设计模式之单例模式

来源：互联网发布：安广网络电视黑屏编辑：程序博客网时间：2024/06/06 03:27

单例模式，就是这个类在整个应用中只有一份内存，不能通过new来创造实例类。好处就是可以减少系统内存的消耗和减少系统构造和析构的时间，提高程序效率。

我们很多应用都有个日期类，来显示当前的年，月，日等，特别是用于时钟的应用设计，每次更新时间都new一下，系统的开销是很大的，这里采用单例模式来设计，就能很好的解决这个问题，附上代码如下，开发平台为android平台：

package com.android.DigitalTime;

import java.util.Calendar;
import android.content.Context;
import android.util.Log;

public class DateInfo
{
   private static int date_month;
   private static int date_day;
   private static int date_hour;
   private static int date_minute;
   private static int date_second;
   private static int date_week;
   private static DateInfo dateInfo=null;
   private static boolean IsDebug = false;
   private static String TAG = "DateInfo";
   public int getDate_month()
   {
       return date_month;
   }
   public void setDate_month(int dateMonth)
   {
       date_month = dateMonth;
   }
   public int getDate_day() {
       return date_day;
   }
   public void setDate_day(int dateDay)
   {
       date_day = dateDay;
   }
   public int getDate_hour()
   {
       return date_hour;
   }
   public void setDate_hour(int dateHour)
   {
       date_hour = dateHour;
   }
   public int getDate_minute()
   {
       return date_minute;
   }
   public void setDate_minute(int dateMinute)
   {
       date_minute = dateMinute;
   }
   public int getDate_second() {
       return date_second;
   }
   public void setDate_second(int dateSecond)
   {
       date_second = dateSecond;
   }
   public int getDate_week() {
       return date_week;
   }
   public void setDate_week(int dateWeek)
   {
       date_week = dateWeek;
   }

   private DateInfo(int dateMonth, int dateDay, int dateHour, int dateMinute,
           int dateSecond, int dateWeek)
   {
       super();
       date_month = dateMonth;
       date_day = dateDay;
       date_hour = dateHour;
       date_minute = dateMinute;
       date_second = dateSecond;
       date_week = dateWeek;
   }
   private DateInfo()
   {
       super();
       // TODO Auto-generated constructor stub
   }

   public static DateInfo getInstance(Context context)
   {
       if(dateInfo==null)
       {
           dateInfo = new DateInfo();
       }
       try
       {
            Calendar calendar = Calendar.getInstance();
            // calendar.setTimeInMillis(SystemClock.uptimeMillis());
            dateInfo.setDate_month(calendar.get(Calendar.MONTH) + 1);
            dateInfo.setDate_day(calendar.get(Calendar.DAY_OF_MONTH));
            dateInfo.setDate_week(calendar.get(Calendar.DAY_OF_WEEK));
            if (android.text.format.DateFormat.is24HourFormat(context))
            {
                dateInfo.setDate_hour(calendar.get(Calendar.HOUR_OF_DAY));
            }
            else
            {
                dateInfo.setDate_hour(calendar.get(Calendar.HOUR));
                if (calendar.get(Calendar.HOUR)==0)
                {
                   dateInfo.setDate_hour(calendar.get(Calendar.HOUR)+12);
                }
            }

            dateInfo.setDate_minute(calendar.get(Calendar.MINUTE));
            //Log.i("dingchao Digital Time", "dateInfo.getDate_minute():"+dateInfo.getDate_minute());
            dateInfo.setDate_second(calendar.get(Calendar.SECOND));

       }
       catch (Exception e)
       {
            // TODO Auto-generated catch block
            e.printStackTrace();
       }
       return dateInfo;
   }

}