爱华网Calendar类是采用手工的方式取得--日期，可以通过此类精确到毫秒，此类的定义如下：
public abstract class Calendar extends Object
implements Serializable, Cloneable, Comparable
这个类本身是一个抽象类，抽象类要想实例化肯定使用子类：GregorianCalendar
package org.lxh.api.datedemo;
import java.util.Calendar;
import java.util.GregorianCalendar;
public class CalendarDemo {
public static void main(String[] args) {
Calendar calendar = new GregorianCalendar();
System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
System.out.println("MONTH: " + (calendar.get(Calendar.MONTH) +1));
System.out.println("DATE: " + calendar.get(Calendar.DATE));
System.out
.println("HOUR_OF_DAY: " +calendar.get(Calendar.HOUR_OF_DAY));
System.out.println("MINUTE: " +calendar.get(Calendar.MINUTE));
System.out.println("SECOND: " +calendar.get(Calendar.SECOND));
System.out
.println("MILLISECOND: " +calendar.get(Calendar.MILLISECOND));
}
}
但是现在有一个问题，如果每次取时间都按照这种方式取的话，那么得累死，那么能不能设计一个类，可以通过此
类直接取得时间呢，例如：现在给出了如下的一个接口：
package org.lxh.api.datedemo;
public interface DateTime {
public String getDate() ;
public String getDateTime() ;
public String getTimeStamp() ;
}
前面需要补0的问题需要注意，例如：01。
package org.lxh.api.datedemo;
import java.util.Calendar;
import java.util.GregorianCalendar;
public class DateTimeImpl implements DateTime {
private Calendar calendar;
public DateTimeImpl() {
this.calendar = new GregorianCalendar();
}
public String getDate() {
StringBuffer buf = new StringBuffer();
buf.append(calendar.get(Calendar.YEAR)).append("-");
buf.append(this.addZero((calendar.get(Calendar.MONTH) + 1),2)).append("-");
buf.append(this.addZero(calendar.get(Calendar.DATE), 2));
return buf.toString();
}
public String getDateTime() {
StringBuffer buf = new StringBuffer();
buf.append(calendar.get(Calendar.YEAR)).append("-");
buf.append(this.addZero((calendar.get(Calendar.MONTH) + 1),2)).append("-");
buf.append(this.addZero(calendar.get(Calendar.DATE), 2)).append("");
buf.append(this.addZero(calendar.get(Calendar.HOUR_OF_DAY),2)).append(":") ;
buf.append(this.addZero(calendar.get(Calendar.MINUTE),2)).append(":") ;
buf.append(this.addZero(calendar.get(Calendar.SECOND),2)).append(".") ;
buf.append(this.addZero(calendar.get(Calendar.MILLISECOND), 3));
return buf.toString();
}
@Override
public String getTimeStamp() {
StringBuffer buf = new StringBuffer();
buf.append(calendar.get(Calendar.YEAR));
buf.append(this.addZero((calendar.get(Calendar.MONTH) + 1),2));
buf.append(this.addZero(calendar.get(Calendar.DATE), 2));
buf.append(this.addZero(calendar.get(Calendar.HOUR_OF_DAY),2));
buf.append(this.addZero(calendar.get(Calendar.MINUTE), 2)) ;
buf.append(this.addZero(calendar.get(Calendar.SECOND), 2)) ;
buf.append(this.addZero(calendar.get(Calendar.MILLISECOND), 3));
return buf.toString();
}
private String addZero(int num, int len) {
StringBuffer buf = new StringBuffer();
buf.append(num);
while (buf.length() < len) {
buf.insert(0, 0);
}
return buf.toString();
}
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