1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package javax.servlet.http;
18
19 import java.io.IOException;
20 import java.io.PrintWriter;
21 import java.io.OutputStreamWriter;
22 import java.io.UnsupportedEncodingException;
23 import java.lang.reflect.Method;
24 import java.text.MessageFormat;
25 import java.util.Enumeration;
26 import java.util.ResourceBundle;
27
28 import javax.servlet.GenericServlet;
29 import javax.servlet.ServletException;
30 import javax.servlet.ServletOutputStream;
31 import javax.servlet.ServletRequest;
32 import javax.servlet.ServletResponse;
33
34
35 /**
36 * Provides an abstract class to be subclassed to create
37 * an HTTP servlet suitable for a Web site. A subclass of
38 * <code>HttpServlet</code> must override at least
39 * one method, usually one of these:
40 *
41 * <ul>
42 * <li> <code>doGet</code>, if the servlet supports HTTP GET requests
43 * <li> <code>doPost</code>, for HTTP POST requests
44 * <li> <code>doPut</code>, for HTTP PUT requests
45 * <li> <code>doDelete</code>, for HTTP DELETE requests
46 * <li> <code>init</code> and <code>destroy</code>,
47 * to manage resources that are held for the life of the servlet
48 * <li> <code>getServletInfo</code>, which the servlet uses to
49 * provide information about itself
50 * </ul>
51 *
52 * <p>There's almost no reason to override the <code>service</code>
53 * method. <code>service</code> handles standard HTTP
54 * requests by dispatching them to the handler methods
55 * for each HTTP request type (the <code>do</code><i>XXX</i>
56 * methods listed above).
57 *
58 * <p>Likewise, there's almost no reason to override the
59 * <code>doOptions</code> and <code>doTrace</code> methods.
60 *
61 * <p>Servlets typically run on multithreaded servers,
62 * so be aware that a servlet must handle concurrent
63 * requests and be careful to synchronize access to shared resources.
64 * Shared resources include in-memory data such as
65 * instance or class variables and external objects
66 * such as files, database connections, and network
67 * connections.
68 * See the
69 * <a href="http://java.sun.com/Series/Tutorial/java/threads/multithreaded.html">
70 * Java Tutorial on Multithreaded Programming</a> for more
71 * information on handling multiple threads in a Java program.
72 *
73 * @author Various
74 * @version $Version$
75 */
76 public abstract class HttpServlet extends GenericServlet
77 implements java.io.Serializable {
78
79 private static final String METHOD_DELETE = "DELETE";
80 private static final String METHOD_HEAD = "HEAD";
81 private static final String METHOD_GET = "GET";
82 private static final String METHOD_OPTIONS = "OPTIONS";
83 private static final String METHOD_POST = "POST";
84 private static final String METHOD_PUT = "PUT";
85 private static final String METHOD_TRACE = "TRACE";
86
87 private static final String HEADER_IFMODSINCE = "If-Modified-Since";
88 private static final String HEADER_LASTMOD = "Last-Modified";
89
90 private static final String LSTRING_FILE =
91 "javax.servlet.http.LocalStrings";
92 private static ResourceBundle lStrings =
93 ResourceBundle.getBundle(LSTRING_FILE);
94
95
96 /**
97 * Does nothing, because this is an abstract class.
98 */
99 public HttpServlet() { }
100
101
102 /**
103 * Called by the server (via the <code>service</code> method) to
104 * allow a servlet to handle a GET request.
105 *
106 * <p>Overriding this method to support a GET request also
107 * automatically supports an HTTP HEAD request. A HEAD
108 * request is a GET request that returns no body in the
109 * response, only the request header fields.
110 *
111 * <p>When overriding this method, read the request data,
112 * write the response headers, get the response's writer or
113 * output stream object, and finally, write the response data.
114 * It's best to include content type and encoding. When using
115 * a <code>PrintWriter</code> object to return the response,
116 * set the content type before accessing the
117 * <code>PrintWriter</code> object.
118 *
119 * <p>The servlet container must write the headers before
120 * committing the response, because in HTTP the headers must be sent
121 * before the response body.
122 *
123 * <p>Where possible, set the Content-Length header (with the
124 * {@link javax.servlet.ServletResponse#setContentLength} method),
125 * to allow the servlet container to use a persistent connection
126 * to return its response to the client, improving performance.
127 * The content length is automatically set if the entire response fits
128 * inside the response buffer.
