您当前的位置： 首页 > 学无止境 > 心得笔记 网站首页心得笔记

〖第11章：Java常用类库〗_实例操作：取得当前日期

发布时间：2020-12-24 17:45:13编辑：雪饮阅读（）

 实现获取当前时间

设计一个类获取当前时间，输出格式分别有3种风格
“xxxx-xx-xx xx:xx:xx.xxxx”、”xxxx年xx月xx日 xx时xx分xx秒xxxx毫秒”、” xxxxxxxxxxxxxxxxxx”(伪时间戳)
用GregorianCalendar实现获取当前时间
import java.util.*;
class DateTime{
       private Calendar calendar=new GregorianCalendar();
       public String getDate(){
              //用StringBuffer类实现性能更好
              StringBuffer sbf=new StringBuffer();
              sbf.append(this.addZero(this.calendar.get(Calendar.YEAR),4)).append("-");
              sbf.append(this.addZero(this.calendar.get(Calendar.MONTH)+1,2)).append("-");
              sbf.append(this.addZero(this.calendar.get(Calendar.DAY_OF_MONTH),2)).append(" ");
              sbf.append(this.addZero(this.calendar.get(Calendar.HOUR_OF_DAY),2)).append(":");
              sbf.append(this.addZero(this.calendar.get(Calendar.MINUTE),2)).append(":");
              sbf.append(this.addZero(this.calendar.get(Calendar.SECOND),2)).append(".");
              sbf.append(this.addZero(this.calendar.get(Calendar.MILLISECOND),4));
              return sbf.toString() ;
       }
       public String getDateComplete(){
              StringBuffer sbf=new StringBuffer();
              sbf.append(this.addZero(this.calendar.get(Calendar.YEAR),4)).append("年");
              sbf.append(this.addZero(this.calendar.get(Calendar.MONTH)+1,2)).append("月");
              sbf.append(this.addZero(this.calendar.get(Calendar.DAY_OF_MONTH),2)).append(" ");
              sbf.append(this.addZero(this.calendar.get(Calendar.HOUR_OF_DAY),2)).append("时");
              sbf.append(this.addZero(this.calendar.get(Calendar.MINUTE),2)).append("分");
              sbf.append(this.addZero(this.calendar.get(Calendar.SECOND),2)).append("秒");
              sbf.append(this.addZero(this.calendar.get(Calendar.MILLISECOND),4)).append("毫秒");
              return sbf.toString() ;
       }
       //获取伪时间戳
       public String getTimeStamp(){
              StringBuffer sbf=new StringBuffer();
              sbf.append(this.addZero(this.calendar.get(Calendar.YEAR),4));
              sbf.append(this.addZero(this.calendar.get(Calendar.MONTH)+1,2));
              sbf.append(this.addZero(this.calendar.get(Calendar.DAY_OF_MONTH),2));
              sbf.append(this.addZero(this.calendar.get(Calendar.HOUR_OF_DAY),2));
              sbf.append(this.addZero(this.calendar.get(Calendar.MINUTE),2));
              sbf.append(this.addZero(this.calendar.get(Calendar.SECOND),2));
              sbf.append(this.addZero(this.calendar.get(Calendar.MILLISECOND),4));
              return sbf.toString() ;
       }
       private String addZero(int num,int len){
              StringBuffer sbf=new StringBuffer();
              sbf.append(num);
              while(sbf.length()<len){
                            sbf.insert(0,0);
              }
              return sbf.toString();
       }
}
public class Hello{
   public static void main(String args[]){
              System.out.println(new DateTime().getDate());
              System.out.println(new DateTime().getDateComplete());
              System.out.println(new DateTime().getTimeStamp());
   }
}
D:\>javac Hello.java
D:\>java Hello
2020-12-24 17:34:00.0394
2020年12月24 17时34分00秒0394毫秒
202012241734000395
实现虽然实现了，就是代码太多了，太麻烦。
用SimpleDateFormat实现获取当前时间
import java.util.*;
import java.text.* ;
class DateTime{
       public String getDate(){
              return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(new Date());
       }
       public String getDateComplete(){
              return new SimpleDateFormat("yyyy年MM月dd日 HH时mm分ss秒SSS毫秒").format(new Date());
       }
       //获取伪时间戳
       public String getTimeStamp(){
              return new SimpleDateFormat("yyyyMMddHHmmssSSS").format(new Date());
       }
}
public class Hello{
  public static void main(String args[]){
              System.out.println(new DateTime().getDate());
              System.out.println(new DateTime().getDateComplete());
              System.out.println(new DateTime().getTimeStamp());
   }
}

干的漂亮，要的就是这种极简风格。