时间定位表达式－用于时间的加、减调整

来源：互联网发布：电脑椅推荐知乎编辑：程序博客网时间：2024/06/15 19:21

在笔者开发的应用中，经常会遇到用户对数据有按照时间进行查询或监视的需求。用户对此类需求往往是希望可以输入一个已当前时间为准，向前回溯或向后延展一定时间的一个时间段。时间段可以是一天、一周、一个月，也可以是十天、一百天、十周等。为可以灵活满足此类需求，笔者写了一个专门做时间定位运算的表达式－－“时间定位表达式”。其具体格式如下：

($Now|$CurrentYear|…) [(+|-) num(y|m|w|d|h|mi|s)]+

时间定位表达式分为两个部分，“($Now|$CurrentYear|…)”部分称为锚表达式，用于标定时间计算的起始点；“[(+|-) num(y|m|w|d|h|mi|s)]+”部分称为调整表达式，用于根据起始点调整计算时间。如：$Now+3m+5h -40mi+20s。表示以当前时间为基础，在当前月的基础上在加上3个月，在当前小时的基础上加上5小时，在当前分钟的基础上减去40分钟，在当前秒的基础上加上20秒。若当前时间为2013-9-11 14:35:45，计算后的时间为：2014-1-1118:56:05。

锚表达式的定位标记除$Now外，还有$CurrentYear，$CurrentMonth，$CurrentWeek，$CurrentDay，$CurrentHour，$CurrentMinute。若当前时间为2013-9-2214:23:38，则$Now的值为2013-9-22 14:23:38；$CurrentYear的值为2013-1-1 00:00:00，即$CurrentYear定位的时间为某年的1月1日零时；$CurrentMonth的值为2013-9-100:00:00，即$CurrentMonth定位的时间为某年某月的第1天的零时；$CurrentWeek的值为2013-9-16 00:00:00;$CurrentDay的值为2013-9-22 00:00:00，即$CurrentDay定位的时间为该天的零时；$CurrentHour的值为2013-9-2214:00:00，即$CurrentHour定位的时间为该时刻的整点；$CurrentMinute的值为2013-9-2214:23:00，即$CurrentMinute定位的时间为该分钟的整点时刻。

调整表达式的调整幅度后缀。y后缀表示年，m后缀表示月，w后缀表示周，d后缀表示天，h后缀表示小时，mi后缀表示分钟，s后缀表示秒。表达式支持“＋”和“－”两种运算操作。支持对某个时间单位的连加连减操作，如：$Now-12d+5d等。

另外，该表达式是大小写不敏感的，其实现代码如下，由于逻辑简单就不解释了，大家自己看吧：

public class TposExpression implements Serializable {

publicstaticfinal String CURRENT_YEAR ="$CURRENTYEAR";

publicstaticfinal String CURRENT_MONTH ="$CURRENTMONTH";

publicstaticfinal String CURRENT_WEEK ="$CURRENTWEEK";

publicstaticfinal String CURRENT_DAY ="$CURRENTDAY";

publicstaticfinal String CURRENT_HOUR ="$CURRENTHOUR";

publicstaticfinal String CURRENT_MINUTE ="$CURRENTMINUTE";

publicstaticfinal String CURRENT_POSITION ="$NOW";

public static final String[] expressionTypes =new String[] {

CURRENT_YEAR,CURRENT_MONTH,CURRENT_WEEK, CURRENT_DAY, CURRENT_HOUR,

CURRENT_MINUTE,CURRENT_POSITION

};

public staticfinalchar YEAR ='Y';

publicstaticfinal charMONTH ='M';

publicstaticfinal charDAY ='D';

publicstaticfinal charWEEK ='W';

publicstaticfinal charHOUR ='H';

publicstaticfinal charMINUTE ='I';// MI

publicstaticfinal charSECOND ='S';

publicstaticfinal charPLUS ='+';

publicstaticfinal charMINUS ='-';

protectedintexpressionTypeIndex;

protected StringanchorExpression;

protected StringadjustExpression;

public TposExpression(String expression) {

Validate.notEmpty(expression, "expression is empty!");

expression = expression.trim();

expressionTypeIndex = checkExpression(expression);

splitExression(expression);

}

protected int checkExpression(String expression) {

expression = expression.toUpperCase();

for (int i = 0; i <expressionTypes.length; i++) {

if (expression.startsWith(expressionTypes[i])) {

return i;

}

throw new IllegalArgumentException(

"Invalid expression! Should be started with '$CurrentYear',"

+ "'$CurrentMonth','$CurrentWeek','$CurrentDay','$CurrentHour','$CurrentMinute','$Now' ");

}

protected void splitExression(String expression) {

anchorExpression =expressionTypes[expressionTypeIndex];

adjustExpression = expression

.substring(expressionTypes[expressionTypeIndex].length());

adjustExpression =adjustExpression.toUpperCase();

}

public Date getDate() {

Calendar calendar = Calendar.getInstance();

anchor(calendar, expressionTypeIndex);

position(calendar, adjustExpression); // offset

return calendar.getTime();

