//
//  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。

转载请标明出处：http://www.cnblogs.com/anxin1225/p/3660506.html

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