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/**
* Copyright 2013 Florian Schmaus
*
* All rights reserved. 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.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
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 is available since Java7, so it will only work with Java7 or higher (hence it's name).
*
* @author Florian Schmaus
* @see <a
* href="http://docs.oracle.com/javase/7/docs/api/java/util/zip/Deflater.html#deflate(byte[], int, int, int)">The
* required deflate() method</a>
*
*/
public class Java7ZlibInputOutputStream extends XMPPInputOutputStream {
private final static Method method;
private final static boolean supported;
private final static int compressionLevel = Deflater.DEFAULT_STRATEGY;
static {
Method m = null;
try {
m = Deflater.class.getMethod("deflate", byte[].class, int.class, int.class, int.class);
} catch (SecurityException e) {
} catch (NoSuchMethodException e) {
}
method = m;
supported = (method != null);
}
public Java7ZlibInputOutputStream() {
compressionMethod = "zlib";
}
@Override
public boolean isSupported() {
return supported;
}
@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
*/
@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) {
return new DeflaterOutputStream(outputStream, new Deflater(compressionLevel)) {
public void flush() throws IOException {
if (!supported) {
super.flush();
return;
}
int count = 0;
if (!def.needsInput()) {
do {
count = def.deflate(buf, 0, buf.length);
out.write(buf, 0, count);
} while (count > 0);
out.flush();
}
try {
do {
count = (Integer) method.invoke(def, buf, 0, buf.length, 2);
out.write(buf, 0, count);
} while (count > 0);
} catch (IllegalArgumentException e) {
throw new IOException("Can't flush");
} catch (IllegalAccessException e) {
throw new IOException("Can't flush");
} catch (InvocationTargetException e) {
throw new IOException("Can't flush");
}
super.flush();
}
};
}
}
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