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feat: compress response if service wants to (#1728)
* initial commit, compress response if service wants to Signed-off-by: achmelo <a.chmelo@gmail.com> * add unit tests Signed-off-by: achmelo <a.chmelo@gmail.com> * empty gzip body should be 20 bytes Signed-off-by: achmelo <a.chmelo@gmail.com> * test flush buffers Signed-off-by: achmelo <a.chmelo@gmail.com> * test no instances available and close buffers Signed-off-by: achmelo <a.chmelo@gmail.com> * compress per service acceptance test Signed-off-by: achmelo <a.chmelo@gmail.com> * compress per service acceptance test Signed-off-by: achmelo <a.chmelo@gmail.com> * resolve conflicts Signed-off-by: achmelo <a.chmelo@gmail.com> * provide description for filter class Signed-off-by: achmelo <a.chmelo@gmail.com>
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‎apiml-tomcat-common/src/main/java/org/zowe/apiml/gzip/GZipResponseException.java‎

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/*
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* This program and the accompanying materials are made available under the terms of the
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* Eclipse Public License v2.0 which accompanies this distribution, and is available at
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* https://www.eclipse.org/legal/epl-v20.html
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*
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* SPDX-License-Identifier: EPL-2.0
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*
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* Copyright Contributors to the Zowe Project.
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*/
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package org.zowe.apiml.gzip;
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public class GZipResponseException extends RuntimeException {
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public GZipResponseException(String message) {
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super(message);
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}
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}

‎apiml-tomcat-common/src/main/java/org/zowe/apiml/gzip/GZipResponseUtils.java‎

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/*
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* This program and the accompanying materials are made available under the terms of the
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* Eclipse Public License v2.0 which accompanies this distribution, and is available at
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* https://www.eclipse.org/legal/epl-v20.html
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*
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* SPDX-License-Identifier: EPL-2.0
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*
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* Copyright Contributors to the Zowe Project.
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*/
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package org.zowe.apiml.gzip;
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import javax.servlet.http.HttpServletResponse;
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public final class GZipResponseUtils {
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/**
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* Gzipping an empty file or stream always results in a 20 byte output
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* This is in java or elsewhere.
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* <p/>
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* On a unix system to reproduce do <code>gzip -n empty_file</code>. -n tells gzip to not
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* include the file name. The resulting file size is 20 bytes.
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* <p/>
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* Therefore 20 bytes can be used indicate that the gzip byte[] will be empty when ungzipped.
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*/
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private static final int EMPTY_GZIPPED_CONTENT_SIZE = 20;
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/**
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* Utility class. No public constructor.
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*/
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private GZipResponseUtils() {
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}
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/**
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* Checks whether a gzipped body is actually empty and should just be zero.
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* When the compressedBytes is {@link #EMPTY_GZIPPED_CONTENT_SIZE} it should be zero.
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*
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* @param compressedBytes the gzipped response body
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* @return true if the response should be 0, even if it is isn't.
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*/
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public static boolean shouldGzippedBodyBeZero(byte[] compressedBytes) {
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return compressedBytes.length == EMPTY_GZIPPED_CONTENT_SIZE;
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}
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/**
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* Performs a number of checks to ensure response saneness according to the rules of RFC2616:
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* <ol>
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* <li>If the response code is {@link javax.servlet.http.HttpServletResponse#SC_NO_CONTENT} then it is forbidden for the body
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* to contain anything. See http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.2.5
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* <li>If the response code is {@link javax.servlet.http.HttpServletResponse#SC_NOT_MODIFIED} then it is forbidden for the body
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* to contain anything. See http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.5
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* </ol>
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*
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* @param responseStatus the responseStatus
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* @return true if the response should be 0, even if it is isn't.
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*/
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public static boolean shouldBodyBeZero(int responseStatus) {
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return responseStatus == HttpServletResponse.SC_NO_CONTENT || responseStatus == HttpServletResponse.SC_NOT_MODIFIED;
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}
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/**
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* Adds the gzip HTTP header to the response.
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* <p/>
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* <p>
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* This is need when a gzipped body is returned so that browsers can properly decompress it.
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* </p>
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*
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* @param response the response which will have a header added to it. I.e this method changes its parameter
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* @throws RuntimeException Either the response is committed or we were called using the include method
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* from a {@link javax.servlet.RequestDispatcher#include(javax.servlet.ServletRequest, javax.servlet.ServletResponse)}
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* method and the set header is ignored.
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*/
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public static void addGzipHeader(final HttpServletResponse response) throws GZipResponseException {
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response.setHeader("Content-Encoding", "gzip");
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boolean containsEncoding = response.containsHeader("Content-Encoding");
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if (!containsEncoding) {
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throw new GZipResponseException("Failure when attempting to set "
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+ "Content-Encoding: gzip");
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}
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}
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}

