GZIP Http Servlet Response
好久没贴过代码了,心血来潮。
/* * Copyright (c) 2009, 2010, B3log Team * * 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.b3log.latke.servlet.filter; import java.io.IOException; import java.io.OutputStreamWriter; import java.io.PrintWriter; import java.util.logging.Level; import java.util.logging.Logger; import java.util.zip.GZIPOutputStream; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpServletResponseWrapper; /** * Abstract HTTP response GZIP filter. * * @author Liang Ding * @version 1.0.0.1, Dec 16, 2010 */ public abstract class AbstractGZIPFilter implements Filter { /** * Logger. */ private static final Logger LOGGER = Logger.getLogger(AbstractGZIPFilter.class.getName()); @Override public void init(final FilterConfig cfg) throws ServletException { } /** * Wraps the http servlet response with GZIP if could. * * @param request the specified request * @param response the specified response * @param chain filter chain * @throws IOException io exception * @throws ServletException servlet exception */ @Override public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain) throws IOException, ServletException { final HttpServletRequest httpServletRequest = (HttpServletRequest) request; final String requestURI = httpServletRequest.getRequestURI(); if (shouldSkip(requestURI)) { LOGGER.log(Level.FINEST, "Skip GZIP filter request[URI={0}]", requestURI); chain.doFilter(request, response); return; } final String acceptEncoding = httpServletRequest.getHeader("Accept-Encoding"); boolean supportGZIP = false; if (null != acceptEncoding && 0 <= acceptEncoding.indexOf("gzip")) { supportGZIP = true; } if (!supportGZIP) { LOGGER.info("Gzip NOT be supported"); chain.doFilter(request, response); return; } final HttpServletResponse httpServletResponse = (HttpServletResponse) response; httpServletResponse.addHeader("Content-Encoding", "gzip"); httpServletResponse.addHeader("Vary", "Accept-Encoding"); chain.doFilter(request, new GZIPServletResponseWrapper(httpServletResponse)); } /** * Determines whether the specified request URI should be skipped filter. * ** Note: This method SHOULD be invoked for all filters with pattern * "/*". *
* * @param requestURI the specified request URI * @return {@code true} if should be skipped, {@code false} otherwise */ public abstract boolean shouldSkip(final String requestURI); @Override public void destroy() { } /** * HTTP response wrapper for GZIP. * * @author Liang Ding * @version 1.0.0.0, Dec 16, 2010 */ private class GZIPServletResponseWrapper extends HttpServletResponseWrapper { /** * GZIP output stream. */ private GZIPOutputStream gzipStream; /** * Servlet output stream. */ private ServletOutputStream servletOutputStream; /** * Print writer. */ private PrintWriter printWriter; /** * Constructs an {@link GZIPServletResponseWrapper} object with the * specified http servlet response. * * @param httpServletResponse the specified http servlet response * @throws IOException io exception */ GZIPServletResponseWrapper(final HttpServletResponse httpServletResponse) throws IOException { super(httpServletResponse); } @Override public ServletOutputStream getOutputStream() throws IOException { if (null == servletOutputStream) { servletOutputStream = createOutputStream(); } return servletOutputStream; } @Override public PrintWriter getWriter() throws IOException { if (null == printWriter) { printWriter = new PrintWriter( new OutputStreamWriter(getOutputStream(), getCharacterEncoding())); } return printWriter; } /** * Creates output stream with GZIP delegation. * * @return servlet output stream * @throws IOException io exception */ private ServletOutputStream createOutputStream() throws IOException { final ServletResponse servletResponse = this.getResponse(); gzipStream = new GZIPOutputStream(servletResponse.getOutputStream()); return new ServletOutputStream() { @Override public void write(final int b) throws IOException { gzipStream.write(b); } @Override public void flush() throws IOException { gzipStream.flush(); } @Override public void close() throws IOException { gzipStream.close(); } /* * These two are not absolutely needed. They are here simply * because they were overriden by GZIPOutputStream. */ @Override public void write(final byte[] b) throws IOException { gzipStream.write(b); } @Override public void write(final byte[] b, final int off, final int len) throws IOException { gzipStream.write(b, off, len); } }; } } }
本文是使用 B3log Solo 从 简约设计の艺术 进行同步发布的