static {
List<String> temp = new ArrayList<>(6);
temp.add(GZIP_ENCODING);
temp.add(DEFLATE_ENCODING);
temp.add(COMPRESS_ENCODING);
temp.add(X_GZIP_ENCODING);
temp.add(X_COMPRESS_ENCODING);
temp.add(NO_ENCODING);
SUPPORTED_ENCODINGS = Collections.unmodifiableList(temp);
}
public java.util.List<AirspaceEntry> getEntries() {
return Collections.unmodifiableList(this.entryList);
}
/**
* Implementations of this abstract class can add compression of a particular type to a given {@link
* OutputStream}. They each return a {@link CompressingOutputStream}, which is just a thin wrapper
* on top of an {@link OutputStream} that adds the ability to "finish" a stream (see {@link
* CompressingOutputStream}).
*
* <p>
*
* <p>This class contains implementations based on several popular compression algorithms, such as
* gzip. For example, the gzip implementation can decorate an {@link OutputStream} using an instance
* of {@link GZIPOutputStream} and in that way add gzip compression to the stream.
*
* @author Sean Owen
*/
abstract class CompressingStreamFactory {
/** "No encoding" content type: "identity". */
static final String NO_ENCODING = "identity";
private static final Logger LOG = LoggerFactory.getLogger(CompressingStreamFactory.class);
/** Implementation based on {@link GZIPOutputStream} and {@link GZIPInputStream}. */
private static final CompressingStreamFactory GZIP_CSF = new GZIPCompressingStreamFactory();
/** Implementation based on {@link ZipOutputStream} and {@link ZipInputStream}. */
private static final CompressingStreamFactory ZIP_CSF = new ZipCompressingStreamFactory();
/** Implementation based on {@link DeflaterOutputStream}. */
private static final CompressingStreamFactory DEFLATE_CSF = new DeflateCompressingStreamFactory();
private static final String GZIP_ENCODING = "gzip";
private static final String X_GZIP_ENCODING = "x-gzip";
private static final String DEFLATE_ENCODING = "deflate";
private static final String COMPRESS_ENCODING = "compress";
private static final String X_COMPRESS_ENCODING = "x-compress";
static final List<String> ALL_COMPRESSION_ENCODINGS =
Collections.unmodifiableList(
Arrays.asList(
GZIP_ENCODING,
DEFLATE_ENCODING,
COMPRESS_ENCODING,
X_GZIP_ENCODING,
X_COMPRESS_ENCODING));
/** "Any encoding" content type: the "*" wildcard. */
private static final String ANY_ENCODING = "*";
/** Ordered list of preferred encodings, from most to least preferred */
private static final List<String> SUPPORTED_ENCODINGS;
/**
* Cache mapping previously seen "Accept-Encoding" header Strings to an appropriate instance of
* {@link CompressingStreamFactory}.