‎apiml-tomcat-common/src/main/java/org/zowe/apiml/gzip/GZipResponseWrapper.java‎

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/*
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* This program and the accompanying materials are made available under the terms of the
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* Eclipse Public License v2.0 which accompanies this distribution, and is available at
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* https://www.eclipse.org/legal/epl-v20.html
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*
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* SPDX-License-Identifier: EPL-2.0
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*
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* Copyright Contributors to the Zowe Project.
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*/
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package org.zowe.apiml.gzip;
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import javax.servlet.ServletOutputStream;
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import javax.servlet.http.HttpServletResponse;
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import javax.servlet.http.HttpServletResponseWrapper;
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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.util.zip.GZIPOutputStream;
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public class GZipResponseWrapper extends HttpServletResponseWrapper {
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private GZipServletOutputStream gzipOutputStream;
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private PrintWriter printWriter = null;
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private boolean disableFlushBuffer = false;
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/**
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* Constructs a response adaptor wrapping the given response.
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*
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* @param response The response to be wrapped
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* @throws IllegalArgumentException if the response is null
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*/
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public GZipResponseWrapper(HttpServletResponse response, GZIPOutputStream stream) {
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super(response);
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gzipOutputStream = new GZipServletOutputStream(stream);
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}
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public void close() throws IOException {
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if (this.printWriter != null) {
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this.printWriter.close();
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}
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if (this.gzipOutputStream != null) {
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this.gzipOutputStream.close();
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}
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}
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/**
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* Flush OutputStream or PrintWriter
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*
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* @throws IOException
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*/
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@Override
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public void flushBuffer() throws IOException {
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flush();
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// doing this might leads to response already committed exception
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// when the PageInfo has not yet built but the buffer already flushed
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// Happens in Weblogic when a servlet forward to a JSP page and the forward
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// method trigger a flush before it forwarded to the JSP
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// disableFlushBuffer for that purpose is 'true' by default
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if (!disableFlushBuffer) {
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super.flushBuffer();
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}
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}
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/**
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* Flushes all the streams for this response.
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*/
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public void flush() throws IOException {
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if (printWriter != null) {
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printWriter.flush();
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}
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if (gzipOutputStream != null) {
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gzipOutputStream.flush();
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}
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}
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@Override
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public ServletOutputStream getOutputStream() {
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if (this.printWriter != null) {
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throw new IllegalStateException(
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"PrintWriter obtained already - cannot get OutputStream");
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}
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return this.gzipOutputStream;
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}
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@Override
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public PrintWriter getWriter() throws IOException {
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if (this.printWriter == null) {
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this.gzipOutputStream = new GZipServletOutputStream(
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getResponse().getOutputStream());
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this.printWriter = new PrintWriter(new OutputStreamWriter(
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this.gzipOutputStream, getResponse().getCharacterEncoding()), true);
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}
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return this.printWriter;
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}
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@Override
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public void setContentLength(int length) {
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//ignore, since content length of zipped content
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//does not match content length of unzipped content.
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}
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/**
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* Set if the wrapped reponse's buffer flushing should be disabled.
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*
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* @param disableFlushBuffer true if the wrapped reponse's buffer flushing should be disabled
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*/
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public void setDisableFlushBuffer(boolean disableFlushBuffer) {
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this.disableFlushBuffer = disableFlushBuffer;
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}
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}

