贴上一期万年历的源代码，与君共享（160行，原创，虽然是简单的applet）

java source code

import java.applet.Applet;
import java.awt.*;
import java.util.*;

public class CalendarApplet extends Applet{

static final int TOP = 70;  //顶端距离
static final int CELLWIDTH=50,CELLHEIGHT = 30;  //单元格尺寸
static final int MARGIN = 3;  //边界距离
static final int FEBRUARY = 1;

TextField tfYear = new TextField("2011", 5); //显示年份的文本域
//Choice monthChoice = new Choice();  //月份选择下拉框
TextField tfMonth = new TextField("5");

Button btUpdate = new Button("更新");  //更新按钮
GregorianCalendar calendar=new GregorianCalendar(); //日历对象
Font smallFont = new Font("TimesRoman", Font.PLAIN, 15);  //显示小字体
Font bigFont = new Font("TimesRoman", Font.BOLD, 50);  //显示大字体
String days[] = {"Sun",	"Mon",	"Tue",	"Wed",	"Thu",	"Fri",	"Sat"};
String months[] = {" ","1", "2", "3", "4","5", "6", "7", "8", "9","10", "11", "12"};
int daysInMonth[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; //每个月的天数
int searchMonth,searchYear; //查询的年份及月份

public void init()
{
setBackground(Color.white);  //设置背景颜色
searchMonth = calendar.get(Calendar.MONTH); //得到系统月份
searchYear = calendar.get(Calendar.YEAR);	//得到系统年份
//   add(new Label(" 年:")); //增加组件到Applet
tfYear.setText(String.valueOf(searchYear)); //设置文本域文字
add(tfYear);
//   add(new Label(" 月:"));
tfMonth.setText(String.valueOf(searchMonth+1));//初始化月份搜索值为原来月份+1
add(tfMonth);
//    monthChoice.setFont(smallFont);  //设置月份选择下拉框的显示字体
//   for (int i = 0; i < 12; i++) {
//   	monthChoice.addItem(months[i]); //增加下拉框选项
//   }
//    monthChoice.select(searchMonth); //设置下拉框当前选择项
//    add(monthChoice);
add(btUpdate);
int componentCount=this.getComponentCount(); //得到Applet中的组件数量
for (int i=0;i<componentCount;i++){
getComponent(i).setFont(smallFont); //设置所有组件的显示字体
}
}

public void paint(Graphics g){
FontMetrics fontMetric;   //显示字体的FontMetrics对象
int fontAscent;
int dayPos;
int totalWidth, totalHeight; //总的宽度,高度
int numRows;  //行数
int xNum, yNum;   //水平和垂直方向单元格数量
int numDays;
String dayStr;	 //显示天数字符串
int margin;

g.setColor(Color.lightGray); //设置当前颜色
g.setFont(bigFont); //设置当前使用字体
g.drawString(searchYear+"年",60,TOP+70); //绘制字符串
g.drawString((searchMonth+1)+"月",200,TOP+130);

g.setColor(Color.black);
g.setFont(smallFont);
fontMetric = g.getFontMetrics(); 	//获取变量初值
fontAscent = fontMetric.getAscent();
dayPos = TOP + fontAscent / 2;
totalWidth = 7 * CELLWIDTH; 	//得到总的表格宽度
for (int i = 0; i < 7; i++) {
g.drawString(days[i], (CELLWIDTH-fontMetric.stringWidth(days[i]))/2 + i*CELLWIDTH,dayPos-20);  //绘制表格标题栏
}
numRows = getNumberRows(searchYear, searchMonth); //计算需要的行的数量
totalHeight = numRows * CELLHEIGHT; //得到总的表格高度
for (int i = 0; i <= totalWidth; i += CELLWIDTH) {
g.drawLine(i, TOP , i, TOP+ totalHeight); //绘制表格线
}
for (int i = 0, j = TOP ; i <= numRows; i++, j += CELLHEIGHT) {
g.drawLine(0, j, totalWidth, j); //绘制表格线
}
xNum = (getFirstDayOfMonth(searchYear, searchMonth) + 1) * CELLWIDTH - MARGIN;
yNum = TOP +  MARGIN + fontAscent;
numDays = daysInMonth[searchMonth] + ((calendar.isLeapYear(searchYear) && (searchMonth == FEBRUARY)) ? 1 : 0);
for (int day = 1; day <= numDays; day++) {
dayStr = Integer.toString(day);
g.drawString(dayStr, xNum - fontMetric.stringWidth(dayStr), yNum); 	//绘制字符串
xNum += CELLWIDTH;
if (xNum > totalWidth) {
xNum = CELLWIDTH - MARGIN;
yNum += CELLHEIGHT;
}
}
}

public boolean action(Event e, Object o){
int searchYearInt,searchMonthInt;
if (e.target==btUpdate){
//	searchMonth = monthChoice.getSelectedIndex();  //得到查询月份
searchMonthInt=Integer.parseInt(tfMonth.getText(), 10);
searchYearInt = Integer.parseInt(tfYear.getText(), 10);  //得到查询年份
if (searchYearInt > 1581)
{
searchYear = searchYearInt;
}
repaint();  //重绘屏幕
if((searchMonthInt>=1)&&(searchMonthInt<=12))		//月份大于等于1并且小于等于12
{
searchMonth=searchMonthInt-1;			//数组里面是从下标为0的数组开始，表示一月份，所以MonthInt-1
}
repaint();
return true;
}
return false;
}

private int getNumberRows(int year, int month) { //得到行数量
int firstDay;
int numCells;
if (year < 1582)
{ //年份小于1582年，则返回-1
return (-1);
}
if ((month < 0) || (month > 11)) {
return (-1);
}
firstDay = getFirstDayOfMonth(year, month); //计算月份的第一天

if ((month == FEBRUARY) && (firstDay == 0) && !calendar.isLeapYear(year)) {
return 4;
}
numCells = firstDay + daysInMonth[month];
if ((month == FEBRUARY) && (calendar.isLeapYear(year))) {
numCells++;
}
return ((numCells <= 35) ? 5 : 6); 	//返回行数
}

private int  getFirstDayOfMonth(int year, int month) {  //得到每月的第一天
int firstDay;
int i;
if (year < 1582) { //年份小于1582年,返回-1
return (-1);
}
if ((month < 0) || (month > 11)) { //月份数错误,返回-1
return (-1);
}
firstDay = getFirstDayOfYear(year);	//得到每年的第一天
for (i = 0; i < month; i++)
{
firstDay += daysInMonth[i]; //计算每月的第一天
}
if ((month > FEBRUARY) && calendar.isLeapYear(year))
{
firstDay++;
}
return (firstDay % 7);
}

private int getFirstDayOfYear(int year){ //计算每年的第一天
int leapYears;
int hundreds;
int fourHundreds;
int first;
if (year < 1582) { //如果年份小于1582年
return (-1); //返回-1
}
leapYears = (year - 1581) / 4;
hundreds = (year - 1501) / 100;
leapYears -= hundreds;
fourHundreds = (year - 1201) / 400;
leapYears += fourHundreds;
first=5 + (year - 1582) + leapYears % 7; //得到每年第一天
return first;
}
}