I would like to create a version of Java’s deflater not synchronizing on its ZStreamRef instance.
I started by copying the code into a Deflater2 class. The code compiles, however, when I create an instance of that class, I get:
Exception in thread "main" java.lang.UnsatisfiedLinkError: net.dwst.bricolo.ResetGZip.Deflater2.initIDs()V
at net.mypackage.Deflater2.initIDs(Native Method)
at net.mypackage.Deflater2.<clinit>(Deflater2.java:65)
at net.mypackage.SpeedTest.main(SpeedTest.java:13)
How can I create an instance of Deflater2 without triggering this exception?
I am providing the code for Deflater2:
package net.mypackage;
public class Deflater2 {
private final ZStreamRef zsRef;
private byte[] buf = new byte[0];
private int off, len;
private int level, strategy;
private boolean setParams;
private boolean finish, finished;
/**
* Compression method for the deflate algorithm (the only one currently
* supported).
*/
public static final int DEFLATED = 8;
/**
* Compression level for no compression.
*/
public static final int NO_COMPRESSION = 0;
/**
* Compression level for fastest compression.
*/
public static final int BEST_SPEED = 1;
/**
* Compression level for best compression.
*/
public static final int BEST_COMPRESSION = 9;
/**
* Default compression level.
*/
public static final int DEFAULT_COMPRESSION = -1;
/**
* Compression strategy best used for data consisting mostly of small
* values with a somewhat random distribution. Forces more Huffman coding
* and less string matching.
*/
public static final int FILTERED = 1;
/**
* Compression strategy for Huffman coding only.
*/
public static final int HUFFMAN_ONLY = 2;
/**
* Default compression strategy.
*/
public static final int DEFAULT_STRATEGY = 0;
static {
/* Zip library is loaded from System.initializeSystemClass */
initIDs();
}
/**
* Creates a new compressor using the specified compression level.
* If 'nowrap' is true then the ZLIB header and checksum fields will
* not be used in order to support the compression format used in
* both GZIP and PKZIP.
* @param level the compression level (0-9)
* @param nowrap if true then use GZIP compatible compression
*/
public Deflater2(int level, boolean nowrap) {
this.level = level;
this.strategy = DEFAULT_STRATEGY;
this.zsRef = new ZStreamRef(init(level, DEFAULT_STRATEGY, nowrap));
}
/**
* Creates a new compressor using the specified compression level.
* Compressed data will be generated in ZLIB format.
* @param level the compression level (0-9)
*/
public Deflater2(int level) {
this(level, false);
}
/**
* Creates a new compressor with the default compression level.
* Compressed data will be generated in ZLIB format.
*/
public Deflater2() {
this(DEFAULT_COMPRESSION, false);
}
/**
* Sets input data for compression. This should be called whenever
* needsInput() returns true indicating that more input data is required.
* @param b the input data bytes
* @param off the start offset of the data
* @param len the length of the data
* @see Deflater#needsInput
*/
public void setInput(byte[] b, int off, int len) {
if (b== null) {
throw new NullPointerException();
}
if (off < 0 || len < 0 || off > b.length - len) {
throw new ArrayIndexOutOfBoundsException();
}
synchronized (zsRef) {
this.buf = b;
this.off = off;
this.len = len;
}
}
/**
* Sets input data for compression. This should be called whenever
* needsInput() returns true indicating that more input data is required.
* @param b the input data bytes
* @see Deflater#needsInput
*/
public void setInput(byte[] b) {
setInput(b, 0, b.length);
}
/**
* Sets preset dictionary for compression. A preset dictionary is used
* when the history buffer can be predetermined. When the data is later
* uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
* in order to get the Adler-32 value of the dictionary required for
* decompression.
* @param b the dictionary data bytes
* @param off the start offset of the data
* @param len the length of the data
* @see Inflater#inflate
* @see Inflater#getAdler
*/
public void setDictionary(byte[] b, int off, int len) {
if (b == null) {
throw new NullPointerException();
}
if (off < 0 || len < 0 || off > b.length - len) {
throw new ArrayIndexOutOfBoundsException();
}
synchronized (zsRef) {
ensureOpen();
setDictionary(zsRef.address(), b, off, len);
}
}
/**
* Sets preset dictionary for compression. A preset dictionary is used
* when the history buffer can be predetermined. When the data is later
* uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
* in order to get the Adler-32 value of the dictionary required for
* decompression.
* @param b the dictionary data bytes
* @see Inflater#inflate
* @see Inflater#getAdler
*/
public void setDictionary(byte[] b) {
setDictionary(b, 0, b.length);
}
/**
* Sets the compression strategy to the specified value.
* @param strategy the new compression strategy
* @exception IllegalArgumentException if the compression strategy is
* invalid
*/
public void setStrategy(int strategy) {
switch (strategy) {
case DEFAULT_STRATEGY:
case FILTERED:
case HUFFMAN_ONLY:
break;
default:
throw new IllegalArgumentException();
}
synchronized (zsRef) {
if (this.strategy != strategy) {
this.strategy = strategy;
setParams = true;
}
}
}
/**
* Sets the current compression level to the specified value.