129 *
130 * <p>When using HTTP 1.1 chunked encoding (which means that the response
131 * has a Transfer-Encoding header), do not set the Content-Length header.
132 *
133 * <p>The GET method should be safe, that is, without
134 * any side effects for which users are held responsible.
135 * For example, most form queries have no side effects.
136 * If a client request is intended to change stored data,
137 * the request should use some other HTTP method.
138 *
139 * <p>The GET method should also be idempotent, meaning
140 * that it can be safely repeated. Sometimes making a
141 * method safe also makes it idempotent. For example,
142 * repeating queries is both safe and idempotent, but
143 * buying a product online or modifying data is neither
144 * safe nor idempotent.
145 *
146 * <p>If the request is incorrectly formatted, <code>doGet</code>
147 * returns an HTTP "Bad Request" message.
148 *
149 * @param req an {@link HttpServletRequest} object that
150 * contains the request the client has made
151 * of the servlet
152 *
153 * @param resp an {@link HttpServletResponse} object that
154 * contains the response the servlet sends
155 * to the client
156 *
157 * @exception IOException if an input or output error is
158 * detected when the servlet handles
159 * the GET request
160 *
161 * @exception ServletException if the request for the GET
162 * could not be handled
163 *
164 * @see javax.servlet.ServletResponse#setContentType
165 */
166 protected void doGet(HttpServletRequest req, HttpServletResponse resp)
167 throws ServletException, IOException
168 {
169 String protocol = req.getProtocol();
170 String msg = lStrings.getString("http.method_get_not_supported");
171 if (protocol.endsWith("1.1")) {
172 resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
173 } else {
174 resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
175 }
176 }
177
178
179 /**
180 * Returns the time the <code>HttpServletRequest</code>
181 * object was last modified,
182 * in milliseconds since midnight January 1, 1970 GMT.
183 * If the time is unknown, this method returns a negative
184 * number (the default).
185 *
186 * <p>Servlets that support HTTP GET requests and can quickly determine
187 * their last modification time should override this method.
188 * This makes browser and proxy caches work more effectively,
189 * reducing the load on server and network resources.
190 *
191 * @param req the <code>HttpServletRequest</code>
192 * object that is sent to the servlet
193 *
194 * @return a <code>long</code> integer specifying
195 * the time the <code>HttpServletRequest</code>
196 * object was last modified, in milliseconds
197 * since midnight, January 1, 1970 GMT, or
198 * -1 if the time is not known
199 */
200 protected long getLastModified(HttpServletRequest req) {
201 return -1;
202 }
203
204
205 /**
206 * <p>Receives an HTTP HEAD request from the protected
207 * <code>service</code> method and handles the
208 * request.
209 * The client sends a HEAD request when it wants
210 * to see only the headers of a response, such as
211 * Content-Type or Content-Length. The HTTP HEAD
212 * method counts the output bytes in the response
213 * to set the Content-Length header accurately.
214 *
215 * <p>If you override this method, you can avoid computing
216 * the response body and just set the response headers
217 * directly to improve performance. Make sure that the
218 * <code>doHead</code> method you write is both safe
219 * and idempotent (that is, protects itself from being
220 * called multiple times for one HTTP HEAD request).
221 *
222 * <p>If the HTTP HEAD request is incorrectly formatted,
223 * <code>doHead</code> returns an HTTP "Bad Request"
224 * message.
225 *
226 * @param req the request object that is passed to the servlet
227 *
228 * @param resp the response object that the servlet
229 * uses to return the headers to the clien
230 *
231 * @exception IOException if an input or output error occurs
232 *
233 * @exception ServletException if the request for the HEAD
234 * could not be handled
235 */
236 protected void doHead(HttpServletRequest req, HttpServletResponse resp)
237 throws ServletException, IOException {
238
239 NoBodyResponse response = new NoBodyResponse(resp);
240
241 doGet(req, response);
242 response.setContentLength();
243 }
244
245
246 /**
247 * Called by the server (via the <code>service</code> method)
248 * to allow a servlet to handle a POST request.
249 *
250 * The HTTP POST method allows the client to send
251 * data of unlimited length to the Web server a single time
252 * and is useful when posting information such as
253 * credit card numbers.
