IOS ID生成器

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// //  IdGenerator.m //  Copyright (c) 2014年 青岛拓宇网络科技有限公司. 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   /*  *  获取下一个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){             //清空缓存，更新时间戳             [temp removeAllObjects];             time_stamp = time_stamp_now;         }                   //判断缓存中是否存在当前随机数         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

不重复的Id生成器，理论上每秒钟最多可以生成8999条Id，实际上每秒钟约能生成6000条Id。

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