com.idrsolutions.microservice.utils.DefaultFileServlet Maven / Gradle / Ivy
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/*
* Copyright 2023 IDRsolutions
* Copyright 2021 OmniFaces
*
* 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
*
* https://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 com.idrsolutions.microservice.utils;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.nio.file.Files;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.TimeUnit;
import java.util.logging.Logger;
import java.util.regex.Pattern;
import static java.lang.String.format;
import static java.nio.charset.StandardCharsets.UTF_8;
import static java.util.concurrent.TimeUnit.SECONDS;
import static java.util.logging.Level.FINE;
/**
*
* The well known "BalusC FileServlet",
* as an abstract template, slightly refactored, rewritten and modernized with a.o. fast NIO stuff instead of legacy
* RandomAccessFile. GZIP support is stripped off as that can be done application wide via GzipResponseFilter.
*
* This servlet properly deals with ETag, If-None-Match and If-Modified-Since
* caching requests, hereby improving browser caching. This servlet also properly deals with Range and
* If-Range ranging requests (RFC7233), which is required
* by most media players for proper audio/video streaming, and by webbrowsers and for a proper resume of an paused
* download, and by download accelerators to be able to request smaller parts simultaneously. This servlet is ideal when
* you have large files like media files placed outside the web application and you can't use the default servlet.
*
*
Usage
*
* Just extend this class and override the {@link #getFile(HttpServletRequest)} method to return the desired file. If
* you want to trigger a HTTP 400 "Bad Request" error, simply throw {@link IllegalArgumentException}. If you want to
* trigger a HTTP 404 "Not Found" error, simply return null, or a non-existent file.
*
* Here's a concrete example which serves it via an URL like /media/foo.ext:
*
*
* @WebServlet("/media/*")
* public class MediaFileServlet extends DefaultFileServlet {
*
* private File folder;
*
* @Override
* public void init() throws ServletException {
* folder = new File("/var/webapp/media");
* }
*
* @Override
* protected File getFile(HttpServletRequest request) {
* String pathInfo = request.getPathInfo();
*
* if (pathInfo == null || pathInfo.isEmpty() || "/".equals(pathInfo)) {
* throw new IllegalArgumentException();
* }
*
* return new File(folder, pathInfo);
* }
*
* }
*
*
* You can embed it in e.g. HTML5 video tag as below:
*
* <video src="#{request.contextPath}/media/video.mp4" controls="controls" />
*
*
* Customizing DefaultFileServlet
*
* If more fine grained control is desired for handling "file not found" error, determining the cache expire time, the
* content type, whether the file should be supplied as an attachment and the attachment's file name, then the developer
* can opt to override one or more of the following protected methods:
*
* - {@link #handleFileNotFound(HttpServletRequest, HttpServletResponse)}
*
- {@link #getExpireTime(HttpServletRequest, File)}
*
- {@link #getContentType(HttpServletRequest, File)}
*
- {@link #isAttachment(HttpServletRequest, String)}
*
- {@link #getAttachmentName(HttpServletRequest, File)}
*
*
* See also:
*
* - How to stream audio/video files such as MP3, MP4, AVI, etc using a Servlet
*
- Abstract template for a static resource servlet
*
*
* This class is a derivative of the OmniFaces FileServlet class.