254 *
255 * <p>When overriding this method, read the request data,
256 * write the response headers, get the response's writer or output
257 * stream object, and finally, write the response data. It's best
258 * to include content type and encoding. When using a
259 * <code>PrintWriter</code> object to return the response, set the
260 * content type before accessing the <code>PrintWriter</code> object.
261 *
262 * <p>The servlet container must write the headers before committing the
263 * response, because in HTTP the headers must be sent before the
264 * response body.
265 *
266 * <p>Where possible, set the Content-Length header (with the
267 * {@link javax.servlet.ServletResponse#setContentLength} method),
268 * to allow the servlet container to use a persistent connection
269 * to return its response to the client, improving performance.
270 * The content length is automatically set if the entire response fits
271 * inside the response buffer.
272 *
273 * <p>When using HTTP 1.1 chunked encoding (which means that the response
274 * has a Transfer-Encoding header), do not set the Content-Length header.
275 *
276 * <p>This method does not need to be either safe or idempotent.
277 * Operations requested through POST can have side effects for
278 * which the user can be held accountable, for example,
279 * updating stored data or buying items online.
280 *
281 * <p>If the HTTP POST request is incorrectly formatted,
282 * <code>doPost</code> returns an HTTP "Bad Request" message.
283 *
284 *
285 * @param req an {@link HttpServletRequest} object that
286 * contains the request the client has made
287 * of the servlet
288 *
289 * @param resp an {@link HttpServletResponse} object that
290 * contains the response the servlet sends
291 * to the client
292 *
293 * @exception IOException if an input or output error is
294 * detected when the servlet handles
295 * the request
296 *
297 * @exception ServletException if the request for the POST
298 * could not be handled
299 *
300 * @see javax.servlet.ServletOutputStream
301 * @see javax.servlet.ServletResponse#setContentType
302 */
303 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
304 throws ServletException, IOException {
305
306 String protocol = req.getProtocol();
307 String msg = lStrings.getString("http.method_post_not_supported");
308 if (protocol.endsWith("1.1")) {
309 resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
310 } else {
311 resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
312 }
313 }
314
315
316 /**
317 * Called by the server (via the <code>service</code> method)
318 * to allow a servlet to handle a PUT request.
319 *
320 * The PUT operation allows a client to
321 * place a file on the server and is similar to
322 * sending a file by FTP.
323 *
324 * <p>When overriding this method, leave intact
325 * any content headers sent with the request (including
326 * Content-Length, Content-Type, Content-Transfer-Encoding,
327 * Content-Encoding, Content-Base, Content-Language, Content-Location,
328 * Content-MD5, and Content-Range). If your method cannot
329 * handle a content header, it must issue an error message
330 * (HTTP 501 - Not Implemented) and discard the request.
331 * For more information on HTTP 1.1, see RFC 2616
332 * <a href="http://www.ietf.org/rfc/rfc2616.txt"></a>.
333 *
334 * <p>This method does not need to be either safe or idempotent.
335 * Operations that <code>doPut</code> performs can have side
336 * effects for which the user can be held accountable. When using
337 * this method, it may be useful to save a copy of the
338 * affected URL in temporary storage.
339 *
340 * <p>If the HTTP PUT request is incorrectly formatted,
341 * <code>doPut</code> returns an HTTP "Bad Request" message.
342 *
343 * @param req the {@link HttpServletRequest} object that
344 * contains the request the client made of
345 * the servlet
346 *
347 * @param resp the {@link HttpServletResponse} object that
348 * contains the response the servlet returns
349 * to the client
350 *
351 * @exception IOException if an input or output error occurs
352 * while the servlet is handling the
353 * PUT request
354 *
355 * @exception ServletException if the request for the PUT
356 * cannot be handled
357 */
358 protected void doPut(HttpServletRequest req, HttpServletResponse resp)
359 throws ServletException, IOException {
360
361 String protocol = req.getProtocol();
362 String msg = lStrings.getString("http.method_put_not_supported");
363 if (protocol.endsWith("1.1")) {
364 resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
365 } else {
366 resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
367 }
368 }
369
370
371 /**
372 * Called by the server (via the <code>service</code> method)
373 * to allow a servlet to handle a DELETE request.
374 *
375 * The DELETE operation allows a client to remove a document
376 * or Web page from the server.
377 *
378 * <p>This method does not need to be either safe
379 * or idempotent. Operations requested through
380 * DELETE can have side effects for which users
381 * can be held accountable. When using
382 * this method, it may be useful to save a copy of the
383 * affected URL in temporary storage.
