Java StreamingXXHash32类代码示例

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
public static int hashOfFile(
        final Path file,
        final int salt) throws IOException {

    Preconditions.checkNotNull(file, "file is null");

    StreamingXXHash32 hash32 = FACTORY.newStreamingHash32(salt);
    ByteBuffer buf = ByteBuffer.allocate(8192);
    byte[] b = new byte[8192];

    try (FileInputStream in = new FileInputStream(file.toFile())) {
        FileChannel channel = in.getChannel();
        long len;
        while ((len = channel.read(buf)) != -1) {
            buf.flip();
            buf.get(b, 0, (int) len);
            hash32.update(b, 0, (int) len);
            buf.clear();
        }
    }
    return hash32.getValue();
}
 

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
private Integer fastHashing(String strData) throws IOException{
	byte[] data = strData.getBytes();
	
	ByteArrayInputStream in = new ByteArrayInputStream(data);

	int seed = 0x9747b28c; // used to initialize the hash value, use whatever
	                       // value you want, but always the same
	
	StreamingXXHash32 hash32 = factory.newStreamingHash32(seed);
	byte[] buf = new byte[8]; // for real-world usage, use a larger buffer, like 8192 bytes
	for (;;) {
	  int read = in.read(buf);
	  if (read == -1) {
	    break;
	  }
	  hash32.update(buf, 0, read);
	}
	Integer hash = hash32.getValue();
	
	return hash;
}
 

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
private static ByteBuf compressBlock(LZ4Compressor compressor, StreamingXXHash32 checksum, byte[] bytes, int off, int len) {
	assert len != 0;

	int compressionLevel = compressionLevel(len < MIN_BLOCK_SIZE ? MIN_BLOCK_SIZE : len);

	int outputBufMaxSize = HEADER_LENGTH + ((compressor == null) ? len : compressor.maxCompressedLength(len));
	ByteBuf outputBuf = ByteBufPool.allocate(outputBufMaxSize);
	outputBuf.put(MAGIC);

	byte[] outputBytes = outputBuf.array();

	checksum.reset();
	checksum.update(bytes, off, len);
	int check = checksum.getValue();

	int compressedLength = len;
	if (compressor != null) {
		compressedLength = compressor.compress(bytes, off, len, outputBytes, HEADER_LENGTH);
	}

	int compressMethod;
	if (compressor == null || compressedLength >= len) {
		compressMethod = COMPRESSION_METHOD_RAW;
		compressedLength = len;
		System.arraycopy(bytes, off, outputBytes, HEADER_LENGTH, len);
	} else {
		compressMethod = COMPRESSION_METHOD_LZ4;
	}

	outputBytes[MAGIC_LENGTH] = (byte) (compressMethod | compressionLevel);
	writeIntLE(compressedLength, outputBytes, MAGIC_LENGTH + 1);
	writeIntLE(len, outputBytes, MAGIC_LENGTH + 5);
	writeIntLE(check, outputBytes, MAGIC_LENGTH + 9);
	assert MAGIC_LENGTH + 13 == HEADER_LENGTH;

	outputBuf.writePosition(HEADER_LENGTH + compressedLength);

	return outputBuf;
}
 

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
private static ByteBuf readBody(LZ4FastDecompressor decompressor, StreamingXXHash32 checksum, Header header,
                                byte[] bytes, int off) throws ParseException {
	ByteBuf outputBuf = ByteBufPool.allocate(header.originalLen);
	outputBuf.writePosition(header.originalLen);
	switch (header.compressionMethod) {
		case COMPRESSION_METHOD_RAW:
			System.arraycopy(bytes, off, outputBuf.array(), 0, header.originalLen);
			break;
		case COMPRESSION_METHOD_LZ4:
			try {
				int compressedLen2 = decompressor.decompress(bytes, off, outputBuf.array(), 0, header.originalLen);
				if (header.compressedLen != compressedLen2) {
					throw new ParseException("Stream is corrupted");
				}
			} catch (LZ4Exception e) {
				throw new ParseException("Stream is corrupted", e);
			}
			break;
		default:
			throw new AssertionError();
	}
	checksum.reset();
	checksum.update(outputBuf.array(), 0, header.originalLen);
	if (checksum.getValue() != header.check) {
		throw new ParseException("Stream is corrupted");
	}
	return outputBuf;
}
 

