579 lines
23 KiB
Java
579 lines
23 KiB
Java
/*
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* net/balusc/webapp/FileServlet.java
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*
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* Copyright (C) 2009 BalusC
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*
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* This program is free software: you can redistribute it and/or modify it under the terms of the
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* GNU Lesser General Public License as published by the Free Software Foundation, either version 3
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* of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
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* even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License along with this library.
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.dynmap.servlet;
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import java.io.Closeable;
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import java.io.File;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.io.RandomAccessFile;
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import java.net.URLDecoder;
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import java.security.InvalidParameterException;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import java.util.zip.GZIPOutputStream;
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import javax.servlet.ServletException;
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import javax.servlet.ServletOutputStream;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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/**
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* A file servlet supporting resume of downloads and client-side caching and GZIP of text content.
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* This servlet can also be used for images, client-side caching would become more efficient.
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* This servlet can also be used for text files, GZIP would decrease network bandwidth.
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*
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* @author BalusC
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* @link http://balusc.blogspot.com/2009/02/fileservlet-supporting-resume-and.html
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*/
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@SuppressWarnings("serial")
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public class FileServlet extends HttpServlet {
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// Constants ----------------------------------------------------------------------------------
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private static final int DEFAULT_BUFFER_SIZE = 10240; // ..bytes = 10KB.
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private static final String MULTIPART_BOUNDARY = "MULTIPART_BYTERANGES";
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// Properties ---------------------------------------------------------------------------------
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private String basePath = null;
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private boolean allow_symlinks = true;
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private String[] indexFiles = new String[] {
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"index.html"
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};
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// Actions ------------------------------------------------------------------------------------
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public FileServlet() {
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}
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public FileServlet(String basePath, boolean allow_symlinks) {
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this.basePath = new File(basePath).getAbsolutePath();
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this.allow_symlinks = allow_symlinks;
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}
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/**
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* Initialize the servlet.
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* @see HttpServlet#init().
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*/
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public void init() throws ServletException {
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if (basePath == null) {
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setBasePath(new File(getServletContext().getRealPath(getInitParameter("basePath"))).getAbsolutePath());
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}
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}
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public void setBasePath(String basePath) {
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// Validate base path.
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if (basePath == null) {
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throw new InvalidParameterException("'basePath' is required.");
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} else {
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File path = new File(basePath);
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if (!path.exists()) {
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throw new InvalidParameterException("'basePath' value '"
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+ basePath + "' does actually not exist in file system.");
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} else if (!path.isDirectory()) {
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throw new InvalidParameterException("'basePath' value '"
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+ basePath + "' is actually not a directory in file system.");
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} else if (!path.canRead()) {
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throw new InvalidParameterException("'basePath' value '"
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+ basePath + "' is actually not readable in file system.");
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}
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}
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this.basePath = basePath;
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}
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/**
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* Process HEAD request. This returns the same headers as GET request, but without content.
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* @see HttpServlet#doHead(HttpServletRequest, HttpServletResponse).
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*/
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protected void doHead(HttpServletRequest request, HttpServletResponse response)
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throws ServletException, IOException
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{
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// Process request without content.
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processRequest(request, response, false);
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}
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/**
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* Process GET request.
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* @see HttpServlet#doGet(HttpServletRequest, HttpServletResponse).
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*/
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protected void doGet(HttpServletRequest request, HttpServletResponse response)
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throws ServletException, IOException
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{
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// Process request with content.
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processRequest(request, response, true);
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}
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private static String getNormalizedPath(String p) {
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p = p.replace('\\', '/');
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String[] tok = p.split("/");
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int i, j;
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for(i = 0, j = 0; i < tok.length; i++) {
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if((tok[i] == null) || (tok[i].length() == 0) || (tok[i].equals("."))) {
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tok[i] = null;
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}
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else if(tok[i].equals("..")) {
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if(j > 0) { j--; tok[j] = null; }
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tok[i] = null;
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}
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else {
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tok[j] = tok[i];
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j++;
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}
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}
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String path = "";
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for(i = 0; i < j; i++) {
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if(tok[i] != null)
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path = path + "/" + tok[i];
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}
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return path;
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}
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/**
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* Process the actual request.
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* @param request The request to be processed.
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* @param response The response to be created.
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* @param content Whether the request body should be written (GET) or not (HEAD).
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* @throws IOException If something fails at I/O level.
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*/
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private void processRequest
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(HttpServletRequest request, HttpServletResponse response, boolean content)
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throws IOException
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{
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// Validate the requested file ------------------------------------------------------------
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// Get requested file by path info.
