ASP.Net 重写IHttpModule 来拦截 HttpApplication 实现HTML资源压缩和空白过滤

发布：2021/7/13 16:37:22作者：管理员来源：本站浏览次数：994

务实直接上代码：

1. 重写FilterModule.cs

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1 using System;

2 using System.Collections.Generic;

3 using System.Linq;

4 using System.Text;

5 using System.Threading.Tasks;

6 using System.Web;

7 using System.Text.RegularExpressions;

8 using System.IO.Compression;

10 namespace Compress.FilterModule

11 {

12 public class FilterModule : IHttpModule

13 {

14 public void Dispose()

15 {

16 //

17 }

19 /// <summary>

20 /// Init method is only used to register the desired event

21 /// </summary>

22 /// <param name="context"></param>

23 public void Init(HttpApplication context)

24 {

25 context.BeginRequest += new EventHandler(context_BeginRequest);

26 //context.EndRequest += new EventHandler(context_EndRequest);

27 //context.PostRequestHandlerExecute += new EventHandler(context_PostRequestHandlerExecute);

28 }

31 /// <summary>

32 /// Handles the BeginRequest event of the context control.

33 /// </summary>

34 /// <param name="sender">The source of the event.</param>

35 /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>

36 void context_BeginRequest(object sender, EventArgs e)

37 {

38 HttpApplication app = sender as HttpApplication;

39 HttpContext context = app.Context;

40 if (context.CurrentHandler is System.Web.UI.Page)

41 {

42 bool isPage = context.CurrentHandler.IsReusable;

43 }

44 if (app.Request.RawUrl.Contains(".aspx") || app.Request.RawUrl.EndsWith("/"))

45 {

46 // HttpContext context = app.Context;

47 HttpRequest request = context.Request;

48 string acceptEncoding = request.Headers["Accept-Encoding"];

49 HttpResponse response = context.Response;

50 if (!string.IsNullOrEmpty(acceptEncoding))

51 {

52 acceptEncoding = acceptEncoding.ToUpperInvariant();

53 if (acceptEncoding.Contains("GZIP"))

54 {

55 //var straem = new GZipStream(response.Filter, CompressionMode.Compress);

56 response.Filter = new CompressWhitespaceFilter(response.Filter, CompressOptions.GZip);

57 response.AppendHeader("Content-encoding", "gzip");

58 }

59 else if (acceptEncoding.Contains("DEFLATE"))

60 {

61 response.Filter = new CompressWhitespaceFilter(context.Response.Filter, CompressOptions.Deflate);

62 response.AppendHeader("Content-encoding", "deflate");

63 }

64 }

65 response.Cache.VaryByHeaders["Accept-Encoding"] = true;

66 }

67 }

69 // Test

70 //void context_BeginRequest(object sender, EventArgs e)

71 //{

72 // HttpApplication application = (HttpApplication)sender;

73 // HttpContext context = application.Context;

74 // context.Response.ContentType = "text/html";

75 // context.Response.Charset = "GB2312";

76 // context.Response.ContentEncoding = Encoding.Default;

77 // context.Response.Write("<h1 style='color:#00f'>Treatment from HttpModule，Begin...</h1><hr>");

78 //}

80 // Test

81 //void context_EndRequest(object sender, EventArgs e)

82 //{

83 // HttpApplication application = (HttpApplication)sender;

84 // HttpContext context = application.Context;

85 // context.Response.ContentType = "text/html";

86 // context.Response.Charset = "GB2312";

87 // context.Response.ContentEncoding = Encoding.Default;

88 // context.Response.Write("<hr><h1 style='color:#f00'>Treatment from HttpModule，End...</h1>");

89 //}

91 }

92 }

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2. 处理压缩和匹配自定义过滤 CompressWhitespaceFilter.cs

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1 using System;

2 using System.Collections.Generic;

3 using System.Linq;

4 using System.Web;

5 using System.IO;

6 using System.Text;

7 using System.Text.RegularExpressions;

8 using System.IO.Compression;

10 namespace Compress.ModuleDemo

11 {

12 public enum CompressOptions

13 {

14 GZip,

15 Deflate,

16 None

17 }

19 public class CompressWhitespaceFilter : Stream

20 {

21 StringBuilder responseHtml;

22 const string _cssPattern = "(?<HTML><link[^>]*href\\s*=\\s*[\\\"\\']?(?<HRef>[^\"'>\\s]*)[\\\"\\']?[^>]*>)";