*
* Modifications made in this version:
*
* - Inlined imported omnifaces dependencies to make this class fully self-contained
*
- Changed package and class name so as not to conflict if used in other projects that include their own version
*
- Added a new abstract method {@link #getBasePath()} which defines the location on disk from which to serve files
*
- Added a default implementation of {@link #getFile(HttpServletRequest)} which calls {@link #getBasePath()}
*
- Updated ByteBuffer usage in {@link #stream(InputStream, OutputStream)} and {@link #stream(File, OutputStream, long, long)}
* to ensure code functions on Java 8 when compiled with a Java version higher than 9
*
- Moved WritableByteChannel into a try-with-resources statement for {@link #stream(File, OutputStream, long, long)}
*
*
* @author Bauke Scholtz
* @since 2.2
*/
public abstract class DefaultFileServlet extends HttpServlet {
// Constants ------------------------------------------------------------------------------------------------------
private static final long serialVersionUID = 1L;
private static final Logger logger = Logger.getLogger(DefaultFileServlet.class.getName());
private static final Long DEFAULT_EXPIRE_TIME_IN_SECONDS = TimeUnit.DAYS.toSeconds(30);
private static final long ONE_SECOND_IN_MILLIS = SECONDS.toMillis(1);
private static final String ETAG = "W/\"%s-%s\"";
private static final Pattern RANGE_PATTERN = Pattern.compile("^bytes=[0-9]*-[0-9]*(,[0-9]*-[0-9]*)*+$");
private static final String MULTIPART_BOUNDARY = UUID.randomUUID().toString();
// Actions --------------------------------------------------------------------------------------------------------
@Override
protected void doHead(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doRequest(request, response, true);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doRequest(request, response, false);
}
private void doRequest(HttpServletRequest request, HttpServletResponse response, boolean head) throws IOException {
response.reset();
Resource resource;
try {
resource = new Resource(getFile(request));
}
catch (IllegalArgumentException e) {
logger.log(FINE, "Got an IllegalArgumentException from user code; interpreting it as 400 Bad Request.", e);
response.sendError(HttpServletResponse.SC_BAD_REQUEST);
return;
}
if (resource.file == null) {
handleFileNotFound(request, response);
return;
}
if (preconditionFailed(request, resource)) {
response.sendError(HttpServletResponse.SC_PRECONDITION_FAILED);
return;
}
setCacheHeaders(response, resource, getExpireTime(request, resource.file));
if (notModified(request, resource)) {
response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
return;
}
List ranges = getRanges(request, resource);
if (ranges == null) {
response.setHeader("Content-Range", "bytes */" + resource.length);
response.sendError(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
return;
}
if (!ranges.isEmpty()) {
response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
}
else {
ranges.add(new Range(0, resource.length - 1)); // Full content.
}
String contentType = setContentHeaders(request, response, resource, ranges);
if (head) {
return;
}
writeContent(response, resource, ranges, contentType);
}
/**
* Returns the directory on disk from which to serve files.
* If empty string is provided, then the servlet will use the current working directory.
* @return The directory on disk from which to serve files.
*/
protected abstract String getBasePath();
/**
* Returns the file associated with the given HTTP servlet request.
* If this method throws {@link IllegalArgumentException}, then the servlet will return a HTTP 400 error.
* If this method returns null, or if {@link File#isFile()} returns false, then the
* servlet will invoke {@link #handleFileNotFound(HttpServletRequest, HttpServletResponse)}.
* @param request The involved HTTP servlet request.
* @return The file associated with the given HTTP servlet request.
* @throws IllegalArgumentException When the request is mangled in such way that it's not recognizable as a valid
* file request. The servlet will then return a HTTP 400 error.
*/
protected File getFile(HttpServletRequest request) {
String pathInfo = request.getPathInfo();
if (pathInfo == null || pathInfo.isEmpty()) {
throw new IllegalArgumentException(); // Trigger a HTTP 400 "Bad Request" error
}
if (pathInfo.endsWith("/")) {
pathInfo += "index.html";
}
return new File(getBasePath(), pathInfo);
}
/**
* Handles the case when the file is not found.
*
* The default implementation sends a HTTP 404 error.
* @param request The involved HTTP servlet request.
* @param response The involved HTTP servlet response.
* @throws IOException When something fails at I/O level.
* @since 2.3
*/
protected void handleFileNotFound(HttpServletRequest request, HttpServletResponse response) throws IOException {
response.sendError(HttpServletResponse.SC_NOT_FOUND);
}
/**
* Returns how long the resource may be cached by the client before it expires, in seconds.
