【Asp】Asp.net程序优化js、css实现合并与压缩的方法-net--程序-优化-js

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Asp.net程序优化js、css实现合并与压缩的方法

public class CombineFiles : IHttpHandler
{
        private const string CacheKeyFormat="_CacheKey_{0}_";

        private const bool IsCompress=true; //需要压缩

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }

        public void ProcessRequest(HttpContext context)
        {
            HttpRequest request=context.Request;
            HttpResponse response=context.Response;

            string cachekey=string.Empty;

            string type=request.QueryString["type"];
            if (!string.IsNullOrEmpty(type) && (type=="css" || type=="js"))
            {
                if (type=="js")
                {
                    response.ContentType="text/javascript";

                }
                else if (type=="css")
                {
                    response.ContentType="text/css";
                }

                cachekey=string.Format(CacheKeyFormat, type);

                CompressCacheItem cacheItem=HttpRuntime.Cache[cachekey] as CompressCacheItem;
                if (cacheItem==null)
                {
                    string content=string.Empty;
                    string path=context.Server.MapPath("");
                    //找到这个目录下所有的js或css文件，当然也可以进行配置，需求请求压缩哪些文件
                    //这里就将所的有文件都请求压缩
                    string[] files=Directory.GetFiles(path, "*." + type);
                    StringBuilder sb=new StringBuilder();
                    foreach (string fileName in files)
                    {
                        if (File.Exists(fileName))
                        {
                            string readstr=File.ReadAllText(fileName, Encoding.UTF8);
                            sb.Append(readstr);
                        }
                    }

                    content=sb.ToString();

                    // 开始压缩文件
                    if (IsCompress)
                    {
                        if (type.Equals("js"))
                        {
                            content=JavaScriptCompressor.Compress(content);
                        }
                        else if (type.Equals("css"))
                        {
                            content=CssCompressor.Compress(content);
                        }
                    }

                    //输入到客户端还可以进行Gzip压缩 ,这里就省略了

                    cacheItem=new CompressCacheItem() { Type=type, Content=content, Expires=DateTime.Now.AddDays(30) };
                    HttpRuntime.Cache.Insert(cachekey, cacheItem, null, cacheItem.Expires, TimeSpan.Zero);
                }

                string ifModifiedSince=request.Headers["If-Modified-Since"];
                if (!string.IsNullOrEmpty(ifModifiedSince)
                    && TimeSpan.FromTicks(cacheItem.Expires.Ticks - DateTime.Parse(ifModifiedSince).Ticks).Seconds < 0)
                {
                    response.StatusCode=(int)System.Net.HttpStatusCode.NotModified;
                    response.StatusDescription="Not Modified";
                }
                else
                {
                    response.Write(cacheItem.Content);
                    SetClientCaching(response, cacheItem.Expires);
                }
            }
        }

        private void SetClientCaching(HttpResponse response, DateTime expires)
        {
            response.Cache.SetETag(DateTime.Now.Ticks.ToString());
            response.Cache.SetLastModified(DateTime.Now);

            //public 以指定响应能由客户端和共享（代理）缓存进行缓存。   
            response.Cache.SetCacheability(HttpCacheability.Public);

            //是允许文档在被视为陈旧之前存在的最长绝对时间。
            response.Cache.SetMaxAge(TimeSpan.FromTicks(expires.Ticks));

            response.Cache.SetSlidingExpiration(true);
        }
        private class CompressCacheItem
        {
            /// <summary>
            /// 类型 js 或 css
            /// </summary>
            public string Type { get; set; } // js css 
            /// <summary>
            /// 内容
            /// </summary>
            public string Content { set; get; }
            /// <summary>
            /// 过期时间
            /// </summary>
            public DateTime Expires { set; get; }
        }
}

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