java操作时间日期类

有时候，我们需要把一个特定的字符串转成日期类型，有时候又要把日期类型转成字符串格式。还有有时候要实现日期转星期的需求。又或者需要获得某个日期的下一天的日期。在这里大都可以通过以下类来实现。如下：

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

public class DayDate {
	/** 星期几 */
	private String day;

	/** 日期 */
	private String date;

	final String dayNames[] = { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" };

	public DayDate() {
		super();
		DateFormat objDateFormat = new SimpleDateFormat("yyyy-MM-dd");
		Calendar objCalendar = Calendar.getInstance();
		this.date = objDateFormat
				.format(new Date(objCalendar.getTimeInMillis()+24L*60L*60L*1000L));

		int dayOfWeek = objCalendar.get(Calendar.DAY_OF_WEEK);
		this.day = dayNames[dayOfWeek - 1];
	}
	/**
	 * 取得下一天
	 */
	public String nextDay(){
		Calendar objCalendar = Calendar.getInstance();
		objCalendar.setTime(Date.valueOf(this.date));
		int dayOfWeek = objCalendar.get(Calendar.DAY_OF_WEEK)+1>7 ? 1:objCalendar.get(Calendar.DAY_OF_WEEK)+1;
		return this.day = dayNames[dayOfWeek - 1];
	}
	/**
	 * 取得下一date
	 * @return
	 */
	public String nextDate(){
		DateFormat objDateFormat = new SimpleDateFormat("yyyy-MM-dd");
		Calendar objCalendar = Calendar.getInstance();
		objCalendar.setTime(Date.valueOf(this.date));
		return this.date = objDateFormat
		.format(new Date(objCalendar.getTimeInMillis()+24L*60L*60L*1000L));

	}
	/**
	 * 构造函数，以字段初始化
	 *
	 * @param day
	 *            设置星期几
	 * @param date
	 *            设置日期
	 */
	public DayDate(String date) {
		super();
		Calendar objCalendar = Calendar.getInstance();
		objCalendar.setTime(Date.valueOf(date));
		int dayOfWeek = objCalendar.get(Calendar.DAY_OF_WEEK);
		this.day = dayNames[dayOfWeek - 1];
		this.date = date;
	}

	/**
	 * @return the date
	 */
	public String getDate() {
		return date;
	}

	/**
	 * @param date
	 *            the date to set
	 */
	public void setDate(String date) {
		this.date = date;
	}

	/**
	 * @return the day
	 */
	public String getDay() {
		return day;
	}

	/**
	 * @param day
	 *            the day to set
	 */
	public void setDay(String day) {
		this.day = day;
	}

	public String toString() {
		return day + "(" + date + ")";
	}
	public static void main(String[] args){
		System.out.println(new DayDate("2010-07-30").nextDate());
	}
}