounds(200, 200, 400, 400);
    this.setTitle("日历");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setVisible(true);
    }
    public void pain(){
    int day_week=0;
    int days=0;
    if(todayflag==true){
    year_int=now_year+"";
    month_int=now_month;
    }else{
    year_int=yearbox.getSelectedItem().toString();
    month_int=monthbox.getSelectedIndex();
    }
    int years=Integer.parseInt(year_int.trim())-1900;
    Date firstday=new Date(years,month_int,1);
    GregorianCalendar cal=new GregorianCalendar();
    cal.setTime(firstday);
    if(month_int==0||month_int==2||month_int==4||month_int==6||month_int==7||month_int==9||month_int==11){
    days=31;
    }else if(month_int==3||month_int==5||month_int==8||month_int==10){
    days=30;
    }else if(cal.isLeapYear(years)){//判断该年是否为闰年，是闰年，2月份为29天，不是闰年，2月份为28天
    days=29;
    }else{
    days=28;
    }
    int count=1;
    day_week=firstday.getDay();
//    System.out.println(month_int);
//    System.out.println(new Date().getMonth());
    for(int i=day_week;i<day_week+days;i++,count++){
    if((years==new Date().getYear())&&(month_int==new Date().getMonth())&&(new Date().getDate()+day_week-1==i)){
    bu[i].setForeground(Color.red);
    }else{
    bu[i].setForeground(Color.black);
    }
    bu[i].setText(count+"");
    }
    if(day_week!=0){
    for(int i=0;i<day_week;i++){
    bu[i].setText(" ");
    }
    for(int j=day_week+days;j<42;j++){
    bu[j].setText(" ");
    }
    }
    }
    public void actionPerformed(ActionEvent e){
    if(e.getSource()==today){
    todayflag=true;
    monthbox.setSelectedItem(now_month+1);
    yearbox.setSelectedItem(now_year);
    this.pain();
    }
    if(e.getSource()==ok){
    todayflag=false;
    this.pain();
    }
    }
public static void main(String[] args) {
CalenderTrain calendertrain=new CalenderTrain();
}

}