}

//静态方法，指定起始时间和调整表达式，直接定位时间。该起始时间可以是锚表达式支持不了的任意时间

public static Date position(Date date, String adjustExpression) {

Validate.notNull(date, "date is null!");

Validate.notEmpty(adjustExpression,"adjustExpression is empty!");

adjustExpression = adjustExpression.toUpperCase();

Calendar calendar = Calendar.getInstance();

calendar.setTime(date);

position(calendar, adjustExpression);

return calendar.getTime();

}

protected static void position(Calendar calendar, String expression) {

char operate =' ', flag =' ';

int num = -1;

for (int i = 0; i < expression.length(); i++) {

char ch = expression.charAt(i);

if (ch ==' ')

continue;

if (ch ==PLUS || ch ==MINUS) {

operate = ch;

} else if (Character.isDigit(ch)) {

int j = i + 1;

for (; j < expression.length(); j++) {

ch = expression.charAt(j);

if (!Character.isDigit(ch)) {

break;

}

if (j == expression.length()) {

thrownew IllegalArgumentException("Invalid expression");

}

String sub = expression.substring(i, j);

num = Integer.valueOf(sub).intValue();

i = j - 1;

} else if (ch == YEAR || ch == MONTH || ch ==DAY || ch ==WEEK

|| ch == HOUR || ch ==SECOND) {

if (ch ==MONTH) {

if (i + 1 < expression.length() && expression.charAt(i + 1) ==MINUTE) {

ch = MINUTE;

i++;

}

flag = ch;

calc(calendar, operate, flag, num);

operate = ' ';

flag = ' ';

num = -1;

}

protected static void calc(Calendar calendar, char operate, char flag, int num) {

if (operate ==PLUS) {

plus(calendar, flag, num);

} else if (operate == MINUS) {

minus(calendar, flag, num);

} else {

throw new IllegalArgumentException("Invalid operate!");

}

protected static void plus(Calendar calendar, char flag, int num) {

switch (flag) {

case YEAR:

int year = calendar.get(Calendar.YEAR);

year += num;

calendar.set(Calendar.YEAR, year);

break;

case MONTH:

int month = calendar.get(Calendar.MONTH);

month += num;

calendar.set(Calendar.MONTH, month);

break;

case WEEK:

num *= 7;

case DAY:

int day = calendar.get(Calendar.DAY_OF_YEAR);

day += num;

calendar.set(Calendar.DAY_OF_YEAR, day);

break;

case HOUR:

int hour = calendar.get(Calendar.HOUR_OF_DAY);

hour += num;

calendar.set(Calendar.HOUR_OF_DAY, hour);

break;

case MINUTE:

int minute = calendar.get(Calendar.MINUTE);

minute += num;

calendar.set(Calendar.MINUTE, minute);

break;

case SECOND:

int second = calendar.get(Calendar.SECOND);

second += num;

calendar.set(Calendar.SECOND, second);

break;

default:

throw new IllegalArgumentException("Invalid flag!");

}

protected static void minus(Calendar calendar, char flag, int num) {

switch (flag) {

case YEAR:

int year = calendar.get(Calendar.YEAR);

year -= num;

calendar.set(Calendar.YEAR, year);

break;

case MONTH:

int month = calendar.get(Calendar.MONTH);

month -= num;

calendar.set(Calendar.MONTH, month);

break;

case WEEK:

num *= 7;

case DAY:

int day = calendar.get(Calendar.DAY_OF_YEAR);

day -= num;

calendar.set(Calendar.DAY_OF_YEAR, day);

break;

case HOUR:

int hour = calendar.get(Calendar.HOUR_OF_DAY);

hour -= num;

calendar.set(Calendar.HOUR_OF_DAY, hour);

break;

case MINUTE:

int minute = calendar.get(Calendar.MINUTE);

minute -= num;

calendar.set(Calendar.MINUTE, minute);

break;

case SECOND:

int second = calendar.get(Calendar.SECOND);

second -= num;

calendar.set(Calendar.SECOND, second);

break;

default:

throw new IllegalArgumentException("Invalid flag!");

}

protected static void anchor(Calendar calendar, int expressionTypeIndex) {

switch (expressionTypeIndex) {

case 0:

calendar.set(Calendar.MONTH, 0);

case 1:

calendar.set(Calendar.DAY_OF_MONTH, 1);

case 3:

calendar.set(Calendar.HOUR_OF_DAY, 0);

case 4:

calendar.set(Calendar.MINUTE, 0);

case 5:

calendar.set(Calendar.SECOND, 0);

calendar.set(Calendar.MILLISECOND, 0);

break;

case 2:

int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);

if (dayOfWeek == 1) {

calendar.set(Calendar.DAY_OF_YEAR,

calendar.get(Calendar.DAY_OF_YEAR) - 7);

}

calendar.set(Calendar.DAY_OF_WEEK, 2);// Monday

calendar.set(Calendar.HOUR_OF_DAY, 0);

calendar.set(Calendar.MINUTE, 0);

calendar.set(Calendar.SECOND, 0);

calendar.set(Calendar.MILLISECOND, 0);

break;

}

public String getAnchorExpression() {

returnanchorExpression;

}

public String getAdjustExpression() {

returnadjustExpression;

}

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