*
* The default implementation returns 30 days in seconds.
* @param request The involved HTTP servlet request.
* @param file The involved file.
* @return The client cache expire time in seconds (not milliseconds!).
*/
protected long getExpireTime(HttpServletRequest request, File file) {
return DEFAULT_EXPIRE_TIME_IN_SECONDS;
}
/**
* Returns the content type associated with the given HTTP servlet request and file.
*
* The default implementation delegates {@link File#getName()} to {@link ServletContext#getMimeType(String)} with a
* fallback default value of application/octet-stream.
* @param request The involved HTTP servlet request.
* @param file The involved file.
* @return The content type associated with the given HTTP servlet request and file.
*/
protected String getContentType(HttpServletRequest request, File file) {
return coalesce(request.getServletContext().getMimeType(file.getName()), "application/octet-stream");
}
/**
* Returns true if we must force a "Save As" dialog based on the given HTTP servlet request and content
* type as obtained from {@link #getContentType(HttpServletRequest, File)}.
*
* The default implementation will return true if the content type does not start with
* text or image, and the Accept request header is either null
* or does not match the given content type.
* @param request The involved HTTP servlet request.
* @param contentType The content type of the involved file.
* @return true if we must force a "Save As" dialog based on the given HTTP servlet request and content
* type.
*/
protected boolean isAttachment(HttpServletRequest request, String contentType) {
String accept = request.getHeader("Accept");
return !startsWithOneOf(contentType, "text", "image") && (accept == null || !accepts(accept, contentType));
}
/**
* Returns the file name to be used in Content-Disposition header.
* This does not need to be URL-encoded as this will be taken care of.
*
* The default implementation returns {@link File#getName()}.
* @param request The involved HTTP servlet request.
* @param file The involved file.
* @return The file name to be used in Content-Disposition header.
* @since 2.3
*/
protected String getAttachmentName(HttpServletRequest request, File file) {
return file.getName();
}
// Sub-actions ----------------------------------------------------------------------------------------------------
/**
* Returns true if it's a conditional request which must return 412.
*/
private boolean preconditionFailed(HttpServletRequest request, Resource resource) {
String match = request.getHeader("If-Match");
long unmodified = request.getDateHeader("If-Unmodified-Since");
return (match != null) ? !matches(match, resource.eTag) : (unmodified != -1 && modified(unmodified, resource.lastModified));
}
/**
* Set cache headers.
*/
private void setCacheHeaders(HttpServletResponse response, Resource resource, long expires) {
setCacheHeaders(response, expires);
response.setHeader("ETag", resource.eTag);
response.setDateHeader("Last-Modified", resource.lastModified);
}
/**
* Returns true if it's a conditional request which must return 304.
*/
private boolean notModified(HttpServletRequest request, Resource resource) {
String noMatch = request.getHeader("If-None-Match");
long modified = request.getDateHeader("If-Modified-Since");
return (noMatch != null) ? matches(noMatch, resource.eTag) : (modified != -1 && !modified(modified, resource.lastModified));
}
/**
* Get requested ranges. If this is null, then we must return 416. If this is empty, then we must return full file.
*/
private List getRanges(HttpServletRequest request, Resource resource) {
List ranges = new ArrayList<>(1);
String rangeHeader = request.getHeader("Range");
if (rangeHeader == null) {
return ranges;
}
else if (!RANGE_PATTERN.matcher(rangeHeader).matches()) {
return null; // Syntax error.
