.Net3月份开发札记

筛选数据

需求：如果数据库中存在OrderNum相同，且IsDefault不同的记录，那么IsDefault值为0的记录将替换值为1的记录（IsDefault值为1的记录不展示）。

由于查出来的数据不多，100条以内，所以我是直接全部查询到List内存中，然后再内存中进行数据过滤的操作，思来想去都觉得我如下的实现方式很low，但是我一时又没想到好的办法，不知道大家有没有好的办法？

            var newList = list.ToList();
            //筛选出哪些排序号有重复
            var orderNumList = newList.GroupBy(g => g.OrderNum).Select(g => new { orderNum = g.Key, count = g.Count() }).Where(g => g.count > 1).Select(s => s.orderNum).ToList();
            var cfList = newList.Where(w => orderNumList.Contains(w.OrderNum)); //获取有重复排序号的记录

            var cfDefaultList = cfList.Where(w => w.IsDefault);  //默认模块记录
            var cfNoDefaultList = cfList.Where(w => w.IsDefault == false); //非默认模块记录

            var intersectedList = from d in cfDefaultList join f in cfNoDefaultList on d.OrderNum equals f.OrderNum where d.IsDefault!= f.IsDefault select d;

            var newIntersectedList = intersectedList.Distinct().ToArray(); //排序号相同，既存在默认记录也存在非默认记录的数据 

                if (newIntersectedList != null && newIntersectedList.Length > 0)
                {
                    for (int i = 0; i < newIntersectedList.Length; i++)
                    {
                        if (newList.Contains(newIntersectedList[i]))
                        {
                            newList.Remove(newIntersectedList[i]);
                        }
                    }
                }
           newList = newList.OrderBy(x => x.OrderNum).ToList();

以上的newList就代码截图中的数据。

优化API接口

有一个API接口经常卡顿，而且很不稳定，快的时候2~3秒，慢的时候10秒去了。

接口需求：根据社区ID获取优惠券记录。

分析：

  • 负责给API接口提供数据的系统中，缺少许多索引，存在许多慢查询视图。
  • 原来的LINQ实现方式是在内存中分页，响应速度太慢。
  • 并发请求的情况下，资源占用。

优化思路：

1、使用缓存

同一个社区的人在同一时间所看到的优惠券记录应该是一样的，而且我们应该允许脏读，我们在12306上面买火车票的时候，经常也会看到显示有票，但是下单又没有了，可能是使用了缓存，那么我们这里其实同样的可以采用缓存来缓解并发问题。

在WebAPI上面加缓存，那么又分为客户端缓存和服务器缓存。而我们知道，在ASP.NET WebForm和ASP.NET MVC中都是有页面输出缓存的，而在WebAPI中默认没有，从NuGet上面下载WebApi.OutputCache.V2，然后再API接口上添加

[CacheOutput(ClientTimeSpan = 5)]//, ServerTimeSpan = 5

我这里没法直接使用服务器输出缓存，那是因为无法捕获缓存变量参数。因为我们API接口的请求参数是string appParam，字符串类型的，它是一个json对象进过base64位编码，然后再进过url编码生成的字符串。

我们只能解析后，获取社区ID，然后根据社区ID来设置缓存，把社区ID+ pageIndex就作为缓存的Key，考虑到需要缓存的数据量很小，这里我直接使用.NET自带的缓存，引入命名空间：System.Web.Caching;

      private static System.Web.Caching.Cache ObjCache = HttpRuntime.Cache;
        /// <summary>
        /// 设置当前指定Key的Cache值,并限定过期时间
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="TimeOuts">超时时间（秒）</param>
        public static void SetCacheSeconds(string Key, object Obj, double TimeOuts)
        {
            ObjCache.Insert(Key, Obj, null, System.DateTime.Now.AddSeconds(TimeOuts), TimeSpan.Zero);
        }
        /// <summary>
        /// 获取当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <returns>缓存的值</returns>
        public static object GetCache(string Key)
        {
            return ObjCache[Key];
        }

