好了,来看我在Common Lang中最后要讲的一个包:org.apache.commons.lang.time。这个包里面包含了如下5个类:
DateFormatUtils – 提供格式化日期和时间的功能及相关常量;
DateUtils – 在Calendar和Date的基础上提供更方便的访问;
DurationFormatUtils – 提供格式化时间跨度的功能及相关常量;
FastDateFormat – 为java.text.SimpleDateFormat提供一个的线程安全的替代类;
StopWatch – 是一个方便的计时器。
我们还是在一个例子中来看上述各个类的用法吧:
package sean.study.jakarta.commons.lang;
import java.util.Calendar;
import java.util.Date;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.time.DateFormatUtils;
import org.apache.commons.lang.time.DateUtils;
import org.apache.commons.lang.time.FastDateFormat;
import org.apache.commons.lang.time.StopWatch;
public class DateTimeUsage {
public static void main(String[] args) {
demoDateUtils();
demoStopWatch();
}
public static void demoDateUtils() {
System.out.println(StringUtils.center(" demoDateUtils ", 30, "="));
Date date = new Date();
String isoDateTime = DateFormatUtils.ISO_DATETIME_FORMAT.format(date);
String isoTime = DateFormatUtils.ISO_TIME_NO_T_FORMAT.format(date);
FastDateFormat fdf = FastDateFormat.getInstance("yyyy-MM");
String customDateTime = fdf.format(date);
System.out.println("ISO_DATETIME_FORMAT: " + isoDateTime);
System.out.println("ISO_TIME_NO_T_FORMAT: " + isoTime);
System.out.println("Custom FastDateFormat: " + customDateTime);
System.out.println("Default format: " + date);
System.out.println("Round HOUR: " + DateUtils.round(date, Calendar.HOUR));
System.out.println("Truncate HOUR: " + DateUtils.truncate(date, Calendar.HOUR));
System.out.println();
}
public static void demoStopWatch() {
System.out.println(StringUtils.center(" demoStopWatch ", 30, "="));
StopWatch sw = new StopWatch();
sw.start();
operationA();
sw.stop();
System.out.println("operationA used " + sw.getTime() + " milliseconds.");
System.out.println();
}
public static void operationA() {
try {
Thread.sleep(999);
}
catch (InterruptedException e) {
// do nothing
}
}
}
以下是运行结果:
======= demoDateUtils ========
ISO_DATETIME_FORMAT: 2005-08-01 T12:41:51
ISO_TIME_NO_T_FORMAT: 12:41:51
Custom FastDateFormat: 2005-08
Default format: Mon Aug 01 12:41:51 CST 2005
Round HOUR: Mon Aug 01 13:00:00 CST 2005
Truncate HOUR: Mon Aug 01 12:00:00 CST 2005
======= demoStopWatch ========
operationA used 1000 milliseconds.
具体的调用细节和完整的API请参阅Commons Lang的Javadoc。