*/
private static final Map<String, String> BEST_ENCODING_CACHE =
Collections.synchronizedMap(new HashMap<String, String>(101));
/** Maps content type String to appropriate implementation of {@link CompressingStreamFactory}. */
private static final Map<String, CompressingStreamFactory> FACTORY_MAP;
private static final Pattern COMMA = Pattern.compile(",");
static {
List<String> temp = new ArrayList<>(6);
temp.add(GZIP_ENCODING);
temp.add(DEFLATE_ENCODING);
temp.add(COMPRESS_ENCODING);
temp.add(X_GZIP_ENCODING);
temp.add(X_COMPRESS_ENCODING);
temp.add(NO_ENCODING);
SUPPORTED_ENCODINGS = Collections.unmodifiableList(temp);
}
static {
Map<String, CompressingStreamFactory> temp = new HashMap<>(11);
temp.put(GZIP_ENCODING, GZIP_CSF);
temp.put(X_GZIP_ENCODING, GZIP_CSF);
temp.put(COMPRESS_ENCODING, ZIP_CSF);
temp.put(X_COMPRESS_ENCODING, ZIP_CSF);
temp.put(DEFLATE_ENCODING, DEFLATE_CSF);
FACTORY_MAP = Collections.unmodifiableMap(temp);
}
private static OutputStream maybeWrapStatsOutputStream(
OutputStream outputStream,
CompressingFilterContext context,
CompressingFilterStats.StatsField field) {
assert outputStream != null;
OutputStream result;
if (context.isStatsEnabled()) {
CompressingFilterStats stats = context.getStats();
CompressingFilterStats.OutputStatsCallback callbackOutput =
stats.getOutputStatsCallback(field);
result = new StatsOutputStream(outputStream, callbackOutput);
} else {
result = outputStream;
}
return result;
}
private static InputStream maybeWrapStatsInputStream(
InputStream inputStream,
CompressingFilterContext context,
CompressingFilterStats.StatsField field) {
assert inputStream != null;
InputStream result;
if (context.isStatsEnabled()) {
CompressingFilterStats stats = context.getStats();
CompressingFilterStats.InputStatsCallback callbackInput = stats.getInputStatsCallback(field);
result = new StatsInputStream(inputStream, callbackInput);
} else {
result = inputStream;
}
return result;
}
private static boolean isSupportedResponseContentEncoding(String contentEncoding) {
return NO_ENCODING.equals(contentEncoding) || FACTORY_MAP.containsKey(contentEncoding);
}
static boolean isSupportedRequestContentEncoding(String contentEncoding) {
return NO_ENCODING.equals(contentEncoding) || FACTORY_MAP.containsKey(contentEncoding);
}
/**
* Returns the instance associated to the given content encoding.
*
* @param contentEncoding content encoding (e.g. "gzip")
* @return instance for content encoding
*/
static CompressingStreamFactory getFactoryForContentEncoding(String contentEncoding) {
assert FACTORY_MAP.containsKey(contentEncoding);
return FACTORY_MAP.get(contentEncoding);
}
/**
* Determines best content encoding for the response, based on the request -- in particular, based
* on its "Accept-Encoding" header.
*
* @param httpRequest request
* @return best content encoding
*/
static String getBestContentEncoding(HttpServletRequest httpRequest) {
String forcedEncoding = (String) httpRequest.getAttribute(CompressingFilter.FORCE_ENCODING_KEY);
String bestEncoding;
if (forcedEncoding != null) {
bestEncoding = forcedEncoding;
} else {
String acceptEncodingHeader =
httpRequest.getHeader(CompressingHttpServletResponse.ACCEPT_ENCODING_HEADER);
if (acceptEncodingHeader == null) {
bestEncoding = NO_ENCODING;
} else {
bestEncoding = BEST_ENCODING_CACHE.get(acceptEncodingHeader);
if (bestEncoding == null) {
// No cached value; must parse header to determine best encoding
// I don't synchronize on bestEncodingCache; it's not worth it to avoid the rare case
// where
// two thread get in here and both parse the header. It's only a tiny bit of extra work,
// and
// avoids the synchronization overhead.
if (acceptEncodingHeader.indexOf((int) ',') >= 0) {
// multiple encodings are accepted
bestEncoding = selectBestEncoding(acceptEncodingHeader);
} else {
// one encoding is accepted
bestEncoding = parseBestEncoding(acceptEncodingHeader);
}
BEST_ENCODING_CACHE.put(acceptEncodingHeader, bestEncoding);
}
}
}
// User-specified encoding might not be supported
if (!isSupportedResponseContentEncoding(bestEncoding)) {
bestEncoding = NO_ENCODING;
}
return bestEncoding;
}
private static String parseBestEncoding(String acceptEncodingHeader) {
ContentEncodingQ contentEncodingQ = parseContentEncodingQ(acceptEncodingHeader);
String contentEncoding = contentEncodingQ.getContentEncoding();
if (contentEncodingQ.getQ() > 0.0) {
if (ANY_ENCODING.equals(contentEncoding)) {
return SUPPORTED_ENCODINGS.get(0);
} else if (SUPPORTED_ENCODINGS.contains(contentEncoding)) {
return contentEncoding;
}
}
return NO_ENCODING;
}
@SuppressWarnings("squid:S1244")
private static String selectBestEncoding(String acceptEncodingHeader) {
// multiple encodings are accepted; determine best one
Collection<String> bestEncodings = new HashSet<>(3);
double bestQ = 0.0;
Collection<String> unacceptableEncodings = new HashSet<>(3);
boolean willAcceptAnything = false;
for (String token : COMMA.split(acceptEncodingHeader)) {
ContentEncodingQ contentEncodingQ = parseContentEncodingQ(token);
String contentEncoding = contentEncodingQ.getContentEncoding();
double q = contentEncodingQ.getQ();
if (ANY_ENCODING.equals(contentEncoding)) {
willAcceptAnything = q > 0.0;
} else if (SUPPORTED_ENCODINGS.contains(contentEncoding)) {
if (q > 0.0) {
// This is a header quality comparison.