缓存操作类Cache完整代码如下：

/*==================================
 * Author:
 * CreateTime：2014-7-15 17:26:29
 * Description：Cache操作类
 ===================================*/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.Caching;
using System.Runtime.CompilerServices;
using System.Web;
using System.Security.Policy;

namespace SSY.Util
{
    /// <summary>
    /// 缓存处理相关类
    /// </summary>
    public class Cache
    {
        private static System.Web.Caching.Cache ObjCache = HttpRuntime.Cache;
        private static short TimeOut = 720;

        #region 清除指定键值的缓存
        /// <summary>
        /// 清除指定键值的缓存
        /// </summary>
        /// <param name="Key">要清除的缓存的key值</param>
        public static void Clear(string Key)
        {
            if (ObjCache[Key] != null)
            {
                ObjCache.Remove(Key);
            }
        }
        #endregion

        #region 返回系统中缓存的个数
        /// <summary>
        /// 返回系统中缓存的个数
        /// </summary>
        /// <returns>缓存个数</returns>
        public static int Count()
        {
            return ObjCache.Count;
        }
        #endregion

        #region 获取当前指定Key的Cache值
        /// <summary>
        /// 获取当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <returns>缓存的值</returns>
        public static object GetCache(string Key)
        {
            return ObjCache[Key];
        }
        #endregion

        #region 设置当前指定Key的Cache值
        /// <summary>
        /// 设置当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        public static void SetCache(string Key, object Obj)
        {
            ObjCache.Insert(Key, Obj);
        }
        #endregion

        #region 设置当前指定Key的Cache值,并限定过期时间
        /// <summary>
        /// 设置当前指定Key的Cache值,并限定过期时间
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="TimeOuts">超时时间（分钟）</param>
        public static void SetCache(string Key, object Obj, int TimeOuts)
        {
            ObjCache.Insert(Key, Obj, null, System.DateTime.Now.AddMinutes((double)TimeOuts), TimeSpan.Zero);
        }
        /// <summary>
        /// 设置当前指定Key的Cache值,并限定过期时间
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="TimeOuts">超时时间（秒）</param>
        public static void SetCacheSeconds(string Key, object Obj, double TimeOuts)
        {
            ObjCache.Insert(Key, Obj, null, System.DateTime.Now.AddSeconds(TimeOuts), TimeSpan.Zero);
        }
        #endregion

        #region 设置当前指定Key的Cache值,依赖文件过期
        /// <summary>
        /// 设置当前指定Key的Cache值,依赖文件过期
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="Files">相对地址，例如"~/files.xml"</param>
        public static void SetCache(string Key, object Obj, string Files)
        {
            CacheDependency cacheDep = new CacheDependency(System.Web.HttpContext.Current.Server.MapPath(Files),System.DateTime.Now);
            SetCache(Key, Obj, TimeOut, cacheDep, CacheItemPriority.High);
        }
        #endregion

        #region 设置当前指定Key的Cache值
        /// <summary>
        /// 设置当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="Priority">撤销缓存的优先值，此参数的值取自枚举变量“CacheItemPriority”，优先级低的数据项将先被删除。此参数主要用在缓存退出对象时.</param>
        public static void SetCache(string Key, object Obj, CacheItemPriority Priority)
        {
            SetCache(Key, Obj, TimeOut, null, Priority);
        }
        #endregion

        #region 设置当前指定Key的Cache值
        /// <summary>
        /// 设置当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="TimeOuts">一个TimeSpan，表示缓存参数将在多长时间以后被删除</param>
        /// <param name="CacheDep">缓存的依赖项,需要一个CacheDependency，可初始化一个</param>
        /// <param name="Priority">撤销缓存的优先值，此参数的值取自枚举变量“CacheItemPriority”，优先级低的数据项将先被删除。此参数主要用在缓存退出对象时</param>
        public static void SetCache(string Key, object Obj, int TimeOuts, CacheDependency CacheDep, CacheItemPriority Priority)
        {
            ObjCache.Insert(Key, Obj, CacheDep, System.DateTime.MaxValue, TimeSpan.FromHours((double)TimeOuts), Priority, null);
        }
        #endregion
    }
}