}
String ifRange = request.getHeader("If-Range");
if (ifRange != null && !ifRange.equals(resource.eTag)) {
try {
long ifRangeTime = request.getDateHeader("If-Range");
if (ifRangeTime != -1 && modified(ifRangeTime, resource.lastModified)) {
return ranges;
}
}
catch (IllegalArgumentException ifRangeHeaderIsInvalid) {
logger.log(FINE, "If-Range header is invalid. Just return full file then.", ifRangeHeaderIsInvalid);
return ranges;
}
}
for (String rangeHeaderPart : rangeHeader.split("=")[1].split(",")) {
Range range = parseRange(rangeHeaderPart, resource.length);
if (range == null) {
return null; // Logic error.
}
ranges.add(range);
}
return ranges;
}
/**
* Parse range header part. Returns null if there's a logic error (i.e. start after end).
*/
private Range parseRange(String range, long length) {
long start = sublong(range, 0, range.indexOf('-'));
long end = sublong(range, range.indexOf('-') + 1, range.length());
if (start == -1) {
start = length - end;
end = length - 1;
}
else if (end == -1 || end > length - 1) {
end = length - 1;
}
if (start > end) {
return null; // Logic error.
}
return new Range(start, end);
}
/**
* Set content headers.
*/
private String setContentHeaders(HttpServletRequest request, HttpServletResponse response, Resource resource, List ranges) {
String contentType = getContentType(request, resource.file);
String filename = getAttachmentName(request, resource.file);
boolean attachment = isAttachment(request, contentType);
response.setHeader("Content-Disposition", formatContentDispositionHeader(filename, attachment));
response.setHeader("Accept-Ranges", "bytes");
if (ranges.size() == 1) {
Range range = ranges.get(0);
response.setContentType(contentType);
response.setHeader("Content-Length", String.valueOf(range.length));
if (response.getStatus() == HttpServletResponse.SC_PARTIAL_CONTENT) {
response.setHeader("Content-Range", "bytes " + range.start + "-" + range.end + "/" + resource.length);
}
}
else {
response.setContentType("multipart/byteranges; boundary=" + MULTIPART_BOUNDARY);
}
return contentType;
}
/**
* Write given file to response with given content type and ranges.
*/
private void writeContent(HttpServletResponse response, Resource resource, List ranges, String contentType) throws IOException {
ServletOutputStream output = response.getOutputStream();
if (ranges.size() == 1) {
Range range = ranges.get(0);
stream(resource.file, output, range.start, range.length);
}
else {
for (Range range : ranges) {
output.println();
output.println("--" + MULTIPART_BOUNDARY);
output.println("Content-Type: " + contentType);
output.println("Content-Range: bytes " + range.start + "-" + range.end + "/" + resource.length);
stream(resource.file, output, range.start, range.length);
}
output.println();
output.println("--" + MULTIPART_BOUNDARY + "--");
}
}
// Helpers --------------------------------------------------------------------------------------------------------
/**
* Returns true if the given match header matches the given ETag value.
*/
private static boolean matches(String matchHeader, String eTag) {
String[] matchValues = matchHeader.split("\\s*,\\s*");
Arrays.sort(matchValues);
return Arrays.binarySearch(matchValues, eTag) > -1
|| Arrays.binarySearch(matchValues, "*") > -1;
}
/**
* Returns true if the given modified header is older than the given last modified value.
*/
private static boolean modified(long modifiedHeader, long lastModified) {
return (modifiedHeader + ONE_SECOND_IN_MILLIS <= lastModified); // That second is because the header is in seconds, not millis.
}
/**
* Returns a substring of the given string value from the given begin index to the given end index as a long.
* If the substring is empty, then -1 will be returned.
*/
private static long sublong(String value, int beginIndex, int endIndex) {
String substring = value.substring(beginIndex, endIndex);
return substring.isEmpty() ? -1 : Long.parseLong(substring);
}
/**
* Returns true if the given accept header accepts the given value.