‎apiml-tomcat-common/src/main/java/org/zowe/apiml/gzip/GZipServletOutputStream.java‎

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/*
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* This program and the accompanying materials are made available under the terms of the
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* Eclipse Public License v2.0 which accompanies this distribution, and is available at
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* https://www.eclipse.org/legal/epl-v20.html
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*
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* SPDX-License-Identifier: EPL-2.0
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*
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* Copyright Contributors to the Zowe Project.
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*/
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package org.zowe.apiml.gzip;
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import javax.servlet.ServletOutputStream;
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import javax.servlet.WriteListener;
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import java.io.IOException;
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import java.io.OutputStream;
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public class GZipServletOutputStream extends ServletOutputStream {
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private OutputStream gzipOutputStream;
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public GZipServletOutputStream(OutputStream outputStream) {
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super();
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this.gzipOutputStream = outputStream;
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}
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@Override
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public void close() throws IOException {
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this.gzipOutputStream.close();
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}
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@Override
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public void flush() throws IOException {
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this.gzipOutputStream.flush();
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}
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@Override
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public void write(byte[] b) throws IOException {
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this.gzipOutputStream.write(b);
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}
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@Override
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public void write(byte[] b, int off, int len) throws IOException {
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this.gzipOutputStream.write(b, off, len);
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}
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@Override
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public void write(int b) throws IOException {
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this.gzipOutputStream.write(b);
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}
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@Override
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public boolean isReady() {
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return true;
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}
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@Override
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public void setWriteListener(WriteListener listener) {
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// writer is never used in this case
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}
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}

‎apiml-tomcat-common/src/test/java/org/zowe/apiml/gzip/GZipResponseUtilsTest.java‎

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/*
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* This program and the accompanying materials are made available under the terms of the
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* Eclipse Public License v2.0 which accompanies this distribution, and is available at
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* https://www.eclipse.org/legal/epl-v20.html
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*
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* SPDX-License-Identifier: EPL-2.0
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*
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* Copyright Contributors to the Zowe Project.
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*/
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package org.zowe.apiml.gzip;
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import org.junit.jupiter.api.Test;
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import org.springframework.mock.web.MockHttpServletResponse;
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import javax.servlet.http.HttpServletResponse;
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import static org.junit.jupiter.api.Assertions.*;
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import static org.mockito.Mockito.mock;
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import static org.mockito.Mockito.when;
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class GZipResponseUtilsTest {
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@Test
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void addHeader() {
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MockHttpServletResponse response = new MockHttpServletResponse();
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GZipResponseUtils.addGzipHeader(response);
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assertEquals("gzip", response.getHeader("Content-Encoding"));
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}
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@Test
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void whenSetHeaderFails_thenThrowException() {
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HttpServletResponse response = mock(HttpServletResponse.class);
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when(response.containsHeader("Content-Encoding")).thenReturn(false);
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assertThrows(GZipResponseException.class, () -> GZipResponseUtils.addGzipHeader(response));
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}
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@Test
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void whenContentShouldBeEmpty_thenReturnTrue() {
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assertFalse(GZipResponseUtils.shouldBodyBeZero(200));
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assertTrue(GZipResponseUtils.shouldBodyBeZero(204));
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assertTrue(GZipResponseUtils.shouldBodyBeZero(304));
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}
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@Test
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void whenGZippedBodyIsEmpty_thenReturnTrue() {
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byte[] bytes = new byte[20];
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assertTrue(GZipResponseUtils.shouldGzippedBodyBeZero(bytes));
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}
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}

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