384 *
385 * <p>If the HTTP DELETE request is incorrectly formatted,
386 * <code>doDelete</code> returns an HTTP "Bad Request"
387 * message.
388 *
389 * @param req the {@link HttpServletRequest} object that
390 * contains the request the client made of
391 * the servlet
392 *
393 *
394 * @param resp the {@link HttpServletResponse} object that
395 * contains the response the servlet returns
396 * to the client
397 *
398 * @exception IOException if an input or output error occurs
399 * while the servlet is handling the
400 * DELETE request
401 *
402 * @exception ServletException if the request for the
403 * DELETE cannot be handled
404 */
405 protected void doDelete(HttpServletRequest req,
406 HttpServletResponse resp)
407 throws ServletException, IOException {
408
409 String protocol = req.getProtocol();
410 String msg = lStrings.getString("http.method_delete_not_supported");
411 if (protocol.endsWith("1.1")) {
412 resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
413 } else {
414 resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
415 }
416 }
417
418
419 private static Method[] getAllDeclaredMethods(Class c) {
420
421 if (c.equals(javax.servlet.http.HttpServlet.class)) {
422 return null;
423 }
424
425 Method[] parentMethods = getAllDeclaredMethods(c.getSuperclass());
426 Method[] thisMethods = c.getDeclaredMethods();
427
428 if ((parentMethods != null) && (parentMethods.length > 0)) {
429 Method[] allMethods =
430 new Method[parentMethods.length + thisMethods.length];
431 System.arraycopy(parentMethods, 0, allMethods, 0,
432 parentMethods.length);
433 System.arraycopy(thisMethods, 0, allMethods, parentMethods.length,
434 thisMethods.length);
435
436 thisMethods = allMethods;
437 }
438
439 return thisMethods;
440 }
441
442
443 /**
444 * Called by the server (via the <code>service</code> method)
445 * to allow a servlet to handle a OPTIONS request.
446 *
447 * The OPTIONS request determines which HTTP methods
448 * the server supports and
449 * returns an appropriate header. For example, if a servlet
450 * overrides <code>doGet</code>, this method returns the
451 * following header:
452 *
453 * <p><code>Allow: GET, HEAD, TRACE, OPTIONS</code>
454 *
455 * <p>There's no need to override this method unless the
456 * servlet implements new HTTP methods, beyond those
457 * implemented by HTTP 1.1.
458 *
459 * @param req the {@link HttpServletRequest} object that
460 * contains the request the client made of
461 * the servlet
462 *
463 * @param resp the {@link HttpServletResponse} object that
464 * contains the response the servlet returns
465 * to the client
466 *
467 * @exception IOException if an input or output error occurs
468 * while the servlet is handling the
469 * OPTIONS request
470 *
471 * @exception ServletException if the request for the
472 * OPTIONS cannot be handled
473 */
474 protected void doOptions(HttpServletRequest req, HttpServletResponse resp)
475 throws ServletException, IOException {
476
477 Method[] methods = getAllDeclaredMethods(this.getClass());
478
479 boolean ALLOW_GET = false;
480 boolean ALLOW_HEAD = false;
481 boolean ALLOW_POST = false;
482 boolean ALLOW_PUT = false;
483 boolean ALLOW_DELETE = false;
484 boolean ALLOW_TRACE = true;
485 boolean ALLOW_OPTIONS = true;
486
487 for (int i=0; i<methods.length; i++) {
488 Method m = methods[i];
489
490 if (m.getName().equals("doGet")) {
491 ALLOW_GET = true;
492 ALLOW_HEAD = true;
493 }
494 if (m.getName().equals("doPost"))
495 ALLOW_POST = true;
496 if (m.getName().equals("doPut"))
497 ALLOW_PUT = true;
498 if (m.getName().equals("doDelete"))
499 ALLOW_DELETE = true;
500 }
501
502 String allow = null;
503 if (ALLOW_GET)
504 if (allow==null) allow=METHOD_GET;
505 if (ALLOW_HEAD)
506 if (allow==null) allow=METHOD_HEAD;
507 else allow += ", " + METHOD_HEAD;
508 if (ALLOW_POST)
509 if (allow==null) allow=METHOD_POST;
510 else allow += ", " + METHOD_POST;
511 if (ALLOW_PUT)
512 if (allow==null) allow=METHOD_PUT;
513 else allow += ", " + METHOD_PUT;
514 if (ALLOW_DELETE)
515 if (allow==null) allow=METHOD_DELETE;
516 else allow += ", " + METHOD_DELETE;
517 if (ALLOW_TRACE)
518 if (allow==null) allow=METHOD_TRACE;
519 else allow += ", " + METHOD_TRACE;
520 if (ALLOW_OPTIONS)
521 if (allow==null) allow=METHOD_OPTIONS;
522 else allow += ", " + METHOD_OPTIONS;
523
524 resp.setHeader("Allow", allow);
525 }
526
527
528 /**
529 * Called by the server (via the <code>service</code> method)
530 * to allow a servlet to handle a TRACE request.