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String requestedFile = request.getPathInfo();
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if (requestedFile != null)
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requestedFile = getNormalizedPath(requestedFile);
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// Check if file is actually supplied to the request URL.
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if (requestedFile == null) {
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// Do your thing if the file is not supplied to the request URL.
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// Throw an exception, or send 404, or show default/warning page, or just ignore it.
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response.sendError(HttpServletResponse.SC_NOT_FOUND);
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return;
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}
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// URL-decode the file name (might contain spaces and on) and prepare file object.
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File file = new File(basePath, URLDecoder.decode(requestedFile, "UTF-8"));
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String fpath = null;
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if(allow_symlinks)
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fpath = file.getAbsolutePath();
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else
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fpath = file.getCanonicalPath();
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if (!fpath.startsWith(basePath)) {
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response.sendError(HttpServletResponse.SC_NOT_FOUND);
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return;
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}
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if (file.isDirectory()) {
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File directory = file;
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for (int i = 0; i < indexFiles.length; i++) {
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file = new File(directory, indexFiles[i]);
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if (file.isFile())
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break;
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}
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}
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// Check if file actually exists in filesystem.
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if (!file.exists()) {
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// Do your thing if the file appears to be non-existing.
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// Throw an exception, or send 404, or show default/warning page, or just ignore it.
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response.sendError(HttpServletResponse.SC_NOT_FOUND);
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return;
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}
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// Prepare some variables. The ETag is an unique identifier of the file.
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String fileName = file.getName();
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long length = file.length();
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long lastModified = file.lastModified();
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String eTag = fileName + "_" + length + "_" + lastModified;
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// Validate request headers for caching ---------------------------------------------------
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// If-None-Match header should contain "*" or ETag. If so, then return 304.
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String ifNoneMatch = request.getHeader("If-None-Match");
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if (ifNoneMatch != null && matches(ifNoneMatch, eTag)) {
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response.setHeader("ETag", eTag); // Required in 304.
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response.sendError(HttpServletResponse.SC_NOT_MODIFIED);
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return;
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}
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// If-Modified-Since header should be greater than LastModified. If so, then return 304.
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// This header is ignored if any If-None-Match header is specified.
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long ifModifiedSince = request.getDateHeader("If-Modified-Since");
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if (ifNoneMatch == null && ifModifiedSince != -1 && ifModifiedSince + 1000 > lastModified) {
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response.setHeader("ETag", eTag); // Required in 304.
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response.sendError(HttpServletResponse.SC_NOT_MODIFIED);
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return;
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}
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// Validate request headers for resume ----------------------------------------------------
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// If-Match header should contain "*" or ETag. If not, then return 412.
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String ifMatch = request.getHeader("If-Match");
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if (ifMatch != null && !matches(ifMatch, eTag)) {
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response.sendError(HttpServletResponse.SC_PRECONDITION_FAILED);
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return;
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}
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// If-Unmodified-Since header should be greater than LastModified. If not, then return 412.
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long ifUnmodifiedSince = request.getDateHeader("If-Unmodified-Since");
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if (ifUnmodifiedSince != -1 && ifUnmodifiedSince + 1000 <= lastModified) {
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response.sendError(HttpServletResponse.SC_PRECONDITION_FAILED);
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return;
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}
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// Validate and process range -------------------------------------------------------------
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// Prepare some variables. The full Range represents the complete file.
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Range full = new Range(0, length - 1, length);
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List<Range> ranges = new ArrayList<Range>();
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// Validate and process Range and If-Range headers.
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String range = request.getHeader("Range");
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if (range != null) {
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// Range header should match format "bytes=n-n,n-n,n-n...". If not, then return 416.
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if (!range.matches("^bytes=\\d*-\\d*(,\\d*-\\d*)*$")) {
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response.setHeader("Content-Range", "bytes */" + length); // Required in 416.
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response.sendError(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
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return;
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}
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// If-Range header should either match ETag or be greater then LastModified. If not,
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// then return full file.
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String ifRange = request.getHeader("If-Range");
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if (ifRange != null && !ifRange.equals(eTag)) {
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try {
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long ifRangeTime = request.getDateHeader("If-Range"); // Throws IAE if invalid.
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if (ifRangeTime != -1 && ifRangeTime + 1000 < lastModified) {
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ranges.add(full);
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}
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} catch (IllegalArgumentException ignore) {
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ranges.add(full);
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}
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}
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// If any valid If-Range header, then process each part of byte range.
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if (ranges.isEmpty()) {
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String[] rangesParts = range.substring(6).split(",");
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if (rangesParts.length > 1) {
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response.setHeader("Content-Range", "bytes */" + length); // Required in 416.