23 const string _jsPattern = "(?<HTML><script[^>]*src\\s*=\\s*[\\\"\\']?(?<SRC>[^\"'>\\s]*)[\\\"\\']?[^>]*></script>)";

25 private HttpApplication app;

26 public HttpApplication App

27 {

28 get { return app; }

29 set { app = value; }

30 }

32 private GZipStream _contentGZip;

33 private DeflateStream _content_Deflate;

34 private Stream _content;

35 private CompressOptions _options;

36 private bool disposed = false;

38 private CompressWhitespaceFilter() { }

39 public CompressWhitespaceFilter(Stream content, CompressOptions options)

40 {

42 responseHtml = new StringBuilder();

43 if (options == CompressOptions.GZip)

44 {

45 this._contentGZip = new GZipStream(content, CompressionMode.Compress, true);

46 this._content = this._contentGZip;

47 }

48 else if (options == CompressOptions.Deflate)

49 {

50 this._content_Deflate = new DeflateStream(content, CompressionMode.Compress, true);

51 this._content = this._content_Deflate;

52 }

53 else

54 {

55 this._content = content;

56 }

57 this._options = options;

58 }

60 public override bool CanRead

61 {

62 get { return this._content.CanRead; }

63 }

65 public override bool CanSeek

66 {

67 get { return this._content.CanSeek; }

68 }

70 public override bool CanWrite

71 {

72 get { return this._content.CanWrite; }

73 }

75 /// <summary>

76 /// When overriding in a derived class, all buffers of the stream are cleared and all buffer data is written to the underlying device

77 /// </summary>

78 public override void Flush()

79 {

80 this._content.Flush();

81 //Test

82 //this._content.Dispose();

83 //this._contentGZip.Dispose();

84 }

87 /// <summary>

88 /// 重写Dispose方法，释放派生类自己的资源，并且调用基类的Dispose方法

89 /// 使Gzip把缓存中余下的内容全部写入MemoryStream中,因为只有在Gzip流释放之后才能去承载对象中读取数据或判断数据大小

90 /// </summary>

91 /// <param name="disposing"></param>

92 protected override void Dispose(bool disposing)

93 {

94 if (!this.disposed)

95 {

96 try

97 {

98 if (disposing)

99 {

100 // Release the managed resources you added in this derived class here.

101 //xx.Dispose();

102 }

103

104 // Release the native unmanaged resources you added in this derived class here.

105 // xx.Close()

106

107 //if (_contentGZip != null)

108 // _contentGZip.Close();

109

110 //if (_content_Deflate != null)

111 // _content_Deflate.Close();

112

113 this._content.Close();

114 this.disposed = true;

115 }

116 finally

117 {

118 // Call Dispose on your base class.

119 base.Dispose(disposing);

120 }

121 }

122 }

123

124 public override long Length

125 {

126 get { return this._content.Length; }

127 }

128

129 public override long Position

130 {

131 get

132 {

133 return this._content.Position;

134 }

135 set

136 {

137 this._content.Position = value;

138 }

139 }

140

141 public override int Read(byte[] buffer, int offset, int count)

142 {

143 return this._content.Read(buffer, offset, count);

144 }

145

146 public override long Seek(long offset, SeekOrigin origin)

147 {

148 return this._content.Seek(offset, origin);

149 }

150

151 public override void SetLength(long value)

152 {

153 this._content.SetLength(value);

154 }

155

156 public override void Write(byte[] buffer, int offset, int count)

157 {

158 byte[] data = new byte[count + 1];

159 Buffer.BlockCopy(buffer, offset, data, 0, count);

160 string s = System.Text.Encoding.UTF8.GetString(data);

161 s = Regex.Replace(s, "^\\s*", string.Empty, RegexOptions.Compiled | RegexOptions.Multiline);

162 s = Regex.Replace(s, "\\r\\n", string.Empty, RegexOptions.Compiled | RegexOptions.Multiline);

163 s = Regex.Replace(s, "", string.Empty, RegexOptions.Compiled | RegexOptions.Multiline);

164 byte[] outdata = System.Text.Encoding.UTF8.GetBytes(s);

165 this._content.Write(outdata, 0, outdata.GetLength(0));

166 }

167

168

169 /// <summary>

170 /// Replcase stylesheet links with ones pointing to HttpHandlers that compress and cache the css

171 /// </summary>

172 /// <param name="html"></param>

173 /// <returns></returns>

174 public string ReplaceCss(string html)