531 *
532 * A TRACE returns the headers sent with the TRACE
533 * request to the client, so that they can be used in
534 * debugging. There's no need to override this method.
535 *
536 * @param req the {@link HttpServletRequest} object that
537 * contains the request the client made of
538 * the servlet
539 *
540 * @param resp the {@link HttpServletResponse} object that
541 * contains the response the servlet returns
542 * to the client
543 *
544 * @exception IOException if an input or output error occurs
545 * while the servlet is handling the
546 * TRACE request
547 *
548 * @exception ServletException if the request for the
549 * TRACE cannot be handled
550 */
551 protected void doTrace(HttpServletRequest req, HttpServletResponse resp)
552 throws ServletException, IOException
553 {
554
555 int responseLength;
556
557 String CRLF = "\r\n";
558 String responseString = "TRACE "+ req.getRequestURI()+
559 " " + req.getProtocol();
560
561 Enumeration reqHeaderEnum = req.getHeaderNames();
562
563 while( reqHeaderEnum.hasMoreElements() ) {
564 String headerName = (String)reqHeaderEnum.nextElement();
565 responseString += CRLF + headerName + ": " +
566 req.getHeader(headerName);
567 }
568
569 responseString += CRLF;
570
571 responseLength = responseString.length();
572
573 resp.setContentType("message/http");
574 resp.setContentLength(responseLength);
575 ServletOutputStream out = resp.getOutputStream();
576 out.print(responseString);
577 out.close();
578 return;
579 }
580
581
582 /**
583 * Receives standard HTTP requests from the public
584 * <code>service</code> method and dispatches
585 * them to the <code>do</code><i>XXX</i> methods defined in
586 * this class. This method is an HTTP-specific version of the
587 * {@link javax.servlet.Servlet#service} method. There's no
588 * need to override this method.
589 *
590 * @param req the {@link HttpServletRequest} object that
591 * contains the request the client made of
592 * the servlet
593 *
594 * @param resp the {@link HttpServletResponse} object that
595 * contains the response the servlet returns
596 * to the client
597 *
598 * @exception IOException if an input or output error occurs
599 * while the servlet is handling the
600 * HTTP request
601 *
602 * @exception ServletException if the HTTP request
603 * cannot be handled
604 *
605 * @see javax.servlet.Servlet#service
606 */
607 protected void service(HttpServletRequest req, HttpServletResponse resp)
608 throws ServletException, IOException {
609
610 String method = req.getMethod();
611
612 if (method.equals(METHOD_GET)) {
613 long lastModified = getLastModified(req);
614 if (lastModified == -1) {
615 // servlet doesn't support if-modified-since, no reason
616 // to go through further expensive logic
617 doGet(req, resp);
618 } else {
619 long ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE);
620 if (ifModifiedSince < (lastModified / 1000 * 1000)) {
621 // If the servlet mod time is later, call doGet()
622 // Round down to the nearest second for a proper compare
623 // A ifModifiedSince of -1 will always be less
624 maybeSetLastModified(resp, lastModified);
625 doGet(req, resp);
626 } else {
627 resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
628 }
629 }
630
631 } else if (method.equals(METHOD_HEAD)) {
632 long lastModified = getLastModified(req);
633 maybeSetLastModified(resp, lastModified);
634 doHead(req, resp);
635
636 } else if (method.equals(METHOD_POST)) {
637 doPost(req, resp);
638
639 } else if (method.equals(METHOD_PUT)) {
640 doPut(req, resp);
641
642 } else if (method.equals(METHOD_DELETE)) {
643 doDelete(req, resp);
644
645 } else if (method.equals(METHOD_OPTIONS)) {
646 doOptions(req,resp);
647
648 } else if (method.equals(METHOD_TRACE)) {
649 doTrace(req,resp);
650
651 } else {
652 //
653 // Note that this means NO servlet supports whatever
654 // method was requested, anywhere on this server.
