/**
*
* Copyright 2013-2020 Florian Schmaus
*
* 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.jivesoftware.smack.compression;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;
/**
* This class provides XMPP "zlib" compression with the help of the Deflater class of the Java API.
* Note that the method needed for compression with synchronous flush support is available since
* Java7, so it will only work with Java7 or higher (hence it's name). On Android, the required
* deflate()
method is available on API 19 or higher.
*
* See also: *
* * @author Florian Schmaus */ public class Java7ZlibInputOutputStream extends XMPPInputOutputStream { private static final int compressionLevel = Deflater.DEFAULT_COMPRESSION; public Java7ZlibInputOutputStream() { super("zlib"); } @Override public boolean isSupported() { return true; } @Override public InputStream getInputStream(InputStream inputStream) { return new InflaterInputStream(inputStream, new Inflater(), 512) { /** * Provide a more InputStream compatible version. A return value of 1 means that it is likely to read one * byte without blocking, 0 means that the system is known to block for more input. * * @return 0 if no data is available, 1 otherwise * @throws IOException if an I/O error occurred. */ @Override public int available() throws IOException { /* * aSmack related remark (where KXmlParser is used): * This is one of the funny code blocks. InflaterInputStream.available violates the contract of * InputStream.available, which breaks kXML2. * * I'm not sure who's to blame, oracle/sun for a broken api or the google guys for mixing a sun bug with * a xml reader that can't handle it.... * * Anyway, this simple if breaks suns distorted reality, but helps to use the api as intended. */ if (inf.needsInput()) { return 0; } return super.available(); } }; } @Override public OutputStream getOutputStream(OutputStream outputStream) { final int flushMethodInt; switch (flushMethod) { case SYNC_FLUSH: flushMethodInt = Deflater.SYNC_FLUSH; break; case FULL_FLUSH: flushMethodInt = Deflater.FULL_FLUSH; break; default: throw new AssertionError(); } return new DeflaterOutputStream(outputStream, new Deflater(compressionLevel)) { @Override public void flush() throws IOException { int count; while ((count = def.deflate(buf, 0, buf.length, flushMethodInt)) > 0) { out.write(buf, 0, count); } super.flush(); } }; } }