修改API接口代码：

           #region added by zouqj 2017-3-7
           var result = Util.Cache.GetCache(CommunityID+ pageIndex) as Result<List<GetAvailableCouponsModel>>;
           if (result==null) //不存在则写入缓存
           {
               //组装参数
               Dictionary<string, string> inParams = new Dictionary<string, string>();
               inParams.Add("UserId", userId);
               inParams.Add("PageIndex", pageIndex);
               inParams.Add("PageSize", pageSize);
               inParams.Add("CommunityID", CommunityID+ pageIndex);               ...
               RequestParam RequestParam = GetRequestParam(methodName, inParams, AuthenticationId);
               var jsonContent = JsonConvert.SerializeObject(RequestParam);
               result = DoPost<List<GetAvailableCouponsModel>>(jsonContent, PostUrl);

               Util.Cache.SetCacheSeconds(CommunityID, result, 10); //写入缓存
           }
           return result;

2、改为存储过程实现

因为这个接口的业务逻辑比较复杂，之前的Linq代码写了好长一大串，获取的记录数很多，而且还是在内存中进行分页实现，所以我将原来的LINQ实现代码修改为分页存储过程实现。

存储过程代码如下：

------------------------------------------创建领券中心存储过程 created by zouqj-2017-3-1-----------------------------------
IF EXISTS(Select Name From Sysobjects Where Name=‘usp_GetAvailableCoupons‘ And Xtype=‘P‘)
DROP PROCEDURE usp_GetAvailableCoupons
GO
CREATE PROC usp_GetAvailableCouponsl
(
@PageIndex int, --页码
@PageSize int, --每页容纳的记录数
@Sort NVARCHAR(50), --排序字段及规则,不用加order by
@hostName nvarchar(100),--服务器地址
@CommunityID UNIQUEIDENTIFIER, --社区
@IsGetCount BIT --是否得到记录总数，1为得到记录总数，0为不得到记录总数，返回记录集
)
AS
-------------------------------定义变量-----------------------
declare @strSql NVARCHAR(max);
DECLARE  @dt datetime2(7) --查询时间
SET @dt=GETDATE();
set nocount on;
----------------------------------------SQL开始--------------------------------------------无分类
IF @IsGetCount=1
BEGIN