655 //
656
657 String errMsg = lStrings.getString("http.method_not_implemented");
658 Object[] errArgs = new Object[1];
659 errArgs[0] = method;
660 errMsg = MessageFormat.format(errMsg, errArgs);
661
662 resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg);
663 }
664 }
665
666
667 /*
668 * Sets the Last-Modified entity header field, if it has not
669 * already been set and if the value is meaningful. Called before
670 * doGet, to ensure that headers are set before response data is
671 * written. A subclass might have set this header already, so we
672 * check.
673 */
674 private void maybeSetLastModified(HttpServletResponse resp,
675 long lastModified) {
676 if (resp.containsHeader(HEADER_LASTMOD))
677 return;
678 if (lastModified >= 0)
679 resp.setDateHeader(HEADER_LASTMOD, lastModified);
680 }
681
682
683 /**
684 * Dispatches client requests to the protected
685 * <code>service</code> method. There's no need to
686 * override this method.
687 *
688 * @param req the {@link HttpServletRequest} object that
689 * contains the request the client made of
690 * the servlet
691 *
692 * @param res the {@link HttpServletResponse} object that
693 * contains the response the servlet returns
694 * to the client
695 *
696 * @exception IOException if an input or output error occurs
697 * while the servlet is handling the
698 * HTTP request
699 *
700 * @exception ServletException if the HTTP request cannot
701 * be handled
702 *
703 * @see javax.servlet.Servlet#service
704 */
705 public void service(ServletRequest req, ServletResponse res)
706 throws ServletException, IOException {
707
708 HttpServletRequest request;
709 HttpServletResponse response;
710
711 try {
712 request = (HttpServletRequest) req;
713 response = (HttpServletResponse) res;
714 } catch (ClassCastException e) {
715 throw new ServletException("non-HTTP request or response");
716 }
717 service(request, response);
718 }
719 }
720
721
722 /*
723 * A response wrapper for use in (dumb) "HEAD" support.
724 * This just swallows that body, counting the bytes in order to set
725 * the content length appropriately. All other methods delegate to the
726 * wrapped HTTP Servlet Response object.
727 */
728 // file private
729 class NoBodyResponse extends HttpServletResponseWrapper {
730 private NoBodyOutputStream noBody;
731 private PrintWriter writer;
732 private boolean didSetContentLength;
733
734 // file private
735 NoBodyResponse(HttpServletResponse r) {
736 super(r);
737 noBody = new NoBodyOutputStream();
738 }
739
740 // file private
741 void setContentLength() {
742 if (!didSetContentLength)
743 super.setContentLength(noBody.getContentLength());
744 }
745
746
747 // SERVLET RESPONSE interface methods
748
749 public void setContentLength(int len) {
750 super.setContentLength(len);
751 didSetContentLength = true;
752 }
753
754 public ServletOutputStream getOutputStream() throws IOException {
755 return noBody;
756 }
757
758 public PrintWriter getWriter() throws UnsupportedEncodingException {
759
760 if (writer == null) {
761 OutputStreamWriter w;
762
763 w = new OutputStreamWriter(noBody, getCharacterEncoding());
764 writer = new PrintWriter(w);
765 }
766 return writer;
767 }
768 }
769
770
771 /*
772 * Servlet output stream that gobbles up all its data.
773 */
774
775 // file private
776 class NoBodyOutputStream extends ServletOutputStream {
777
778 private static final String LSTRING_FILE =
779 "javax.servlet.http.LocalStrings";
780 private static ResourceBundle lStrings =
781 ResourceBundle.getBundle(LSTRING_FILE);
782
783 private int contentLength = 0;
784
785 // file private
786 NoBodyOutputStream() {}
787
788 // file private
789 int getContentLength() {
790 return contentLength;
791 }
792
793 public void write(int b) {
794 contentLength++;
795 }
796
797 public void write(byte buf[], int offset, int len)
798 throws IOException
799 {
800 if (len >= 0) {
801 contentLength += len;
802 } else {
803 // XXX
804 // isn't this really an IllegalArgumentException?
805
806 String msg = lStrings.getString("err.io.negativelength");
807 throw new IOException(msg);
808 }
809 }
810 }
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