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response.sendError(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
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return;
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}
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for (String part : rangesParts) {
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// Assuming a file with length of 100, the following examples returns bytes at:
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// 50-80 (50 to 80), 40- (40 to length=100), -20 (length-20=80 to length=100).
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long start = sublong(part, 0, part.indexOf("-"));
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long end = sublong(part, part.indexOf("-") + 1, part.length());
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if (start == -1) {
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start = length - end;
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end = length - 1;
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} else if (end == -1 || end > length - 1) {
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end = length - 1;
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}
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// Check if Range is syntactically valid. If not, then return 416.
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if (start > end) {
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response.setHeader("Content-Range", "bytes */" + length); // Required in 416.
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response.sendError(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
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return;
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}
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// Add range.
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ranges.add(new Range(start, end, length));
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}
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}
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}
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// Prepare and initialize response --------------------------------------------------------
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// Get content type by file name and set default GZIP support and content disposition.
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boolean acceptsGzip = false;
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String disposition = "inline";
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String contentType = getContentType(fileName);
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// If content type is text, then determine whether GZIP content encoding is supported by
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// the browser and expand content type with the one and right character encoding.
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if (contentType.startsWith("text")) {
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String acceptEncoding = request.getHeader("Accept-Encoding");
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acceptsGzip = acceptEncoding != null && accepts(acceptEncoding, "gzip");
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contentType += ";charset=UTF-8";
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}
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// Else, expect for images, determine content disposition. If content type is supported by
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// the browser, then set to inline, else attachment which will pop a 'save as' dialogue.
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else if (!contentType.startsWith("image")) {
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String accept = request.getHeader("Accept");
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disposition = accept != null && accepts(accept, contentType) ? "inline" : "attachment";
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}
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// Initialize response.
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response.reset();
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response.setBufferSize(DEFAULT_BUFFER_SIZE);
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response.setHeader("Content-Disposition", disposition + ";filename=\"" + fileName + "\"");
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response.setHeader("Accept-Ranges", "bytes");
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response.setHeader("ETag", eTag);
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response.setDateHeader("Last-Modified", lastModified);
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// Send requested file (part(s)) to client ------------------------------------------------
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// Prepare streams.
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RandomAccessFile input = null;
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OutputStream output = null;
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try {
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// Open streams.
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input = new RandomAccessFile(file, "r");
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output = response.getOutputStream();
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if (ranges.isEmpty() || ranges.get(0) == full) {
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// Return full file.
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Range r = full;
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response.setContentType(contentType);
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response.setHeader("Content-Range", "bytes " + r.start + "-" + r.end + "/" + r.total);
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if (content) {
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if (acceptsGzip) {
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// The browser accepts GZIP, so GZIP the content.
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response.setHeader("Content-Encoding", "gzip");
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output = new GZIPOutputStream(output, DEFAULT_BUFFER_SIZE);
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} else {
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// Content length is not directly predictable in case of GZIP.
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// So only add it if there is no means of GZIP, else browser will hang.
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response.setHeader("Content-Length", String.valueOf(r.length));
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}
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// Copy full range.
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copy(input, output, r.start, r.length);
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}
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} else if (ranges.size() == 1) {
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// Return single part of file.
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Range r = ranges.get(0);
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response.setContentType(contentType);
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response.setHeader("Content-Range", "bytes " + r.start + "-" + r.end + "/" + r.total);
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response.setHeader("Content-Length", String.valueOf(r.length));
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response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT); // 206.
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if (content) {
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// Copy single part range.
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copy(input, output, r.start, r.length);
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}
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} else {
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// Return multiple parts of file.
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response.setContentType("multipart/byteranges; boundary=" + MULTIPART_BOUNDARY);
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response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT); // 206.
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if (content) {
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// Cast back to ServletOutputStream to get the easy println methods.
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ServletOutputStream sos = (ServletOutputStream) output;
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// Copy multi part range.
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for (Range r : ranges) {
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// Add multipart boundary and header fields for every range.
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sos.println();
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sos.println("--" + MULTIPART_BOUNDARY);
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sos.println("Content-Type: " + contentType);
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sos.println("Content-Range: bytes " + r.start + "-" + r.end + "/" + r.total);
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// Copy single part range of multi part range.
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copy(input, output, r.start, r.length);
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}
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// End with multipart boundary.
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sos.println();
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sos.println("--" + MULTIPART_BOUNDARY + "--");
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}
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}
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} finally {
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// Gently close streams.