SET @strSql=N‘SELECT COUNT(*) FROM (SELECT DISTINCT t.CampaignID from
(SELECT
c.ID AS CampaignID
 FROM MK_Campaign c WITH ( NOLOCK ) INNER JOIN MK_CouponConfig f WITH ( NOLOCK ) ON c.ID=f.CampaignID
           INNER JOIN MK_Coupon p WITH ( NOLOCK ) ON f.CouponID=p.ID
           WHERE f.CouponGetType=2 AND f.ReceiveStartTime <[email protected] AND f.ReceiveEndTime>= @dt
           AND c.State=4 --执行中
           AND p.WholeNetwork=1 --全网优惠
UNION ALL
SELECT
    a.[ID] AS CampaignID
    FROM  [dbo].[MK_Campaign] AS a WITH ( NOLOCK )
        INNER JOIN [dbo].[MK_CouponConfig] AS b  WITH ( NOLOCK ) ON a.[ID] = b.[CampaignID]
        AND (b.[ReceiveStartTime] <= @dt) AND (b.[ReceiveEndTime] >= @dt) AND (2 = b.[CouponGetType]) AND (4 = a.[State])
        INNER JOIN [dbo].[MK_Coupon] AS c WITH ( NOLOCK ) ON b.[CouponID] = c.[ID]
        INNER JOIN [dbo].[MK_CouponRestriction] AS d  WITH ( NOLOCK ) ON c.[ID] = d.[CompainID]
        LEFT OUTER JOIN [dbo].[MK_CouponRestrictCategory] AS e WITH ( NOLOCK ) ON d.[ID] = e.[CouponRestrictionID]
        LEFT OUTER JOIN [dbo].[MK_CouponRestrictionOrg] AS f WITH ( NOLOCK ) ON d.[ID] = f.[CouponRestrictionID]
        INNER JOIN [dbo].[ViewOrganizationCommunityForInterface] AS v ON f.[OrgID] = v.[ID]
    where [email protected]  and 1 = d.[Type]
UNION ALL
SELECT
   a.ID AS CampaignID
   FROM MK_Campaign a  WITH ( NOLOCK )
             INNER JOIN MK_CouponConfig b WITH ( NOLOCK ) ON a.ID=b.CampaignID AND (b.[ReceiveStartTime] <= @dt) AND (b.[ReceiveEndTime] >[email protected])
             INNER JOIN [dbo].[MK_Coupon] AS c WITH ( NOLOCK ) ON b.[CouponID] = c.[ID] and (2 = b.[CouponGetType]) AND (4 = a.[State])
             INNER JOIN [dbo].[MK_CouponRestriction] AS d WITH ( NOLOCK ) ON c.[ID] = d.[CompainID]  AND (2 = d.[Type])
             LEFT OUTER JOIN MK_CouponRestrictionProduct AS e WITH ( NOLOCK ) ON d.[ID] = e.[CouponRestrictionID]
             LEFT OUTER JOIN SL_Product AS f WITH ( NOLOCK ) ON (e.ProductID = f.ID)
             INNER JOIN ViewOrganizationCommunityForInterface v ON v.ID=f.PublisherID
   where [email protected]
   ) t
 ) AS tt‘
----------------------------------------------------------------------------------
END
ELSE
BEGIN
SET @strSql=N‘SELECT DISTINCT t.* from(
SELECT
          c.ID AS CampaignID,
          c.Name AS CampaignName,
          f.ValidityStartTime AS CampaignStartTime,
          f.ValidityEndTime AS CampaignEndTime,
          p.Name AS CouponsName,
          p.Price AS CouponsAmount,
          (CASE WHEN p.IsLimited =1 THEN 1 ELSE 2 END) AS IsLimited,
          p.FullAmount AS MinAmount,
          f.ValidityEndTime AS CouponsEndTime,
          f.ValidityStartTime AS CouponsStartTime,
          (CASE WHEN f.IsRepeateGet =1 THEN 1 ELSE 2 END) AS IsCanRepeatedReceive,
          f.ReceiveAddress AS ReceiveAddress,
          f.ReceiveEndTime AS ReceiveEndTime,
          f.ReceiveStartTime AS ReceiveStartTime,
          f.ReceiveMode AS ReceiveMethod,
          f.ProvideNum AS ReceiveNum,
          p.CreateTime AS CreateTime,
          p.Price AS Price,
          f.RemainCouponNum AS RemainCouponNum,
          f.ID AS CouponConfigId,
          p.WholeNetwork AS CouponsType,
          (CASE WHEN f.IconUrl IS NULL THEN N‘‘‘‘ WHEN f.IconUrl=N‘‘‘‘ THEN N‘‘‘‘ ELSE @hostName+f.IconUrl END) AS IconUrl
FROM MK_Campaign c WITH ( NOLOCK )
                 INNER JOIN MK_CouponConfig f WITH ( NOLOCK ) ON c.ID=f.CampaignID
                 INNER JOIN MK_Coupon p WITH ( NOLOCK ) ON f.CouponID=p.ID
          WHERE f.CouponGetType=2 AND f.ReceiveStartTime <= @dt AND f.ReceiveEndTime>= @dt AND c.State=4 AND p.WholeNetwork=1 --全网优惠
--
UNION ALL
          SELECT a.[ID] AS CampaignID,
          a.[Name] AS CampaignName,
          b.[ValidityStartTime] AS CampaignStartTime,
          b.[ValidityEndTime] AS CampaignEndTime,
          c.[Name] AS CouponsName,
          c.[Price] AS CouponsAmount,
          CASE WHEN (c.[IsLimited] = 1) THEN 1 ELSE 2 END AS IsLimited,
