////  IdGenerator.m//  Copyright (c) 2014年 青島拓宇網絡科技有限公司. All rights reserved.//#import "IdGenerator.h"static long long time_stamp = 0;static long long time_stamp_now = 0;static NSMutableArray *temp = NULL;static NSNumber *random_n = NULL;static NSLock *theLock = NULL;@implementation IdGenerator/* *  獲取下一個Id */+ (long long)next{        if(theLock == NULL)        theLock = [[NSLock alloc]init];        if(temp == NULL)        temp = [[NSMutableArray alloc]init];        @synchronized(theLock){        time_stamp_now = [[NSDate date] timeIntervalSince1970];        if(time_stamp_now != time_stamp){            //清空緩存，更新時間戳            [temp removeAllObjects];            time_stamp = time_stamp_now;        }                //判斷緩存中是否存在當前隨機數        while ([temp containsObject:(random_n = [NSNumber numberWithLong:arc4random() % 8999 + 1000])])            ;                if ([temp containsObject:random_n]) {            return -1;        }                [temp addObject:[NSNumber numberWithLong:[random_n longValue]]];    }        return (time_stamp * 10000) + [random_n longValue];}@end