// So it is safe to suppress warning squid:S1244
if (q == bestQ) {
bestEncodings.add(contentEncoding);
} else if (q > bestQ) {
bestQ = q;
bestEncodings.clear();
bestEncodings.add(contentEncoding);
}
} else {
unacceptableEncodings.add(contentEncoding);
}
}
}
if (bestEncodings.isEmpty()) {
// nothing was acceptable to us
if (willAcceptAnything) {
if (unacceptableEncodings.isEmpty()) {
return SUPPORTED_ENCODINGS.get(0);
} else {
for (String encoding : SUPPORTED_ENCODINGS) {
if (!unacceptableEncodings.contains(encoding)) {
return encoding;
}
}
}
}
} else {
for (String encoding : SUPPORTED_ENCODINGS) {
if (bestEncodings.contains(encoding)) {
return encoding;
}
}
}
return NO_ENCODING;
}
private static ContentEncodingQ parseContentEncodingQ(String contentEncodingString) {
double q = 1.0;
int qvalueStartIndex = contentEncodingString.indexOf((int) ';');
String contentEncoding;
if (qvalueStartIndex >= 0) {
contentEncoding = contentEncodingString.substring(0, qvalueStartIndex).trim();
String qvalueString = contentEncodingString.substring(qvalueStartIndex + 1).trim();
if (qvalueString.startsWith("q=")) {
try {
q = Double.parseDouble(qvalueString.substring(2));
} catch (NumberFormatException ignored) {
// That's bad -- browser sent an invalid number. All we can do is ignore it, and
// pretend that no q value was specified, so that it effectively defaults to 1.0
LOG.trace("Couldn't parse a Double from {}.", qvalueString.substring(2), ignored);
}
}
} else {
contentEncoding = contentEncodingString.trim();
}
return new ContentEncodingQ(contentEncoding, q);
}
abstract CompressingOutputStream getCompressingStream(
OutputStream servletOutputStream, CompressingFilterContext context) throws IOException;
abstract CompressingInputStream getCompressingStream(
InputStream servletInputStream, CompressingFilterContext context) throws IOException;
private static final class ContentEncodingQ {
private final String contentEncoding;
private final double q;
private ContentEncodingQ(String contentEncoding, double q) {
assert contentEncoding != null && contentEncoding.length() > 0;
this.contentEncoding = contentEncoding;
this.q = q;
}
String getContentEncoding() {
return contentEncoding;
}
double getQ() {
return q;
}
@Override
public String toString() {
return contentEncoding + ";q=" + q;
}
}
private static class GZIPCompressingStreamFactory extends CompressingStreamFactory {
@Override
CompressingOutputStream getCompressingStream(
final OutputStream outputStream, final CompressingFilterContext context)
throws IOException {
return new CompressingOutputStream() {
private final DeflaterOutputStream gzipOutputStream =
new GZIPOutputStream(
CompressingStreamFactory.maybeWrapStatsOutputStream(
outputStream,
context,
CompressingFilterStats.StatsField.RESPONSE_COMPRESSED_BYTES));
private final OutputStream statsOutputStream =
CompressingStreamFactory.maybeWrapStatsOutputStream(
gzipOutputStream, context, CompressingFilterStats.StatsField.RESPONSE_INPUT_BYTES);
@Override
public OutputStream getCompressingOutputStream() {
return statsOutputStream;
}
@Override
public void finish() throws IOException {
gzipOutputStream.finish();
}
};
}
@Override
CompressingInputStream getCompressingStream(