          c.[FullAmount] AS MinAmount,
          b.[ValidityEndTime] AS CouponsEndTime,
          b.[ValidityStartTime] AS CouponsStartTime,
          CASE WHEN (b.[IsRepeateGet] = 1) THEN 1 ELSE 2 END AS IsCanRepeatedReceive,
          b.[ReceiveAddress] AS [ReceiveAddress],
          b.[ReceiveEndTime] AS [ReceiveEndTime],
          b.[ReceiveStartTime] AS [ReceiveStartTime],
          b.[ReceiveMode] AS ReceiveMethod,
          b.[ProvideNum] AS ReceiveNum,
          c.[CreateTime] AS CreateTime,
          c.[Price] AS Price,
          b.[RemainCouponNum] AS RemainCouponNum,
          b.[ID] AS CouponConfigId,
          e.[Type] AS CouponsType,
          CASE WHEN (b.[IconUrl] = N‘‘‘‘ OR b.[IconUrl] IS NULL) THEN N‘‘‘‘ ELSE @hostName+b.[IconUrl] END AS IconUrl
                    FROM  [dbo].[MK_Campaign] AS a WITH ( NOLOCK )
                        INNER JOIN [dbo].[MK_CouponConfig] AS b  WITH ( NOLOCK ) ON a.[ID] = b.[CampaignID] AND (b.[ReceiveStartTime] <= @dt) AND (b.[ReceiveEndTime] >= @dt) AND (2 = b.[CouponGetType]) AND (4 = a.[State])
                        INNER JOIN [dbo].[MK_Coupon] AS c WITH ( NOLOCK ) ON b.[CouponID] = c.[ID]
                        INNER JOIN [dbo].[MK_CouponRestriction] AS d  WITH ( NOLOCK ) ON c.[ID] = d.[CompainID]
                        LEFT OUTER JOIN [dbo].[MK_CouponRestrictCategory] AS e WITH ( NOLOCK ) ON d.[ID] = e.[CouponRestrictionID]
                        LEFT OUTER JOIN [dbo].[MK_CouponRestrictionOrg] AS f WITH ( NOLOCK ) ON d.[ID] = f.[CouponRestrictionID]
                        INNER JOIN [dbo].[ViewOrganizationCommunityForInterface] AS v ON f.[OrgID] = v.[ID]
                    where [email protected]  and 1 = d.[Type]
UNION ALL
SELECT
       a.ID AS CampaignID,
       a.Name AS CampaignName,
       b.ValidityStartTime AS CampaignStartTime,
       b.ValidityEndTime AS CampaignEndTime,
       c.Name AS CouponsName,
       c.Price AS CouponsAmount,
       (CASE WHEN c.IsLimited=1 then 1 else 2 END) AS IsLimited,
       c.FullAmount AS MinAmount,
       b.ValidityEndTime AS CouponsEndTime,
       b.ValidityStartTime AS CouponsStartTime,
       (case when b.IsRepeateGet=1 then 1 else 2 END) AS IsCanRepeatedReceive,
       b.ReceiveAddress AS ReceiveAddress,
       b.ReceiveEndTime AS ReceiveEndTime,
       b.ReceiveStartTime AS ReceiveStartTime,
       b.ReceiveMode AS ReceiveMethod,
       b.ProvideNum AS ReceiveNum,
       c.CreateTime AS CreateTime,
       c.Price AS Price,
       b.RemainCouponNum AS RemainCouponNum,
       b.ID AS CouponConfigId,
       d.[TYPE] AS CouponsType,
       (CASE WHEN b.IconUrl IS NULL THEN N‘‘‘‘ WHEN b.IconUrl=N‘‘‘‘ THEN N‘‘‘‘ ELSE @hostName+b.IconUrl END) AS IconUrl
   FROM MK_Campaign a  WITH ( NOLOCK )
                    INNER JOIN MK_CouponConfig b WITH ( NOLOCK ) ON a.ID=b.CampaignID AND (b.[ReceiveStartTime] <= @dt) AND (b.[ReceiveEndTime] >= @dt)
                    INNER JOIN [dbo].[MK_Coupon] AS c WITH ( NOLOCK ) ON b.[CouponID] = c.[ID] and (2 = b.[CouponGetType]) AND (4 = a.[State])
                    INNER JOIN [dbo].[MK_CouponRestriction] AS d WITH ( NOLOCK ) ON c.[ID] = d.[CompainID]  AND (2 = d.[Type])
                    LEFT OUTER JOIN MK_CouponRestrictionProduct AS e WITH ( NOLOCK ) ON d.[ID] = e.[CouponRestrictionID]
                    LEFT OUTER JOIN SL_Product AS f WITH ( NOLOCK ) ON (e.ProductID = f.ID)
                    INNER JOIN ViewOrganizationCommunityForInterface v ON v.ID=f.PublisherID
                    where [email protected]
   ) t
ORDER BY [email protected]
offset (@PageIndex-1)*@PageSize ROWS  FETCH NEXT @PageIndex*@PageSize ROWS ONLY‘
end
--执行SQL
exec sp_executesql @strSql,N‘@PageIndex int,@PageSize int,@Sort nvarchar(50),@hostName nvarchar(100),@CommunityID UNIQUEIDENTIFIER,@IsGetCount bit,@dt datetime2(7)‘,@PageIndex =@PageIndex,@PageSize =@PageSize,@Sort=@Sort,@hostName=@hostName,@CommunityID=@CommunityID,@IsGetCount=@IsGetCount,@dt=@dt
set nocount off;

