java 日期类型转换

import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

/**
* 工具类 用于与date类型相关的类型转换
*
* @author vinegar
*
*/
public class DateSwitch {

/**
* 将Calendar类型转成String类型 需要时分秒
*
* @param switchCalendar
*/
public static String SwitchString(Calendar cal) {
// TODO Auto-generated method stub
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateStr = df.format(cal.getTime());
return dateStr;
}

/**
* 将String 类型转换成Calendar类型 需要时分秒
*
* @param str
* @return
*/
public static Calendar SwitchCalendar(String str) {
// TODO Auto-generated method stub
String time=str.substring(0, 10)+" "+str.substring(11, 18);
Calendar cal = new GregorianCalendar();
Date data = null;
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try {
data = sdf.parse(time);
// System.out.println(data);
} catch (Exception e) {
e.printStackTrace();
}
cal.setTime(data);
// System.out.println(cal);
return cal;
}

/**
* 将String 类型转换成Calendar类型 不需要时分秒
*
* @param str
* @return
*/
public static Calendar SwitchCalendar2(String str) {
// TODO Auto-generated method stub
Calendar cal = new GregorianCalendar();
Date data = null;
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
try {
data = sdf.parse(str);
// System.out.println(data);
} catch (Exception e) {
e.printStackTrace();
}
cal.setTime(data);
// System.out.println(cal);
return cal;
}

/**
* 将Calendar类型转换成java.sql.Date类型
*
* @param cal
* @return
*/
public static java.sql.Date SwitchSqlDate(Calendar cal) {
Date date = cal.getTime();
Timestamp datetime = new Timestamp(date.getTime());
java.sql.Date time = new java.sql.Date(datetime.getTime());
System.out.println(time);
return time;
}

/**
* 获取当前日期的前一天
*
* @return
*/
public static String CatchBeforeDay() {
// 获取当前日期的前一天 System.currentTimeMillis()-24*60*60*1000(一天的毫秒数)
Date date = new Date(System.currentTimeMillis() - 86400000);
// System.out.println("当前天:"+System.currentTimeMillis());
// System.out.println("前一天:"+(System.currentTimeMillis()-86400000));
java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(
"yyyy-MM-dd");
String time = sdf.format(date);
return time;
}

/**
* 当天日期
*
* @return
*/
public static String CatchDay() {
java.util.Date date = new java.util.Date();
java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(
"yyyy-MM-dd");
String time = sdf.format(date);
System.out.println("今天日期:"+time);
return time;
}

/**
* 获取当前日期的后一天
*
* @return
*/
public static String CatchLaterDay() {
// 获取当前日期的后一天 System.currentTimeMillis()-24*60*60*1000(一天的毫秒数)
java.util.Date date = new java.util.Date(
System.currentTimeMillis() + 86400000);
// System.out.println("当前天:"+System.currentTimeMillis());
// System.out.println("后一天:"+(System.currentTimeMillis()-86400000));
java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(
"yyyy-MM-dd");
String time = sdf.format(date);
System.out.println("明天日期:"+time);
return time;
}

/**
* 获取当前月的最后一天
*
* @return
*/
public static String CatchLastDay() {
Calendar cal = Calendar.getInstance();
// 把日期设置为当月第一天
cal.set(Calendar.DATE, 1);
// 日期回滚一天，也就是最后一天
cal.roll(Calendar.DATE, -1);
// 获取当前月的天数
int MaxDay = cal.get(Calendar.DATE);
// 获取当前月份
int nowMonth = cal.get(Calendar.MONTH) + 1;
String NowMonth;
if (nowMonth < 10) {
NowMonth = "0" + nowMonth;
} else {
NowMonth = nowMonth + "";
}
// 获取当前年份
int NowYear = cal.get(Calendar.YEAR);
StringBuilder sb = new StringBuilder();
// 进行拼接
sb.append(NowYear).append("-").append(NowMonth).append("-").append(
MaxDay);
System.out.println(sb.toString());
return sb.toString();
}
/**
* 显示时间
* @param time
* @return
*/
public static String showTime(long time) {
long hour = time / (60 * 60 * 1000);
long minute = (time - hour * 60 * 60 * 1000) / (60 * 1000);
long second = (time - hour * 60 * 60 * 1000 - minute * 60 * 1000) / 1000;
if (second >= 60) {
second = second % 60;
minute += second / 60;
}
if (minute >= 60) {
minute = minute % 60;
hour += minute / 60;
}
String ok = hour + "小时" + minute + "分" + second + "秒";
return ok;
}
/**
* String 类型转换成java.util.Date类型
* @param string
* @return
* @throws Exception
*/
public static Date StringSwitchUDate(String string) throws Exception {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date time = sdf.parse(string);
return time;
}
/**
* 获取当前月的最后一天
*
* @return
*/
public static Date LastDay() {
Calendar cal = Calendar.getInstance();
// 把日期设置为当月第一天
cal.set(Calendar.DATE, 1);
// 日期回滚一天，也就是最后一天
cal.roll(Calendar.DATE, -1);

Date date=cal.getTime();
System.out.println("riqi:"+date);
return date;
}
/**
* 获取下个月一号
*
* @return
*/
public static Date CatchNextMonthDay() {
Calendar cal = Calendar.getInstance();
// 把日期设置为当月第一天
cal.set(Calendar.DATE, 1);
// 把月份设置成当前月的下一个月
cal.add(Calendar.MONTH, 1);

Date date = cal.getTime();
return date;
}
/**
* 获取当前日期31天后的日期
*
* @return
*/
public static Date CatchNext31Day(Date date) {
Calendar cal = Calendar.getInstance();
cal.setTime(date);
cal.roll(Calendar.MONTH, 1);
cal.roll(Calendar.DATE, 1);
Date newdate = cal.getTime();
return newdate;
}
}