package com.dy.pipIrrWebFile.fm;
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import java.util.Calendar;
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public class FileNameIdUtil {
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private static int add = 0 ;
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private static int chengShu = 1000 ;
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private static int maxAdd = 999 ;
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private static long last = 0 ;
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//后缀
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private static String suffix = "0" ;
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static {
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last = current() ;
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}
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/**
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* 为自实现程序提供的ID生成器
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* 15长度ID，年度取两位，如果是17位长度ID，年度取四位，那17位数字超出了javascript的表数范围
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*/
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public String generate(){
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return doGenerate() ;
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}
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/**
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* 设置后缀，不同子系统设置不同的后缀
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* @param suffix
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*/
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public static void setSuffix(String suffix)throws Exception{
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if(suffix == null || suffix.trim().equals("")){
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throw new Exception("后缀不能为空") ;
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}
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FileNameIdUtil.suffix = suffix.trim() ;
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}
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/**
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* 执行生成
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* @return
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*/
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private synchronized String doGenerate(){
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Long id = null ;
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long now = current() ;
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if(now != last){
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//上次生成ID 与本次生成ID 不在同一秒内
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last = now ;
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add = 0 ;
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id = last * chengShu + add ++;
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}else{
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//上次生成ID 与本次生成ID 在同一秒内
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if(add == maxAdd){
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//附加量已经用尽
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waitNextSecond(last) ;//等到下一秒
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id = last * chengShu + add ++ ;//返回上一秒生成的ID
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add = 0 ;//附加量归零，为下一秒准备
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}else{
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//附加量未用尽
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id = last * chengShu + add ++ ;
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}
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}
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return id + suffix ;
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}
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/**
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* 等待下一秒到来
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* @param last
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*/
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private void waitNextSecond(Long last){
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try {
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Thread.sleep(10);
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} catch (InterruptedException e) {
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}finally{
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long now = current() ;
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if(now == last){
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waitNextSecond(last) ;
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}
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}
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}
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/**
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* 格式为 150516010203
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* @return
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*/
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private static long current(){
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Calendar cal = Calendar.getInstance();
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long d = (cal.get(Calendar.YEAR) % 100) * 10000000000L
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+ (cal.get(Calendar.MONTH) + 1) * 100000000L
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+ cal.get(Calendar.DAY_OF_MONTH) * 1000000L
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+ cal.get(Calendar.HOUR_OF_DAY) * 10000L
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+ cal.get(Calendar.MINUTE) * 100L
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+ cal.get(Calendar.SECOND) ;
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return d ;
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}
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public static void main(String args[]){
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FileNameIdUtil o = new FileNameIdUtil() ;
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int total = 800 ;
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long start = System.currentTimeMillis() ;
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for(int i = 0 ; i < total ; i++){
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System.out.println((String)(o.generate())) ;
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}
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long end = System.currentTimeMillis() ;
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System.out.println("产生" + total + "ID用时" + (end - start) + "毫秒");
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}
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}
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