From cbf1ffd0fe5c2210e315e9b254a0d73d777fbfaf Mon Sep 17 00:00:00 2001 From: Arjen Poutsma Date: Thu, 30 Oct 2008 15:29:19 +0000 Subject: [PATCH] SPR-4419: Shallow ETag support git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@207 50f2f4bb-b051-0410-bef5-90022cba6387 --- .../filter/ShallowEtagHeaderFilterTest.java | 93 +++++++++++ .../web/filter/ShallowEtagHeaderFilter.java | 152 ++++++++++++++++++ 2 files changed, 245 insertions(+) create mode 100644 org.springframework.testsuite/src/test/java/org/springframework/web/filter/ShallowEtagHeaderFilterTest.java create mode 100644 org.springframework.web/src/main/java/org/springframework/web/filter/ShallowEtagHeaderFilter.java diff --git a/org.springframework.testsuite/src/test/java/org/springframework/web/filter/ShallowEtagHeaderFilterTest.java b/org.springframework.testsuite/src/test/java/org/springframework/web/filter/ShallowEtagHeaderFilterTest.java new file mode 100644 index 00000000000..35f4f45f27e --- /dev/null +++ b/org.springframework.testsuite/src/test/java/org/springframework/web/filter/ShallowEtagHeaderFilterTest.java @@ -0,0 +1,93 @@ +/* + * Copyright ${YEAR} the original author or authors. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.springframework.web.filter; + +import java.io.IOException; +import javax.servlet.FilterChain; +import javax.servlet.ServletException; +import javax.servlet.ServletRequest; +import javax.servlet.ServletResponse; +import javax.servlet.http.HttpServletResponse; + +import static org.junit.Assert.*; +import org.junit.Before; +import org.junit.Test; + +import org.springframework.mock.web.MockHttpServletRequest; +import org.springframework.mock.web.MockHttpServletResponse; +import org.springframework.util.FileCopyUtils; + +public class ShallowEtagHeaderFilterTest { + + private ShallowEtagHeaderFilter filter; + + @Before + public void createFilter() throws Exception { + filter = new ShallowEtagHeaderFilter(); + } + + @Test + public void filterNoMatch() throws Exception { + final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels"); + MockHttpServletResponse response = new MockHttpServletResponse(); + + final byte[] responseBody = "Hello World".getBytes("UTF-8"); + FilterChain filterChain = new FilterChain() { + + public void doFilter(ServletRequest filterRequest, ServletResponse filterResponse) + throws IOException, ServletException { + assertEquals("Invalid request passed", request, filterRequest); + ((HttpServletResponse) filterResponse).setStatus(HttpServletResponse.SC_OK); + FileCopyUtils.copy(responseBody, filterResponse.getOutputStream()); + } + }; + + filter.doFilter(request, response, filterChain); + + assertEquals("Invalid status", 200, response.getStatus()); + assertEquals("Invalid ETag header", "\"0b10a8db164e0754105b7a99be72e3fe5\"", response.getHeader("ETag")); + assertTrue("Invalid Content-Length header", response.getContentLength() > 0); + assertArrayEquals("Invalid content", responseBody, response.getContentAsByteArray()); + } + + @Test + public void filterMatch() throws Exception { + final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels"); + String etag = "\"0b10a8db164e0754105b7a99be72e3fe5\""; + request.addHeader("If-None-Match", etag); + MockHttpServletResponse response = new MockHttpServletResponse(); + + FilterChain filterChain = new FilterChain() { + + public void doFilter(ServletRequest filterRequest, ServletResponse filterResponse) + throws IOException, ServletException { + assertEquals("Invalid request passed", request, filterRequest); + ((HttpServletResponse) filterResponse).setStatus(HttpServletResponse.SC_OK); + byte[] responseBody = "Hello World".getBytes("UTF-8"); + FileCopyUtils.copy(responseBody, filterResponse.getOutputStream()); + } + }; + + filter.doFilter(request, response, filterChain); + + assertEquals("Invalid status", 304, response.getStatus()); + assertEquals("Invalid ETag header", "\"0b10a8db164e0754105b7a99be72e3fe5\"", response.getHeader("ETag")); + assertEquals("Invalid Content-Length header", 0, response.getContentLength()); + assertArrayEquals("Invalid content", new byte[0], response.getContentAsByteArray()); + } + +} \ No newline at end of file diff --git a/org.springframework.web/src/main/java/org/springframework/web/filter/ShallowEtagHeaderFilter.java b/org.springframework.web/src/main/java/org/springframework/web/filter/ShallowEtagHeaderFilter.java new file mode 100644 index 00000000000..73989331d06 --- /dev/null +++ b/org.springframework.web/src/main/java/org/springframework/web/filter/ShallowEtagHeaderFilter.java @@ -0,0 +1,152 @@ +/* + * Copyright 2008 the original author or authors. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.springframework.web.filter; + +import java.io.ByteArrayOutputStream; +import java.io.IOException; +import java.io.OutputStreamWriter; +import java.io.PrintWriter; +import java.io.Writer; +import javax.servlet.FilterChain; +import javax.servlet.ServletException; +import javax.servlet.ServletOutputStream; +import javax.servlet.http.HttpServletRequest; +import javax.servlet.http.HttpServletResponse; +import javax.servlet.http.HttpServletResponseWrapper; + +import org.springframework.util.FileCopyUtils; +import org.springframework.util.Md5HashUtils; + +/** + * Servlet 2.3/2.4 {@link javax.servlet.Filter} that generates an ETag value based on the content on the + * response. This ETag is compared to the If-None-Match header of the request. If these headers are equal, + * the resonse content is not sent, but rather a 304 "Not Modified" status. + *

