IOS ID生成器

//
//  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

不重復的Id生成器，理論上每秒鍾最多可以生成8999條Id，實際上每秒鍾約能生成6000條Id。

轉載請標明出處：http://www.cnblogs.com/anxin1225/p/3660506.html

友情鏈接地址：http://c.jinhusns.com/