*/
private static boolean accepts(String acceptHeader, String toAccept) {
String[] acceptValues = acceptHeader.split("\\s*[,;]\\s*");
Arrays.sort(acceptValues);
return Arrays.binarySearch(acceptValues, toAccept) > -1
|| Arrays.binarySearch(acceptValues, toAccept.replaceAll("/.*$", "/*")) > -1
|| Arrays.binarySearch(acceptValues, "*/*") > -1;
}
// Nested classes -------------------------------------------------------------------------------------------------
/**
* Convenience class for a file resource.
*/
private static class Resource {
private final File file;
private final long length;
private final long lastModified;
private final String eTag;
public Resource(File file) {
if (file != null && file.isFile()) {
this.file = file;
length = file.length();
lastModified = file.lastModified();
eTag = format(ETAG, encodeURL(file.getName()), lastModified);
}
else {
this.file = null;
length = 0;
lastModified = 0;
eTag = null;
}
}
}
/**
* Convenience class for a byte range.
*/
private static class Range {
private final long start;
private final long end;
private final long length;
public Range(long start, long end) {
this.start = start;
this.end = end;
length = end - start + 1;
}
}
// Servlet Utils --------------------------------------------------------------------------------------------------------
private static final String CONTENT_DISPOSITION_HEADER = "%s;filename=\"%2$s\"; filename*=UTF-8''%2$s";
/**
* Format an UTF-8 compatible content disposition header for the given filename and whether it's an attachment.
* @param filename The filename to appear in "Save As" dialogue.
* @param attachment Whether the content should be provided as an attachment or inline.
* @return An UTF-8 compatible content disposition header.
* @since 2.6
*/
public static String formatContentDispositionHeader(String filename, boolean attachment) {
return format(CONTENT_DISPOSITION_HEADER, (attachment ? "attachment" : "inline"), encodeURI(filename));
}
/**
*
Set the cache headers. If the expires argument is larger than 0 seconds, then the following headers
* will be set:
*
* Cache-Control: public,max-age=[expiration time in seconds],must-revalidateExpires: [expiration date of now plus expiration time in seconds]
* Else the method will delegate to {@link #setNoCacheHeaders(HttpServletResponse)}.
* @param response The HTTP servlet response to set the headers on.
* @param expires The expire time in seconds (not milliseconds!).
* @since 2.2
*/
public static void setCacheHeaders(HttpServletResponse response, long expires) {
if (expires > 0) {
response.setHeader("Cache-Control", "public,max-age=" + expires + ",must-revalidate");
response.setDateHeader("Expires", System.currentTimeMillis() + SECONDS.toMillis(expires));
response.setHeader("Pragma", ""); // Explicitly set pragma to prevent container from overriding it.
}
else {
setNoCacheHeaders(response);
}
}
/**
*
Set the no-cache headers. The following headers will be set:
*
* Cache-Control: no-cache,no-store,must-revalidateExpires: [expiration date of 0]Pragma: no-cache
* Set the no-cache headers.
* @param response The HTTP servlet response to set the headers on.
* @since 2.2
*/
public static void setNoCacheHeaders(HttpServletResponse response) {
response.setHeader("Cache-Control", "no-cache,no-store,must-revalidate");
response.setDateHeader("Expires", 0);
response.setHeader("Pragma", "no-cache"); // Backwards compatibility for HTTP 1.0.
}
// Basic Utils --------------------------------------------------------------------------------------------------------
/**
* Returns the first non-null object of the argument list, or null if there is no such
* element.
* @param The generic object type.
* @param objects The argument list of objects to be tested for non-null.
* @return The first non-null object of the argument list, or null if there is no such
* element.
*/
@SafeVarargs
public static T coalesce(T... objects) {
for (T object : objects) {
if (object != null) {
return object;
}
}
return null;
}
private static final String ERROR_UNSUPPORTED_ENCODING = "UTF-8 is apparently not supported on this platform.";
/**
* URL-encode the given string using UTF-8.
* @param string The string to be URL-encoded using UTF-8.
* @return The given string, URL-encoded using UTF-8, or null if null was given.
* @throws UnsupportedOperationException When this platform does not support UTF-8.
