calendarpanel.java

此源码为机械工业出版社出版的《Java语言程序设计》第三版所配套的书中所有源代码。

// CalendarPanel.java: Display calendar for a month
import java.awt.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
import java.util.*;
import java.text.*;

public class CalendarPanel extends JPanel
{
  private int month;
  private int year;
  private Locale locale = Locale.getDefault();  // Default locale

  // The header label
  private JLabel jlblHeader = new JLabel(" ", JLabel.CENTER);

  // Labels to display day names and days
  private JLabel[] jlblDay = new JLabel[49];

  // MyCalendar instance
  private MyCalendar calendar = new MyCalendar();

  // Constructor
  public CalendarPanel()
  {
    // Panel jpDays to hold day names and days
    JPanel jpDays = new JPanel();
    jpDays.setLayout(new GridLayout(7, 1));
    for (int i=0; i<49; i++)
    {
      jpDays.add(jlblDay[i] = new JLabel());
      jlblDay[i].setBorder(new LineBorder(Color.black, 1));
      jlblDay[i].setHorizontalAlignment(JLabel.RIGHT);
      jlblDay[i].setVerticalAlignment(JLabel.TOP);
    }

    // Place header and calendar body in the panel
    this.setLayout(new BorderLayout());
    this.add(jlblHeader, BorderLayout.NORTH);
    this.add(jpDays, BorderLayout.CENTER);

    // Set current month, and year
    calendar = new MyCalendar();
    month = calendar.get(Calendar.MONTH)+1;
    year = calendar.get(Calendar.YEAR);

    // Show calendar
    showHeader();
    showDayNames();
    showDays();
  }

  // Update the header based on locale
  private void showHeader()
  {
    SimpleDateFormat sdf = new SimpleDateFormat("MMMM yyyy", locale);
    String header = sdf.format(calendar.getTime());
    jlblHeader.setText(header);
  }

  // Update the day names based on locale
  private void showDayNames()
  {
    DateFormatSymbols dfs = new DateFormatSymbols(locale);
    String dayNames[] = dfs.getWeekdays();

    // Set calendar days
    for (int i=0; i<7; i++)
    {
      jlblDay[i].setText(dayNames[i+1]);
      jlblDay[i].setHorizontalAlignment(JLabel.CENTER);
    }
  }

  // Display days
  public void showDays()
  {
    // Set the calendar to the first day of the
    // specified month and year
    calendar.set(Calendar.YEAR, year);
    calendar.set(Calendar.MONTH, month-1);
    calendar.set(Calendar.DATE, 1);

    // Get the day of the first day in a month
    int startingDayOfMonth = calendar.get(Calendar.DAY_OF_WEEK);

    // Fill the calendar with the days before this month
    MyCalendar cloneCalendar = (MyCalendar)calendar.clone();
    cloneCalendar.add(Calendar.DATE, -1);
 	  for (int i=0; i<startingDayOfMonth-1; i++)
    {
      jlblDay[i+7].setForeground(Color.gray);
      jlblDay[i+7].setText(
        cloneCalendar.daysInMonth()-startingDayOfMonth+2+i+"");
    }

    // Display days of this month
    for (int i=1; i<=calendar.daysInMonth(); i++)
    {
      jlblDay[i-2+startingDayOfMonth+7].setForeground(Color.black);
      jlblDay[i-2+startingDayOfMonth+7].setText(i+"");
    }

    // Fill the calendar with the days after this month
    int j = 1;
    for (int i=calendar.daysInMonth()-1+startingDayOfMonth+7;
      i<49; i++)
    {
      jlblDay[i].setForeground(Color.gray);
      jlblDay[i].setText(j++ + "");
    }

    showHeader();
  }

  // Getter method for month
  public int getMonth()
  {
    return month;
  }

  // Setter method for month
  public void setMonth(int newMonth)
  {
    month = newMonth;
    showDays();
  }

  // Getter method for year
  public int getYear()
  {
    return year;
  }

  // Setter method for year
  public void setYear(int newYear)
  {
    year = newYear;
    showDays();
  }

  // Set a new locale
  public void setLocale(Locale newLocale)
  {
    locale = newLocale;
    showHeader();
    showDayNames();
  }
}