java实用程序设计100例（1-2）

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("2004", 5); //显示年份的文本域 Choice monthChoice = new Choice(); //月份选择下拉框 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[] = {"星期日", "星期一", "星期二", "星期三","星期四", "星期五", "星期六"}; String months[] = {"一月", "二月", "三月", "四月","五月", "六月", "七月", "八月", "九月","十月", "十一月", "十二月"}; 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); //得到系统年份 searchYear = calendar.get(Calendar.YEAR); //得到系统月份 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:")); 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; if (e.target==btUpdate){ searchMonth = monthChoice.getSelectedIndex(); //得到查询月份 searchYearInt = Integer.parseInt(tfYear.getText(), 10); //得到查询年份 if (searchYearInt > 1581) { searchYear = searchYearInt; } repaint(); //重绘屏幕 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; } }