用JTable 实现日历

效果图:

主要思想：日历最核心的功能就是能显示某年某月对应的日期和星期几。因此只要实现传入具体的年份和月份，得到一组存放了日期的数组a[ ]即可。其中数组的大小设置成42，要考虑的问题是当月的第一天对应星期几。日期数组中的前七个，肯定包含了当月的第一天，把这一天找到，将“1”填入，后面的日期依次累加直到加完该月最后一天为止。

MyCalendar类：得到用于显示日期数组a[ ]

import java.util.Calendar;

public class MyCalendar {
String day[];
int year = 2020,month=0;

public String[] getDay() {
return day;
}
public void setDay(String[] day) {
this.day = day;
}
public int getYear() {
return year;
}
public void setYear(int year) {
this.year = year;
}
public int getMonth() {
return month;
}
public void setMonth(int month) {
this.month = month;
}
private boolean isLeapYear() {
if(this.year%4==0 && this.year%100!=0){
return true;
}else
if(this.year%400==0){
return true;
}else

return false;
}

//获得显示数组
public String[] getCalendar(){
Calendar calendar=Calendar.getInstance();
String a[]=new String[42];
calendar.set(year,month-1,1);
int weekday=calendar.get(Calendar.DAY_OF_WEEK)-1;
int day=0;
int days = 31;
if (this.month == 4 || this.month == 6 || this.month == 9 || this.month == 11)
days = 30;
if (this.month == 2 && isLeapYear())
days = 29;
if (this.month == 2 && !isLeapYear())
days = 28;

for(int i = weekday,n=1;i< weekday +days;i++){
a[i]=String.valueOf(n);
n++;
}
return a;
}

}

MyFrame类：创造显示面板，主要用到JTable。

public class MyFrame extends JFrame implements ActionListener {
//存储数据
MyCalendar calendar = new MyCalendar();
JComboBox choiceYear,choiceMonth;
JTable table = null;
JPanel root = new JPanel();
JLabel lyear, lmonth;

private Object[] name = {"日","一","二","三","四","五","六"};
private TableModel tableModel = new DefaultTableModel(name,6);

//    private static int row = 6;
//    private static int column = 7;

public MyFrame(String title) {
super(title);

this.setContentPane(root);
root.setLayout(new BorderLayout());
//年月选择栏
choiceYear=new JComboBox();
choiceMonth=new JComboBox();
lyear=new JLabel("年");
lmonth=new JLabel("月 ");
for(int i=1990;i<2050;i++)
choiceYear.addItem(i);
choiceYear.addActionListener(this);
for(int i=1;i<=12;i++)
choiceMonth.addItem(i);
choiceMonth.addActionListener(this);

JPanel pNorth=new JPanel();

pNorth.add(choiceYear);
pNorth.add(lyear);
pNorth.add(choiceMonth);
pNorth.add(lmonth);
root.add(pNorth,BorderLayout.NORTH);

// 表格初始化
setYearAndMonth( 1990, 1);

}

//设置年月日
public void setYearAndMonth(int y,int m){
calendar.setYear(y);
calendar.setMonth(m);
String day[]=calendar.getCalendar();
Vector<Object> rowData = new Vector<>();
int row = 0;
int column = 0;
for(int i = 0; i< 42; i++) {
row = i / 7;
column = i % 7;

tableModel.setValueAt(day[i], row, column);

}

// 创建 JTable，直接重写 isCellEditable()，设为不可编辑
table = new JTable(tableModel){
@Override
public boolean isCellEditable(int row, int column)
{
return false;
}
};
JScrollPane scrollPane = new JScrollPane(table);
root.add(scrollPane, BorderLayout.CENTER);

// 添加到主界面
table.setFillsViewportHeight(true);
table.setRowSelectionAllowed(true); // 整行选择
table.setRowHeight(30);
}

public void actionPerformed(ActionEvent e){

//选择年份
if (e.getSource()==choiceYear){
calendar.setYear((Integer) choiceYear.getSelectedItem());
String day[]=calendar.getCalendar();
Vector<Object> rowData = new Vector<>();
int row = 0;
int column = 0;
for(int i = 0; i< 42; i++) {
row = i / 7;
column = i % 7;

tableModel.setValueAt(day[i], row, column);

}
table = new JTable(tableModel){
@Override
public boolean isCellEditable(int row, int column)
{
return false;
}
};
JScrollPane scrollPane = new JScrollPane(table);
root.add(scrollPane, BorderLayout.CENTER);

// 添加到主界面
table.setFillsViewportHeight(true);
table.setRowSelectionAllowed(true); // 整行选择
table.setRowHeight(30);
}
//选择月份
else if (e.getSource()==choiceMonth){
calendar.setMonth((Integer) choiceMonth.getSelectedItem());
String day[]=calendar.getCalendar();
Vector<Object> rowData = new Vector<>();
int row = 0;
int column = 0;
for(int i = 0; i< 42; i++) {
row = i / 7;
column = i % 7;

tableModel.setValueAt(day[i], row, column);

}
}
table = new JTable(tableModel){
@Override
public boolean isCellEditable(int row, int column)
{
return false;
}
};
JScrollPane scrollPane = new JScrollPane(table);
root.add(scrollPane, BorderLayout.CENTER);

// 添加到主界面
table.setFillsViewportHeight(true);
table.setRowSelectionAllowed(true); // 整行选择
table.setRowHeight(30);    

}

}

ShowView类：用于显示窗口，照抄即可，无需理解。

import java.awt.Container;
import java.awt.FlowLayout;

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

public class ShowView
{
    private static void createGUI()
    {

        // 语法：因为MyFrame是JFrame的子类，所以可以这么写
        JFrame frame = new MyFrame("日历");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // 设置窗口的其他参数，如窗口大小
        frame.setSize(400, 300);

        // 显示窗口
        frame.setVisible(true);

    }

    public static void main(String[] args)
    {
        // 此段代码间接地调用了 createGUI()

        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run()
            {
                createGUI();
            }
        });

    }
}