* @param level the new compression level (0-9)
* @exception IllegalArgumentException if the compression level is invalid
*/
public void setLevel(int level) {
if ((level < 0 || level > 9) && level != DEFAULT_COMPRESSION) {
throw new IllegalArgumentException("invalid compression level");
}
synchronized (zsRef) {
if (this.level != level) {
this.level = level;
setParams = true;
}
}
}
/**
* Returns true if the input data buffer is empty and setInput()
* should be called in order to provide more input.
* @return true if the input data buffer is empty and setInput()
* should be called in order to provide more input
*/
public boolean needsInput() {
return len <= 0;
}
/**
* When called, indicates that compression should end with the current
* contents of the input buffer.
*/
public void finish() {
synchronized (zsRef) {
finish = true;
}
}
/**
* Returns true if the end of the compressed data output stream has
* been reached.
* @return true if the end of the compressed data output stream has
* been reached
*/
public boolean finished() {
synchronized (zsRef) {
return finished;
}
}
/**
* Fills specified buffer with compressed data. Returns actual number
* of bytes of compressed data. A return value of 0 indicates that
* needsInput() should be called in order to determine if more input
* data is required.
* @param b the buffer for the compressed data
* @param off the start offset of the data
* @param len the maximum number of bytes of compressed data
* @return the actual number of bytes of compressed data
*/
public int deflate(byte[] b, int off, int len) {
if (b == null) {
throw new NullPointerException();
}
if (off < 0 || len < 0 || off > b.length - len) {
throw new ArrayIndexOutOfBoundsException();
}
synchronized (zsRef) {
ensureOpen();
return deflateBytes(zsRef.address(), b, off, len);
}
}
/**
* Fills specified buffer with compressed data. Returns actual number
* of bytes of compressed data. A return value of 0 indicates that
* needsInput() should be called in order to determine if more input
* data is required.
* @param b the buffer for the compressed data
* @return the actual number of bytes of compressed data
*/
public int deflate(byte[] b) {
return deflate(b, 0, b.length);
}
/**
* Returns the ADLER-32 value of the uncompressed data.
* @return the ADLER-32 value of the uncompressed data
*/
public int getAdler() {
synchronized (zsRef) {
ensureOpen();
return getAdler(zsRef.address());
}
}
/**
* Returns the total number of uncompressed bytes input so far.
*
* <p>Since the number of bytes may be greater than
* Integer.MAX_VALUE, the {@link #getBytesRead()} method is now
* the preferred means of obtaining this information.</p>
*
* @return the total number of uncompressed bytes input so far
*/
public int getTotalIn() {
return (int) getBytesRead();
}
/**
* Returns the total number of uncompressed bytes input so far.</p>
*
* @return the total (non-negative) number of uncompressed bytes input so far
* @since 1.5
*/
public long getBytesRead() {
synchronized (zsRef) {
ensureOpen();
return getBytesRead(zsRef.address());
}
}
/**
* Returns the total number of compressed bytes output so far.
*
* <p>Since the number of bytes may be greater than
* Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now
* the preferred means of obtaining this information.</p>
*
* @return the total number of compressed bytes output so far
*/
public int getTotalOut() {
return (int) getBytesWritten();
}
/**
* Returns the total number of compressed bytes output so far.</p>
*
* @return the total (non-negative) number of compressed bytes output so far
* @since 1.5
*/
public long getBytesWritten() {
synchronized (zsRef) {
ensureOpen();
return getBytesWritten(zsRef.address());
}
}
/**
* Resets deflater so that a new set of input data can be processed.
* Keeps current compression level and strategy settings.
*/
public void reset() {
synchronized (zsRef) {
ensureOpen();
reset(zsRef.address());
finish = false;
finished = false;
off = len = 0;
}
}
/**
* Closes the compressor and discards any unprocessed input.
* This method should be called when the compressor is no longer
* being used, but will also be called automatically by the
* finalize() method. Once this method is called, the behavior
* of the Deflater object is undefined.
*/
public void end() {
synchronized (zsRef) {
long addr = zsRef.address();
zsRef.clear();
if (addr != 0) {
end(addr);
buf = null;
}
}
}
/**
* Closes the compressor when garbage is collected.
*/
protected void finalize() {
end();
}
private void ensureOpen() {
assert Thread.holdsLock(zsRef);
if (zsRef.address() == 0)
throw new NullPointerException("Deflater has been closed");
}
private static native void initIDs();
private native static long init(int level, int strategy, boolean nowrap);
private native static void setDictionary(long addr, byte[] b, int off,
int len);
private native int deflateBytes(long addr, byte[] b, int off, int len);
private native static int getAdler(long addr);
private native static long getBytesRead(long addr);
private native static long getBytesWritten(long addr);
private native static void reset(long addr);
private native static void end(long addr);
}
Your problem is not in java code.
There can be the following reasons:
the library that you are using or other library that your library depends on is not in library path (java.library.path option)
One of the native libraries you try to use does not match your platforms. For example you are running on 32 bit platform and trying to use 64bit library.
Take a look here: How to add native library to "java.library.path" with Eclipse launch (instead of overriding it)