Asp.net程序优化js、css实现合并与压缩的方法

本文实例讲述了asp.net程序优化js、css实现合并与压缩的方法。分享给大家供大家参考。具体实现方法如下：

访问时将js和css压缩并且缓存在客户端,
采用的是yahoo.yui.compressor组件来完成的,用户可以点击此处本站下载。

创建一个ihttphandler来处理文件

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; }
        }
}

最后在配置文件中配置一下combinefiles.axd文件，具体配置略

引用如下

<script type="text/javascript" src="/js/combinefiles.axd?type=js"></script>
<link rel="stylesheet" type="text/css" href="/css/combinefiles.axd?type=css" />

希望本文所述对大家的asp.net程序设计有所帮助。