Java中获取时间戳的三种方式对比实现

System.currentTimeMillis()

public Date() {
  this(System.currentTimeMillis());
}

import java.util.Calendar; 
import java.util.Date; 
 
public class TimeTest { 
  private static long _TEN_THOUSAND=10000; 
  public static void main(String[] args) { 
    long times=1000*_TEN_THOUSAND; 
    long t1=System.currentTimeMillis(); 
    testSystem(times); 
    long t2=System.currentTimeMillis(); 
    System.out.println(t2-t1); 
    testCalander(times); 
    long t3=System.currentTimeMillis(); 
    System.out.println(t3-t2); 
    testDate(times); 
    long t4=System.currentTimeMillis(); 
    System.out.println(t4-t3); 
  } 
   
  public static void testSystem(long times){//use 188 
    for(int i=0;i<times;i++){ 
      long currentTime=System.currentTimeMillis(); 
    } 
  } 
 
  public static void testCalander(long times){//use 6299 
    for(int i=0;i<times;i++){ 
      long currentTime=Calendar.getInstance().getTimeInMillis(); 
    } 
  } 
   
  public static void testDate(long times){ 
    for(int i=0;i<times;i++){ 
      long currentTime=new Date().getTime(); 
    } 
     
  }  
}