175 {

176 // create a list of the stylesheets

177 List<string> stylesheets = new List<string>();

178 // create a dictionary used for combining css in the same directory

179 Dictionary<string, List<string>> css = new Dictionary<string, List<string>>();

180

181 // create a base uri which will be used to get the uris to the css

182 Uri baseUri = new Uri(app.Request.Url.AbsoluteUri);

183

184 // loop through each match

185 foreach (Match match in Regex.Matches(html, _cssPattern, RegexOptions.IgnoreCase))

186 {

187 // this is the enire match and will be used to replace the link

188 string linkHtml = match.Groups[0].Value;

189 // this is the href of the link

190 string href = match.Groups[2].Value;

191

192 // get a uri from the base uri, this will resolve any relative and absolute links

193 Uri uri = new Uri(baseUri, href);

194 string file = "";

195 // check to see if it is a link to a local file

196 if (uri.Host == baseUri.Host)

197 {

198 // check to see if it is local to the application

199 if (uri.AbsolutePath.ToLower().StartsWith(app.Context.Request.ApplicationPath.ToLower()))

200 {

201 // this combines css files in the same directory into one file (actual combining done in HttpHandler)

202 int index = uri.AbsolutePath.LastIndexOf("/");

203 string path = uri.AbsolutePath.Substring(0, index + 1);

204 file = uri.AbsolutePath.Substring(index + 1);

205 if (!css.ContainsKey(path))

206 css.Add(path, new List<string>());

207 css[path].Add(file + (href.Contains("?") ? href.Substring(href.IndexOf("?")) : ""));

208 // replace the origianl links with blanks

209 html = html.Replace(linkHtml, "");

210 // continue to next link

211 continue;

212 }

213 else

214 file = uri.AbsolutePath + uri.Query;

215 }

216 else

217 file = uri.AbsoluteUri;

218 string newLinkHtml = linkHtml.Replace(href, "css.axd?files=" + file);

219

220 // just replace the link with the new link

221 html = html.Replace(linkHtml, newLinkHtml);

222 }

223

224 StringBuilder link = new StringBuilder();

225 link.AppendLine("");

226 foreach (string key in css.Keys)

227 {

228 link.AppendLine(string.Format("<link href='{0}css.axd?files={1}' type='text/css' rel='stylesheet' />", key, string.Join(",", css[key].ToArray())));

229

230 }

231

232 // find the head tag and insert css in the head tag

233 int x = html.IndexOf("<head");

234 int num = 0;

235 if (x > -1)

236 {

237 num = html.Substring(x).IndexOf(">");

238 html = html.Insert(x + num + 1, link.ToString());

239 }

240 return html;

241 }

242

243 /// <summary>

244 /// Replcase javascript links with ones pointing to HttpHandlers that compress and cache the javascript

245 /// </summary>

246 /// <param name="html"></param>

247 /// <returns></returns>

248 public string ReplaceJS(string html)

249 {

250 // if the javascript is in the head section of the html, then try to combine the javascript into one

251 int start, end;

252 if (html.Contains("<head") && html.Contains("</head>"))

253 {

254 start = html.IndexOf("<head");

255 end = html.IndexOf("</head>");

256 string head = html.Substring(start, end - start);

257

258 head = ReplaceJSInHead(head);

259

260 html = html.Substring(0, start) + head + html.Substring(end);

261 }

262

263 // javascript that is referenced in the body is usually used to write content to the page via javascript,

264 // we don't want to combine these and place them in the header since it would cause problems

265 // or it is a WebResource.axd or ScriptResource.axd

266 if (html.Contains("<body") && html.Contains("</body>"))

267 {

268 start = html.IndexOf("<body");

269 end = html.IndexOf("</body>");

270 string head = html.Substring(start, end - start);

271

272 head = ReplaceJSInBody(head);

273

274 html = html.Substring(0, start) + head + html.Substring(end);

275 }

276

277 return html;

278 }

279

280 /// <summary>

281 /// Replaces the js in the head tag. (see ReplaceCss for comments)

282 /// </summary>

283 /// <param name="html"></param>

284 /// <returns></returns>

285 public string ReplaceJSInHead(string html)

286 {

287 List<string> javascript = new List<string>();

288 Dictionary<string, List<string>> js = new Dictionary<string, List<string>>();

289

290 Uri baseUri = new Uri(app.Request.Url.AbsoluteUri);

291 foreach (Match match in Regex.Matches(html, _jsPattern, RegexOptions.IgnoreCase))

292 {

293 string linkHtml = match.Groups[0].Value;

294 string src = match.Groups[2].Value;

295

296 Uri uri = new Uri(baseUri, src);

297 if (!Path.GetExtension(uri.AbsolutePath).Equals("js") && uri.AbsolutePath.Contains("WebResource.axd"))