final InputStream inputStream, final CompressingFilterContext context) {
return new CompressingInputStream() {
@Override
public InputStream getCompressingInputStream() throws IOException {
return CompressingStreamFactory.maybeWrapStatsInputStream(
new GZIPInputStream(
CompressingStreamFactory.maybeWrapStatsInputStream(
inputStream,
context,
CompressingFilterStats.StatsField.REQUEST_COMPRESSED_BYTES)),
context,
CompressingFilterStats.StatsField.REQUEST_INPUT_BYTES);
}
};
}
}
private static class ZipCompressingStreamFactory extends CompressingStreamFactory {
@Override
CompressingOutputStream getCompressingStream(
final OutputStream outputStream, final CompressingFilterContext context) {
return new CompressingOutputStream() {
private final DeflaterOutputStream zipOutputStream =
new ZipOutputStream(
CompressingStreamFactory.maybeWrapStatsOutputStream(
outputStream,
context,
CompressingFilterStats.StatsField.RESPONSE_COMPRESSED_BYTES));
private final OutputStream statsOutputStream =
CompressingStreamFactory.maybeWrapStatsOutputStream(
zipOutputStream, context, CompressingFilterStats.StatsField.RESPONSE_INPUT_BYTES);
@Override
public OutputStream getCompressingOutputStream() {
return statsOutputStream;
}
@Override
public void finish() throws IOException {
zipOutputStream.finish();
}
};
}
@Override
CompressingInputStream getCompressingStream(
final InputStream inputStream, final CompressingFilterContext context) {
return new CompressingInputStream() {
@Override
public InputStream getCompressingInputStream() {
return CompressingStreamFactory.maybeWrapStatsInputStream(
new ZipInputStream(
CompressingStreamFactory.maybeWrapStatsInputStream(
inputStream,
context,
CompressingFilterStats.StatsField.REQUEST_COMPRESSED_BYTES)),
context,
CompressingFilterStats.StatsField.REQUEST_INPUT_BYTES);
}
};
}
}
private static class DeflateCompressingStreamFactory extends CompressingStreamFactory {
@Override
CompressingOutputStream getCompressingStream(
final OutputStream outputStream, final CompressingFilterContext context) {
return new CompressingOutputStream() {
private final DeflaterOutputStream deflaterOutputStream =
new DeflaterOutputStream(
CompressingStreamFactory.maybeWrapStatsOutputStream(
outputStream,
context,
CompressingFilterStats.StatsField.RESPONSE_COMPRESSED_BYTES));
private final OutputStream statsOutputStream =
CompressingStreamFactory.maybeWrapStatsOutputStream(
deflaterOutputStream,
context,
CompressingFilterStats.StatsField.RESPONSE_INPUT_BYTES);
@Override
public OutputStream getCompressingOutputStream() {
return statsOutputStream;
}
@Override
public void finish() throws IOException {
deflaterOutputStream.finish();
}
};
}
@Override
CompressingInputStream getCompressingStream(
final InputStream inputStream, final CompressingFilterContext context) {
return new CompressingInputStream() {
@Override
public InputStream getCompressingInputStream() {
return CompressingStreamFactory.maybeWrapStatsInputStream(
new InflaterInputStream(
CompressingStreamFactory.maybeWrapStatsInputStream(
inputStream,
context,
CompressingFilterStats.StatsField.REQUEST_COMPRESSED_BYTES)),
context,
CompressingFilterStats.StatsField.REQUEST_INPUT_BYTES);
}
};
}
}
}