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
public int getHash(final SimpleFeature feature) {
	this.startMeasuring();
	try {
		final int seed = 0x12af028e;
		StreamingXXHash32 hash32 = this.hashFactory.newStreamingHash32(seed);
		if (this.includeGeometry) {
			final Geometry geom = (Geometry) feature.getDefaultGeometry();
			if (geom != null) {
				final byte[] geomBytes = wkbWriter.write(geom);
				hash32.update(geomBytes, 0, geomBytes.length);
			}
		}
		
		final Iterator<String> attributeIt = this.includedAttributes.iterator();
		while (attributeIt.hasNext()) {
			final String attributeName = attributeIt.next();
			final Object value = feature.getAttribute(attributeName);
			if (value != null) {
				final byte[] valueBytes = value.toString().getBytes();
				hash32.update(valueBytes, 0, valueBytes.length);
			}
		}
		return hash32.getValue();
		
	} finally {
		this.stopMeasuring();
	}
}
 

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
private StreamLZ4Decompressor(LZ4FastDecompressor decompressor, StreamingXXHash32 checksum) {
	this.decompressor = decompressor;
	this.checksum = checksum;
	recreate();
}
 

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
public static StreamLZ4Decompressor create(LZ4FastDecompressor decompressor,
                                           StreamingXXHash32 checksum) {
	return new StreamLZ4Decompressor(decompressor, checksum);
}
 

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
private Output(LZ4FastDecompressor decompressor, StreamingXXHash32 checksum) {
	this.decompressor = decompressor;
	this.checksum = checksum;
}
 

import net.jpountz.xxhash.StreamingXXHash32; //导入依赖的package包/类
public static void main(String[] args) throws IOException {


        LZ4Factory factory = LZ4Factory.fastestInstance();
        byte[] data = "Compressors and decompressors are interchangeable: it is perfectly correct to compress with the JNI bindings and to decompress with a Java port, or the other way around.Compressors might not generate the same compressed streams on all platforms, especially if CPU endianness differs, but the compressed streams can be safely decompressed by any decompressor implementation on any platform.Compressors and decompressors are interchangeable: it is perfectly correct to compress with the JNI bindings and to decompress with a Java port, or the other way around.Compressors might not generate the same compressed streams on all platforms, especially if CPU endianness differs, but the compressed streams can be safely decompressed by any decompressor implementation on any platform.".getBytes("UTF-8");


        final int decompressedLength = data.length;
        System.out.println("dataLength:" + decompressedLength);

        // compress data
        LZ4Compressor compressor = factory.fastCompressor();
        int maxCompressedLength = compressor.maxCompressedLength(decompressedLength);
        byte[] compressed = new byte[maxCompressedLength];
        int compressedLength = compressor.compress(data, 0, decompressedLength, compressed, 0, maxCompressedLength);
        System.out.println("compressedLength:" + compressedLength);

     // decompress data
        // - method 1: when the decompressed length is known
        LZ4FastDecompressor decompressor = factory.fastDecompressor();
        byte[] restored = new byte[decompressedLength];
        int compressedLength2 = decompressor.decompress(compressed, 0, restored, 0, decompressedLength);
        // compressedLength == compressedLength2
        System.out.println("compressedLength2:" + compressedLength2);

        // - method 2: when the compressed length is known (a little slower)
        // the destination buffer needs to be over-sized
        LZ4SafeDecompressor decompressor2 = factory.safeDecompressor();
        int decompressedLength2 = decompressor2.decompress(compressed, 0, compressedLength, restored, 0);
        // decompressedLength == decompressedLength2
        System.out.println("decompressedLength2:" + compressedLength);



        XXHashFactory factory1 = XXHashFactory.fastestInstance();
        ByteArrayInputStream in = new ByteArrayInputStream(data);

        int seed = 0x9747b28c; // used to initialize the hash value, use whatever
        // value you want, but always the same
        StreamingXXHash32 hash32 = factory1.newStreamingHash32(seed);
        byte[] buf = new byte[8]; // for real-world usage, use a larger buffer, like 8192 bytes
        for (;;) {
            int read = in.read(buf);
            if (read == -1) {
                break;
            }
            hash32.update(buf, 0, read);
        }
        int hash = hash32.getValue();

        System.out.println(hash);
    }