SPR-4419: Shallow ETag support
git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@207 50f2f4bb-b051-0410-bef5-90022cba6387
This commit is contained in:
Arjen Poutsma
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862e5c35f7
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/*
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* Copyright ${YEAR} the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.web.filter;
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import java.io.IOException;
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import javax.servlet.FilterChain;
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import javax.servlet.ServletException;
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import javax.servlet.ServletRequest;
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import javax.servlet.ServletResponse;
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import javax.servlet.http.HttpServletResponse;
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import static org.junit.Assert.*;
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import org.junit.Before;
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import org.junit.Test;
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import org.springframework.mock.web.MockHttpServletRequest;
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import org.springframework.mock.web.MockHttpServletResponse;
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import org.springframework.util.FileCopyUtils;
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public class ShallowEtagHeaderFilterTest {
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private ShallowEtagHeaderFilter filter;
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@Before
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public void createFilter() throws Exception {
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filter = new ShallowEtagHeaderFilter();
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}
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@Test
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public void filterNoMatch() throws Exception {
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final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
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MockHttpServletResponse response = new MockHttpServletResponse();
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final byte[] responseBody = "Hello World".getBytes("UTF-8");
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FilterChain filterChain = new FilterChain() {
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public void doFilter(ServletRequest filterRequest, ServletResponse filterResponse)
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throws IOException, ServletException {
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assertEquals("Invalid request passed", request, filterRequest);
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((HttpServletResponse) filterResponse).setStatus(HttpServletResponse.SC_OK);
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FileCopyUtils.copy(responseBody, filterResponse.getOutputStream());
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}
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};
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filter.doFilter(request, response, filterChain);
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assertEquals("Invalid status", 200, response.getStatus());
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assertEquals("Invalid ETag header", "\"0b10a8db164e0754105b7a99be72e3fe5\"", response.getHeader("ETag"));
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assertTrue("Invalid Content-Length header", response.getContentLength() > 0);
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assertArrayEquals("Invalid content", responseBody, response.getContentAsByteArray());
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}
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@Test
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public void filterMatch() throws Exception {
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final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
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String etag = "\"0b10a8db164e0754105b7a99be72e3fe5\"";
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request.addHeader("If-None-Match", etag);
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MockHttpServletResponse response = new MockHttpServletResponse();
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FilterChain filterChain = new FilterChain() {
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public void doFilter(ServletRequest filterRequest, ServletResponse filterResponse)
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throws IOException, ServletException {
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assertEquals("Invalid request passed", request, filterRequest);
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((HttpServletResponse) filterResponse).setStatus(HttpServletResponse.SC_OK);
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byte[] responseBody = "Hello World".getBytes("UTF-8");
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FileCopyUtils.copy(responseBody, filterResponse.getOutputStream());
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}
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};
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filter.doFilter(request, response, filterChain);
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assertEquals("Invalid status", 304, response.getStatus());
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assertEquals("Invalid ETag header", "\"0b10a8db164e0754105b7a99be72e3fe5\"", response.getHeader("ETag"));
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assertEquals("Invalid Content-Length header", 0, response.getContentLength());
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assertArrayEquals("Invalid content", new byte[0], response.getContentAsByteArray());
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}
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}
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@ -0,0 +1,152 @@
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/*
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* Copyright 2008 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.web.filter;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.OutputStreamWriter;
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import java.io.PrintWriter;
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import java.io.Writer;
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import javax.servlet.FilterChain;
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import javax.servlet.ServletException;
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import javax.servlet.ServletOutputStream;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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import javax.servlet.http.HttpServletResponseWrapper;
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import org.springframework.util.FileCopyUtils;
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import org.springframework.util.Md5HashUtils;
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/**
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* Servlet 2.3/2.4 {@link javax.servlet.Filter} that generates an <code>ETag</code> value based on the content on the
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* response. This ETag is compared to the <code>If-None-Match</code> header of the request. If these headers are equal,
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* the resonse content is not sent, but rather a 304 "Not Modified" status.
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* <p/>
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* <p/>Since the ETag is based on the response content, the response (or {@link org.springframework.web.servlet.View})
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* is still rendered. As such, this filter only saves bandwith, not performance.
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*
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* @author Arjen Poutsma
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* @since 3.0
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*/
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public class ShallowEtagHeaderFilter extends OncePerRequestFilter {
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private static String HEADER_ETAG = "ETag";
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private static String HEADER_IF_NONE_MATCH = "If-None-Match";
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@Override
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protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
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throws ServletException, IOException {
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ShallowEtagResponseWrapper wrapper = new ShallowEtagResponseWrapper(response);
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filterChain.doFilter(request, wrapper);
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byte[] body = wrapper.toByteArray();
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String responseETag = generateETagHeaderValue(body);
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response.setHeader(HEADER_ETAG, responseETag);
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String requestETag = request.getHeader(HEADER_IF_NONE_MATCH);
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if (responseETag.equals(requestETag)) {
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if (logger.isTraceEnabled()) {
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logger.trace("ETag [" + responseETag + "] equal to If-None-Match, sending 304");
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}
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response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
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}
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else {
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if (logger.isTraceEnabled()) {
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logger.trace("ETag [" + responseETag + "] not equal to If-None-Match [" + requestETag +
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"], sending normal response");
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}
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response.setContentLength(body.length);
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FileCopyUtils.copy(body, response.getOutputStream());
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}
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}
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/**
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* Generates the ETag header value from the given response body bytes array.
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* <p/>
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* <p/>Default implementation generates an MD5 hash.
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*
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* @param bytes the
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* @return the ETag header value
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* @see Md5HashUtils
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*/
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protected String generateETagHeaderValue(byte[] bytes) {
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StringBuilder builder = new StringBuilder("\"0");
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Md5HashUtils.appendHashString(bytes, builder);
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builder.append('"');
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return builder.toString();
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}
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/**
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* {@link HttpServletRequest} wrapper that buffers all content written to the {@linkplain #getOutputStream() output
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* stream} and {@linkplain #getWriter() writer}, and allows this content to be retrieved via a {@link #toByteArray()
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* byte array}.
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*/
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private static class ShallowEtagResponseWrapper extends HttpServletResponseWrapper {
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private final ByteArrayOutputStream content = new ByteArrayOutputStream();
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private final ServletOutputStream outputStream = new ResponseServletOutputStream();
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private PrintWriter writer;
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private ShallowEtagResponseWrapper(HttpServletResponse response) {
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super(response);
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}
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@Override
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public ServletOutputStream getOutputStream() throws IOException {
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return outputStream;
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}
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@Override
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public PrintWriter getWriter() throws IOException {
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if (writer == null) {
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String characterEncoding = getCharacterEncoding();
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Writer targetWriter = (characterEncoding != null ?
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new OutputStreamWriter(outputStream, characterEncoding) : new OutputStreamWriter(outputStream));
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writer = new PrintWriter(targetWriter);
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}
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return writer;
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}
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@Override
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public void resetBuffer() {
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content.reset();
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}
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@Override
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public void reset() {
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super.reset();
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resetBuffer();
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}
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private byte[] toByteArray() {
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return content.toByteArray();
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}
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private class ResponseServletOutputStream extends ServletOutputStream {
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@Override
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public void write(int b) throws IOException {
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content.write(b);
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}
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}
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}
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}
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