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close(output);
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close(input);
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}
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}
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// Helpers (can be refactored to public utility class) ----------------------------------------
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final static Map<String, String> mimeTypes = new HashMap<String, String>() {{
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this.put(".html", "text/html");
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this.put(".htm", "text/html");
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this.put(".js", "text/javascript");
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this.put(".png", "image/png");
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this.put(".jpg", "image/jpeg");
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this.put(".css", "text/css");
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this.put(".txt", "text/plain");
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}};
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public String getContentType(String fileName) {
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// Don't use getServetContext!
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/*String contentType = getServletContext().getMimeType(fileName);
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*/
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String contentType = null;
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int i = fileName.lastIndexOf('.');
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if (i >= 0) {
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String extension = fileName.substring(i);
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contentType = mimeTypes.get(extension);
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}
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if (contentType == null) {
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contentType = "application/octet-stream";
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}
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return contentType;
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}
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/**
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* Returns true if the given accept header accepts the given value.
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* @param acceptHeader The accept header.
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* @param toAccept The value to be accepted.
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* @return True if the given accept header accepts the given value.
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*/
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private static boolean accepts(String acceptHeader, String toAccept) {
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String[] acceptValues = acceptHeader.split("\\s*(,|;)\\s*");
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Arrays.sort(acceptValues);
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return Arrays.binarySearch(acceptValues, toAccept) > -1
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|| Arrays.binarySearch(acceptValues, toAccept.replaceAll("/.*$", "/*")) > -1
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|| Arrays.binarySearch(acceptValues, "*/*") > -1;
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}
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/**
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* Returns true if the given match header matches the given value.
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* @param matchHeader The match header.
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* @param toMatch The value to be matched.
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* @return True if the given match header matches the given value.
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*/
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private static boolean matches(String matchHeader, String toMatch) {
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String[] matchValues = matchHeader.split("\\s*,\\s*");
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Arrays.sort(matchValues);
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return Arrays.binarySearch(matchValues, toMatch) > -1
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|| Arrays.binarySearch(matchValues, "*") > -1;
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}
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/**
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* Returns a substring of the given string value from the given begin index to the given end
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* index as a long. If the substring is empty, then -1 will be returned
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* @param value The string value to return a substring as long for.
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* @param beginIndex The begin index of the substring to be returned as long.
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* @param endIndex The end index of the substring to be returned as long.
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* @return A substring of the given string value as long or -1 if substring is empty.
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*/
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private static long sublong(String value, int beginIndex, int endIndex) {
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String substring = value.substring(beginIndex, endIndex);
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return (substring.length() > 0) ? Long.parseLong(substring) : -1;
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}
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|
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/**
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* Copy the given byte range of the given input to the given output.
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|
* @param input The input to copy the given range to the given output for.
|
|
* @param output The output to copy the given range from the given input for.
|
|
* @param start Start of the byte range.
|
|
* @param length Length of the byte range.
|
|
* @throws IOException If something fails at I/O level.
|
|
*/
|
|
private static void copy(RandomAccessFile input, OutputStream output, long start, long length)
|
|
throws IOException
|
|
{
|
|
byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
|
|
int read;
|
|
|
|
if (input.length() == length) {
|
|
// Write full range.
|
|
while ((read = input.read(buffer)) > 0) {
|
|
output.write(buffer, 0, read);
|
|
}
|
|
} else {
|
|
// Write partial range.
|
|
input.seek(start);
|
|
long toRead = length;
|
|
|
|
while ((read = input.read(buffer)) > 0) {
|
|
if ((toRead -= read) > 0) {
|
|
output.write(buffer, 0, read);
|
|
} else {
|
|
output.write(buffer, 0, (int) toRead + read);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Close the given resource.
|
|
* @param resource The resource to be closed.
|
|
*/
|
|
private static void close(Closeable resource) {
|
|
if (resource != null) {
|
|
try {
|
|
resource.close();
|
|
} catch (IOException ignore) {
|
|
// Ignore IOException. If you want to handle this anyway, it might be useful to know
|
|
// that this will generally only be thrown when the client aborted the request.
|
|
}
|
|
}
|
|
}
|
|
|
|
// Inner classes ------------------------------------------------------------------------------
|
|
|
|
/**
|
|
* This class represents a byte range.
|
|
*/
|
|
protected class Range {
|
|
long start;
|
|
long end;
|
|
long length;
|
|
long total;
|
|
|
|
/**
|
|
* Construct a byte range.
|
|
* @param start Start of the byte range.
|
|
* @param end End of the byte range.
|
|
* @param total Total length of the byte source.
|
|
*/
|
|
public Range(long start, long end, long total) {
|
|
this.start = start;
|
|
this.end = end;
|
|
this.length = end - start + 1;
|
|
this.total = total;
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|