/**
* 获取当前时间的时间戳
* @return
*/
public static String getTimeInMillis() {
long timeInMillis = Calendar.getInstance().getTimeInMillis();
return timeInMillis+"";
}
/**
* 获取位数为7位的随机数
* @return
*/
public static String getRandom() {
Random random = new Random();
int nextInt = random.nextInt(10000000);
nextInt=nextInt+1000000;
String str=nextInt+"";
return str;
}

public static String getTimeYearMonthDay() {
Calendar c = Calendar.getInstance();
int year=c.get(Calendar.YEAR);
int month=c.get(Calendar.MONTH)+1;
int day=c.get(Calendar.DAY_OF_MONTH);
int hh=c.get(Calendar.HOUR_OF_DAY);
int mi=c.get(Calendar.MINUTE);
int ss=c.get(Calendar.SECOND);
System.out.println(year+" "+month+" "+day+" "+hh+" "+mi+" "+ss);
return null;
}

/**
* 输入日期格式，返回格式内的内容，输入格式以-分隔
* @param dateFormat
* @return
*/
public static String getTimeYearMonthDay(String dateFormat) {
String[] strNow = new SimpleDateFormat(dateFormat).format(new Date()).toString().split("-");
String str="";
for (String string : strNow) {
str=str+string;
}
return str;
}
/**
* 获得20位的主键值，主键值的格式是13位的当前时间戳加7位的随机数
* @return
*/
public static String getPrimaryKey() {
return getTimeInMillis()+getRandom();
}
public static void main(String[] args) {
getTimeYearMonthDay("yyyy-MM-dd");
getTimeYearMonthDay();
System.out.println(getTimeInMillis());
System.out.println(getRandom());
System.out.println(getPrimaryKey());
}