* @since 1.4
*/
public static String encodeURL(String string) {
if (string == null) {
return null;
}
try {
return URLEncoder.encode(string, UTF_8.name());
}
catch (UnsupportedEncodingException e) {
throw new UnsupportedOperationException(ERROR_UNSUPPORTED_ENCODING, e);
}
}
/**
* Returns true if the given string starts with one of the given prefixes.
* @param string The object to be checked if it starts with one of the given prefixes.
* @param prefixes The argument list of prefixes to be checked
* @return true if the given string starts with one of the given prefixes.
* @since 1.4
*/
public static boolean startsWithOneOf(String string, String... prefixes) {
for (String prefix : prefixes) {
if (string.startsWith(prefix)) {
return true;
}
}
return false;
}
/**
* URI-encode the given string using UTF-8. URIs (paths and filenames) have different encoding rules as compared to
* URL query string parameters. {@link URLEncoder} is actually only for www (HTML) form based query string parameter
* values (as used when a webbrowser submits a HTML form). URI encoding has a lot in common with URL encoding, but
* the space has to be %20 and some chars doesn't necessarily need to be encoded.
* @param string The string to be URI-encoded using UTF-8.
* @return The given string, URI-encoded using UTF-8, or null if null was given.
* @throws UnsupportedOperationException When this platform does not support UTF-8.
* @since 2.4
*/
public static String encodeURI(String string) {
if (string == null) {
return null;
}
return encodeURL(string)
.replace("+", "%20")
.replace("%21", "!")
.replace("%27", "'")
.replace("%28", "(")
.replace("%29", ")")
.replace("%7E", "~");
}
private static final int DEFAULT_STREAM_BUFFER_SIZE = 10240;
/**
* Stream the given input to the given output via NIO {@link Channels} and a directly allocated NIO
* {@link ByteBuffer}. Both the input and output streams will implicitly be closed after streaming,
* regardless of whether an exception is been thrown or not.
* @param input The input stream.
* @param output The output stream.
* @throws IOException When an I/O error occurs.
*/
public static void stream(InputStream input, OutputStream output) throws IOException {
try (ReadableByteChannel inputChannel = Channels.newChannel(input);
WritableByteChannel outputChannel = Channels.newChannel(output))
{
ByteBuffer buffer = ByteBuffer.allocateDirect(DEFAULT_STREAM_BUFFER_SIZE);
long size = 0;
while (inputChannel.read(buffer) != -1) {
((Buffer) buffer).flip();
size += outputChannel.write(buffer);
((Buffer) buffer).clear();
}
}
}
/**
* Stream a specified range of the given file to the given output via NIO {@link Channels} and a directly allocated
* NIO {@link ByteBuffer}. The output stream will only implicitly be closed after streaming when the specified range
* represents the whole file, regardless of whether an exception is been thrown or not.
* @param file The file.
* @param output The output stream.
* @param start The start position (offset).
* @param length The (intented) length of written bytes.
* @throws IOException When an I/O error occurs.
* @since 2.2
*/
public static void stream(File file, OutputStream output, long start, long length) throws IOException {
if (start == 0 && length >= file.length()) {
stream(new FileInputStream(file), output);
return;
}
try (FileChannel fileChannel = (FileChannel) Files.newByteChannel(file.toPath(), StandardOpenOption.READ);
WritableByteChannel outputChannel = Channels.newChannel(output)) {
ByteBuffer buffer = ByteBuffer.allocateDirect(DEFAULT_STREAM_BUFFER_SIZE);
long size = 0;
while (fileChannel.read(buffer, start + size) != -1) {
((Buffer) buffer).flip();
if (size + buffer.limit() > length) {
((Buffer) buffer).limit((int) (length - size));
}
size += outputChannel.write(buffer);
if (size >= length) {
break;
}
((Buffer) buffer).clear();
}
}
}
}