java日期转化

package com.kang.util;

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

public class CalendarTest {
	public static void main(String[] args) throws ParseException {
		// 获取当前年份、月份、日期
		Calendar cale = null;
		cale = Calendar.getInstance();
		int year = cale.get(Calendar.YEAR);
		int month = cale.get(Calendar.MONTH) + 1;
		int day = cale.get(Calendar.DATE);
		int hour = cale.get(Calendar.HOUR_OF_DAY);
		int minute = cale.get(Calendar.MINUTE);
		int second = cale.get(Calendar.SECOND);
		int dow = cale.get(Calendar.DAY_OF_WEEK);
		int dom = cale.get(Calendar.DAY_OF_MONTH);
		int doy = cale.get(Calendar.DAY_OF_YEAR);

		System.out.println("Current Date: " + cale.getTime());
		System.out.println("Year: " + year);
		System.out.println("Month: " + month);
		System.out.println("Day: " + day);
		System.out.println("Hour: " + hour);
		System.out.println("Minute: " + minute);
		System.out.println("Second: " + second);
		System.out.println("Day of Week: " + dow);
		System.out.println("Day of Month: " + dom);
		System.out.println("Day of Year: " + doy);

		// 获取当月第一天和最后一天
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
		String firstday, lastday;
		// 获取前月的第一天
		cale = Calendar.getInstance();
		cale.add(Calendar.MONTH, 0);
		cale.set(Calendar.DAY_OF_MONTH, 1);
		firstday = format.format(cale.getTime());
		// 获取前月的最后一天
		cale = Calendar.getInstance();
		cale.add(Calendar.MONTH, 1);
		cale.set(Calendar.DAY_OF_MONTH, 0);
		lastday = format.format(cale.getTime());
		System.out.println("本月第一天和最后一天分别是 ： " + firstday + " and " + lastday);

		// 获取当前日期字符串
		Date d = new Date();
		System.out.println("当前日期字符串1：" + format.format(d));
		System.out.println("当前日期字符串2：" + year + "/" + month + "/" + day + " "
				+ hour + ":" + minute + ":" + second);

		// 字符串格式转化，获取年份月份或其他
		String ss = "2014-08";
		Calendar Date = Calendar.getInstance();
		SimpleDateFormat simpleDate = new SimpleDateFormat("yyyy-MM"); // yyyy-MM-dd
																		// hh:mm:ss
		Date.setTime(simpleDate.parse(ss));// Date和以上的Cale的使用方法相同
		int days = Date.getActualMaximum(Calendar.DAY_OF_MONTH);	// 获取当前月的天数
		int month1 = Date.get(Calendar.MONTH);	// 获取当前月的天数

		// 获取前一天、前一个月的日期
		Calendar calendar = Calendar.getInstance();// 此时打印它获取的是系统当前时间
		calendar.add(Calendar.DATE, -1); // 得到前一天
		String yestedayDate = new SimpleDateFormat("yyyy-MM-dd")
				.format(calendar.getTime());

		calendar.add(Calendar.MONTH, -1); // 得到前一个月
		int year2 = calendar.get(Calendar.YEAR);
		int month2 = calendar.get(Calendar.MONTH) + 1; // 输出前一月的时候要记得加1

	}

}