处理java日期的一些操作

package yyf.java.util.DateTest;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

import org.junit.Test;

/**
* 对日期类的一些操作
*
* @author Yu Yufeng
*
*/
public class DateUse {
@Test
public void test() {
System.out.println("DateUse.test()");
}

/**
* 日期格式
*/
@Test
public void testFormate() {
Date date = new Date();
DateFormat f = new SimpleDateFormat("yyyy-MM-dd");
String dateStr = f.format(date);
System.out.println(dateStr);
}

/**
* 对时间的加减
*/
@Test
public void testDateModify() {
Date date = new Date();
Calendar cNow = Calendar.getInstance();
cNow.setTime(date);
System.out.println(cNow);
cNow.add(Calendar.DATE, -1);
Date now = cNow.getTime();
System.out.println(now);

}

/**
* 得到一天的时间 0~24
*/
@Test
public void testGetOneDay() {
Date date = new Date();//当前一天
Date res;
Calendar cNow = Calendar.getInstance();
cNow.setTime(date);
res = cNow.getTime();
cNow.set(Calendar.HOUR_OF_DAY, 0);
cNow.set(Calendar.SECOND, 0);
cNow.set(Calendar.MINUTE, 0);
cNow.set(Calendar.MILLISECOND, 0);
res = cNow.getTime();
System.out.println(res);
cNow.add(Calendar.DATE, -1);
res = cNow.getTime();
System.out.println(res);

}/**
* 得到一天之前七天
*/
@Test
public void testGet7DaysBefore() {
Date date = new Date();//当前一天
Date res;
Calendar cNow = Calendar.getInstance();
cNow.setTime(date);
res = cNow.getTime();
cNow.set(Calendar.HOUR_OF_DAY, 0);
cNow.set(Calendar.SECOND, 0);
cNow.set(Calendar.MINUTE, 0);
cNow.set(Calendar.MILLISECOND, 0);
res = cNow.getTime();
for(int i=0;i<7;i++){
cNow.add(Calendar.DATE, -1);
res = cNow.getTime();
System.out.println(res);
}

}
}