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HttpHandler在Asp.net中核心对像之一,我们可以实现IHttpHandler接口来优化Css样式文件. 用一个我们自定义的HttpHandler映射.css的文件. 我们定义一个IFilesCache的接口,是为了实现两种不能缓存方式.一种是有用System.Web.Caching.Cache,别一个是用.net 4.0下System.Runtime.Caching.ObjectCache的内存Cache. 我们定义一个FilesCacheFactory的类根据.net framework当前版来在创建 1: /// <summary> 2: /// MinifyCssHandler 3: /// </summary> 4: public class MinifyCssHandler:IHttpHandler 5: {
6: private IFilesCache cacheContext; 7:
8: /// <summary> 9: /// Initializes a new instance of the <see cref="MinifyCssHandler"/> class. 10: /// </summary> 11: public MinifyCssHandler() 12: {
13: cacheContext = FilesCacheFactory.GetInstance();
14: }
15:
16: #region IHttpHandler Members 17:
18: /// <summary> 19: /// Gets a value indicating whether another request can use the <see cref="T:System.Web.IHttpHandler"/> instance. 20: /// </summary> 21: /// <returns>true if the <see cref="T:System.Web.IHttpHandler"/> instance is reusable; otherwise, false.</returns> 22: public bool IsReusable 23: {
24: get { return true; } 25: }
26:
27: /// <summary> 28: /// Enables processing of HTTP Web requests by a custom HttpHandler that implements the <see cref="T:System.Web.IHttpHandler"/> interface. 29: /// </summary> 30: /// <param name="context">An <see cref="T:System.Web.HttpContext"/> object that provides references to the intrinsic server objects (for example, Request, Response, Session, and Server) used to service HTTP requests.</param> 31: public void ProcessRequest(HttpContext context) 32: {
33: string fileContent = string.Empty; 34: string filePath = context.Request.PhysicalPath; 35:
36: string cacheKey = string.Concat("css-", filePath); 37:
38: object cacheValue = cacheContext.GetFromCache(cacheKey); 39:
40: if (cacheValue == null) 41: {
42: fileContent = MinifyFiles(filePath);
43: cacheContext.AddToCache(cacheKey, fileContent, filePath);
44: }
45: else 46: {
47: fileContent = cacheValue as string; 48: }
49: context.Response.ContentType = "text/css"; 50: context.Response.Write(fileContent);
51: }
52:
53: #endregion 54:
55: /// <summary> 56: /// MinifyFiles intent to minfiy css files size 57: /// </summary> 58: /// <param name="filePath">css file path</param> 59: /// <returns>css file of content</returns> 60: private string MinifyFiles(string filePath) 61: {
62: string fileContent = File.ReadAllText(filePath); 63: fileContent = string.Concat("/* minifyed at ", DateTime.Now, " by Petter Liu */ ", fileContent); 64: fileContent = Regex.Replace(fileContent, "\t", string.Empty); 65: fileContent = Regex.Replace(fileContent, "\r\n", string.Empty); 66: fileContent = Regex.Replace(fileContent, "\r", string.Empty); 67: fileContent = Regex.Replace(fileContent, "\n", string.Empty); 68: //Replace more than two spaces 69: fileContent = Regex.Replace(fileContent, "[ ]{2,}", string.Empty); 70: return fileContent; 71: }
72: }
与Cache相关的类: 1: /// <summary> 2: /// IFilesCache 3: /// </summary> 4: public interface IFilesCache 5: {
6: /// <summary> 7: /// Add object to cache 8: /// </summary> 9: /// <param name="key">key</param> 10: /// <param name="value">value</param> 11: /// <param name="filePath">file path</param> 12: void AddToCache(string key, object value, string filePath); 13:
14: /// <summary> 15: /// GetFromCache 16: /// </summary> 17: /// <param name="key">key</param> 18: /// <returns>object</returns> 19: object GetFromCache(string key); 20: }
21:
22: /// <summary> 23: /// a simple factory create IFilesCache 24: /// </summary> 25: public class FilesCacheFactory 26: {
27: /// <summary> 28: /// Create IFilesCache instance 29: /// </summary> 30: /// <remarks>System.Runtime.Caching only runtime at .net framework version 4</remarks> 31: /// <returns>IFilesCache</returns> 32: public static IFilesCache GetInstance() 33: {
34: if (Environment.Version.Major==4) 35: return new DotnetRunningCache(); 36: return new WebContextCache(); 37: }
38:
39: }
40:
41: public class WebContextCache:IFilesCache 42: {
43: #region IFilesCache Members 44: /// <summary> 45: /// Add object to cache 46: /// </summary> 47: /// <param name="key">key</param> 48: /// <param name="value">value</param> 49: /// <param name="filePath">file path</param> 50: public void AddToCache(string key, object value, string filePath) 51: {
52: //Cache two hour 53: HttpContext.Current.Cache.Insert(key, value, 54: new CacheDependency(filePath), 55: DateTime.Now.AddHours(2),
56: TimeSpan.Zero);
57: }
58:
59: /// <summary> 60: /// GetFromCache 61: /// </summary> 62: /// <param name="key">key</param> 63: /// <returns>object</returns> 64: public object GetFromCache(string key) 65: {
66: if (string.IsNullOrEmpty(key)) 67: return new ArgumentNullException("cache key should not null"); 68: return HttpContext.Current.Cache[key]; 69: }
70:
71: #endregion 72: }
73:
74: public class DotnetRunningCache:IFilesCache 75: {
76: #region IFilesCache Members 77: /// <summary> 78: /// Add object to cache 79: /// </summary> 80: /// <param name="key">key</param> 81: /// <param name="value">value</param> 82: /// <param name="filePath">file path</param> 83: public void AddToCache(string key, object value, string filePath) 84: {
85: ObjectCache cache = MemoryCache.Default;
86: var cacheValue = new[] { value }; 87: var cachepolicy = new CacheItemPolicy(); 88: var filespath=new List<string>(){ filePath}; 89: cachepolicy.AbsoluteExpiration = DateTimeOffset.Now.AddHours(2);
90: cachepolicy.ChangeMonitors.Add(new HostFileChangeMonitor(filespath)); 91:
92: cache.Add(key, cacheValue, cachepolicy);
93: }
94:
95: /// <summary> 96: /// GetFromCache 97: /// </summary> 98: /// <param name="key">key</param> 99: /// <returns>object</returns> 100: public object GetFromCache(string key) 101: {
102: if (string.IsNullOrEmpty(key)) 103: return new ArgumentNullException("cache key should not null"); 104:
105: ObjectCache cache = MemoryCache.Default;
106: var objects= (Object[])cache.Get(key);
107: if (objects != null) 108: return objects.FirstOrDefault(); 109: return null; 110: }
111:
112: #endregion 113: }
在Web.config中增加: 1: <httpHandlers> 2: <add verb="*" path="*.css" validate="false" type="MyWeb.MinifyCssHandler"/> 3: </httpHandlers> Ok,对比一下,正常情况下是这样: 当增加这个优化Css的HttpHandler后, 是这样的: 有注意size从4.2KB变成了3.2KB. 以上我们直是实现比较简单的,你可以优化实现更高效的算法. 或增加扩展. 希望这篇Post对您开发有帮助. Petter Liu Blog。 |
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