298 continue;

299 if (uri.Host == baseUri.Host)

300 {

301 if (uri.AbsolutePath.ToLower().StartsWith(app.Context.Request.ApplicationPath.ToLower()))

302 {

303 int index = uri.AbsolutePath.LastIndexOf("/");

304 string path = uri.AbsolutePath.Substring(0, index + 1);

305 string file = uri.AbsolutePath.Substring(index + 1);

306 if (!js.ContainsKey(path))

307 js.Add(path, new List<string>());

308 js[path].Add(file + (src.Contains("?") ? src.Substring(src.IndexOf("?")) : ""));

309 }

310 else

311 javascript.Add(uri.AbsolutePath + uri.Query);

312

313 }

314 else

315 javascript.Add(uri.AbsoluteUri);

316 html = html.Replace(linkHtml, "");

317 }

318

319 int x = html.IndexOf("<head");

320 int num = html.Substring(x).IndexOf(">");

321 string link = "";

322

323 foreach (string key in js.Keys)

324 {

325 link = string.Format("<script src='{0}js.axd?files={1}' type='text/javascript' ></script>", key, string.Join(",", js[key].ToArray()));

326 html = html.Insert(x + num + 1, link + Environment.NewLine);

327

328 }

329 if (javascript.Count > 0)

330 {

331 link = string.Format("<script src='js.axd?files={0}' type='text/javascript' /></script>", string.Join(",", javascript.ToArray()));

332 html = html.Insert(x + num + 1, link + Environment.NewLine);

333 }

334 return html;

335 }

336

337 /// <summary>

338 /// Replaces the js in the body. (see ReplaceCss for comments)

339 /// </summary>

340 /// <param name="html"></param>

341 /// <returns></returns>

342 public string ReplaceJSInBody(string html)

343 {

344 Uri baseUri = new Uri(app.Request.Url.AbsoluteUri);

345 foreach (Match match in Regex.Matches(html, _jsPattern, RegexOptions.IgnoreCase))

346 {

347 string linkHtml = match.Groups[0].Value;

348 string src = match.Groups[2].Value;

349

350

351 Uri uri = new Uri(baseUri, src);

352 if (!uri.AbsolutePath.EndsWith(".js") && !uri.AbsolutePath.Contains("WebResource.axd"))

353 continue;

354 string file = "";

355 string path = "";

356 if (uri.Host == baseUri.Host)

357 {

358 if (uri.AbsolutePath.ToLower().StartsWith(app.Context.Request.ApplicationPath.ToLower()))

359 {

360 int index = uri.AbsolutePath.LastIndexOf("/");

361 path = uri.AbsolutePath.Substring(0, index + 1);

362 file = uri.AbsolutePath.Substring(index + 1) + (src.Contains("?") ? src.Substring(src.IndexOf("?")) : "");

363 }

364 else

365 file = uri.AbsolutePath + uri.Query;

366 }

367 else

368 file = uri.AbsoluteUri;

369 string newLinkHtml = linkHtml.Replace(src, path + "js.axd?files=" + file);

370 html = html.Replace(linkHtml, newLinkHtml);

371 }

372 return html;

373 }

374

375 }

376 }

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在这里需要注意的是对GZIP 的释放，否则流数据会读取不到：

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1 /// <summary>

2 /// 重写Dispose方法，释放派生类自己的资源，并且调用基类的Dispose方法

3 /// 使Gzip把缓存中余下的内容全部写入MemoryStream中,因为只有在Gzip流释放之后才能去承载对象中读取数据或判断数据大小

4 /// </summary>

5 /// <param name="disposing"></param>

6 protected override void Dispose(bool disposing)

7 {

8 if (!this.disposed)

9 {

10 try

11 {

12 if (disposing)

13 {

14 // Release the managed resources you added in this derived class here.

15 //xx.Dispose();

16 }

18 // Release the native unmanaged resources you added in this derived class here.

19 // xx.Close()

21 //if (_contentGZip != null)

22 // _contentGZip.Close();

24 //if (_content_Deflate != null)

25 // _content_Deflate.Close();

27 this._content.Close();

28 this.disposed = true;

29 }

30 finally

31 {

32 // Call Dispose on your base class.

33 base.Dispose(disposing);

34 }

35 }

36 }

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对于C#非托管资源释放(Finalize/Dispose)方法理解：

http://www.cnblogs.com/lzhdim/archive/2009/11/04/1595845.html

　C#非托管资源释放(Finalize&Dispose)方法

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