这里需要注意的是，存储执行是，先关闭计数，set nocount on;，然后再打开set nocount off;，这样可以提升性能。还有就是使用WITH ( NOLOCK )允许脏读，提升查询效率。

这里遇到一个很诡异的问题，我使用exec sp_executesql @strSql,N‘....‘的方式来执行是没有问题的，而如果我使用拼接sql的方式，会报错，因为sql字符串被截断了，只截取到了4000个字符长度，即便我把字符串变量长度设置为nvarchar(max)也没用。

分页方式采用Sqlserver2012以上版本才支持的高效方式：offset ... FETCH NEXT ...ROWS ONLY

原来Linq的执行时间测试：

我修改为存储过程之后的执行时间测试：

性能差距非常明显。

时间： 2024-11-05 11:36:05

.Net3月份开发札记的相关文章

我们都是IT民工---------流浪人IDE开发札记

你生命中的有些东西终究会失去,比如我住了6年的陈寨,这个聚集了郑州十几万IT民工的地方,说拆就拆了.再比如我玩了3年的坦克英雄,这个带给我太多快乐的游戏,说停就停了. 编程对我而言是种爱好,我上学6年,工作14年,期间学会了二十多种编程语言,新潮如go和swift,生冷如F#和lisp,我都学过,至于热门的,编程语言排行榜上前14位的语言,我都会用.也许你觉得我是在吹牛,那就让我从头说起吧.     我上中学时开始学习编程,那时候没见过什么电脑,看书上说电脑是由主机显示器和硬盘驱动器组成的,我想

6月份开发问题整理

1.静态资源服务器搭建 1 /*加载模块*/ 2 var express = require('express'); 3 var http = require('http'); 4 var path = require('path'); 5 /*创建服务*/ 6 var app = express(); 7 app.set('port', 80); 8 app.use(express.static(path.join(__dirname, 'public'))); 9 /*服务启动*/ 10 h