+ *

Since the ETag is based on the response content, the response (or {@link org.springframework.web.servlet.View}) + * is still rendered. As such, this filter only saves bandwith, not performance. + * + * @author Arjen Poutsma + * @since 3.0 + */ +public class ShallowEtagHeaderFilter extends OncePerRequestFilter { + + private static String HEADER_ETAG = "ETag"; + + private static String HEADER_IF_NONE_MATCH = "If-None-Match"; + + @Override + protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) + throws ServletException, IOException { + ShallowEtagResponseWrapper wrapper = new ShallowEtagResponseWrapper(response); + filterChain.doFilter(request, wrapper); + + byte[] body = wrapper.toByteArray(); + String responseETag = generateETagHeaderValue(body); + response.setHeader(HEADER_ETAG, responseETag); + + String requestETag = request.getHeader(HEADER_IF_NONE_MATCH); + if (responseETag.equals(requestETag)) { + if (logger.isTraceEnabled()) { + logger.trace("ETag [" + responseETag + "] equal to If-None-Match, sending 304"); + } + response.setStatus(HttpServletResponse.SC_NOT_MODIFIED); + } + else { + if (logger.isTraceEnabled()) { + logger.trace("ETag [" + responseETag + "] not equal to If-None-Match [" + requestETag + + "], sending normal response"); + } + response.setContentLength(body.length); + FileCopyUtils.copy(body, response.getOutputStream()); + } + } + + /** + * Generates the ETag header value from the given response body bytes array. + *

+ *

Default implementation generates an MD5 hash. + * + * @param bytes the + * @return the ETag header value + * @see Md5HashUtils + */ + protected String generateETagHeaderValue(byte[] bytes) { + StringBuilder builder = new StringBuilder("\"0"); + Md5HashUtils.appendHashString(bytes, builder); + builder.append('"'); + return builder.toString(); + } + + /** + * {@link HttpServletRequest} wrapper that buffers all content written to the {@linkplain #getOutputStream() output + * stream} and {@linkplain #getWriter() writer}, and allows this content to be retrieved via a {@link #toByteArray() + * byte array}. + */ + private static class ShallowEtagResponseWrapper extends HttpServletResponseWrapper { + + private final ByteArrayOutputStream content = new ByteArrayOutputStream(); + + private final ServletOutputStream outputStream = new ResponseServletOutputStream(); + + private PrintWriter writer; + + private ShallowEtagResponseWrapper(HttpServletResponse response) { + super(response); + } + + @Override + public ServletOutputStream getOutputStream() throws IOException { + return outputStream; + } + + @Override + public PrintWriter getWriter() throws IOException { + if (writer == null) { + String characterEncoding = getCharacterEncoding(); + Writer targetWriter = (characterEncoding != null ? + new OutputStreamWriter(outputStream, characterEncoding) : new OutputStreamWriter(outputStream)); + writer = new PrintWriter(targetWriter); + } + return writer; + } + + @Override + public void resetBuffer() { + content.reset(); + } + + @Override + public void reset() { + super.reset(); + resetBuffer(); + } + + private byte[] toByteArray() { + return content.toByteArray(); + } + + private class ResponseServletOutputStream extends ServletOutputStream { + + @Override + public void write(int b) throws IOException { + content.write(b); + } + + } + } + +}