Node.js开发札记之一&#183;入门篇

前言: Node.js这个名字并不陌生.刚开始时,以为又是某个团体搞的JS类库.作为jQuery忠实追随者,当时还是比较关注这个异端的出现.后来发现,其实是服务器端的JS.用了J2EE那么多年了,没有心思再去搞这一套.还不如深入写下J2EE的架构什么的.而技术的革新的风暴还是席卷了整个IT界.鄙人再次了开启学习天赋. 环境搭建: 软件下载: 1. Node.js安装包 下载地址(详见官方博客:http://blog.nodejs.org 更新): http://nodejs.org/dist/v

数字对讲系统开发札记（前端linux c 后端 c#）

前言 数字化是一种趋势,特别是在"提速降费"的大环境下,这种趋势愈发明显.对讲机这种古老的系统也处在时代的变革之中,虽然手机的功能越来越强,让人怀疑对讲机是否还有存在的必要.诚然,对讲机仍然有它的市场.有时候,功能太多太强反而不是优势:对讲机的优势就是功能简单,专业性强. 笔者最近也涉足了对讲系统的开发,发现这个行业也大有可为.特别是4G.5G的出现,数字对讲系统的优势逐步显现:就像数码相机代替光学相机,模拟对讲机最终会被数字对讲机代替.虽然笔者接触数字对讲时间并不长:但是敏锐的觉察到

5月份开发问题整理

1.BUG-In android7 phone can not slide above 注:Android 7.0以上,iScroll滑动缓慢迟钝问题解决 What browser are you using? There was a fix to iScroll's handling of passive events in Chrome 55, but a new bug appeared in Chrome 56 (confirmed in the iScroll demos). EDIT

Node.js开发札记之二&#183;页面篇

前言: 原本纠结于Web 模板,选了Handlebars.后来发现页面都是弱逻辑的,不支持复杂逻辑表达式.几乎要放弃之际,想起了Javascript中eval函数.虽然eval函数很强大,强大到可以"凭空"生成对象或执行代码,但总觉得他破坏了代码的优雅性.加之"eval"和"evil"(邪恶)长得挺像的.Eval函数的印象不太好,大多数时候将其当做"禁手".这时候反正也没有什么好办法了.通过Handlebars自定义函数使用e

windows phone开发－Webbrowser使用技巧

5月份开发了脸萌WP版,其中需要使用web技术来绘制图像,于是就使用了原生webbrowser控件.在使用webbrowser control的过程中,发现了一些坑,也总结的几个小技巧,分享给大家. 首先我们需要了解下webbrowser control,与桌面windows平台上的webbrowser一样,都是基于IE内核封装的web展示控件,用法与wpf基本一致,同时也是非托管资源,但wp平台上没有实现IDispose接口,带了了内存控制的挑战.此外,webbrowser本身支持有限的js

c#笔记1-抗变与协变

前言 工作一年了,平时也喜欢看看书,逛逛园子:但说到写博,还真的没有,说到底,只有一个字:懒!现在想改掉这个“毛病”了,希望多把平时工作学习到的知识和遇到的问题记录下来,一是可以梳理自己的思路,加深理解:二是可以向更多的朋友学习和分享:三是可以锻炼自己的写作水平:可谓百利而无一害! 平时偶尔会遇到一些小问题,很多时候都是查了记住,或者简单写写笔记,当时理解就过了,没有形成文档,等过段时间又遇到同样的问题,又要重新去查去理解,甚是麻烦.希望以后把这些东西写成文章,尽管可能是很小的问题,也当做笔记记

使用rapid-framework自动生成struct2

在JavaWeb的开发中,对数据对象的操作不外乎增删改查,不同的数据对象,其action.service.model.jsp等都比较类似,如果手动去写这些代码,工作量大且非常繁琐.一个心高气傲的程序员如果被安排去做干这种活,无论多么有耐心,也会在无休止的琐碎代码中逐渐晕菜.如果有代码工具帮助我们生成这些代码,让coder真正去关注业务逻辑的开发,那肯定是极好的了. 在网上搜索了一下,这种代码自动生成的脚手架scaffold(不是Scofield,scofield是越狱的小帅)有两种,一种是Rai