Java CRC32.update方法代码示例

import java.util.zip.CRC32; //导入方法依赖的package包/类
static long computeCrcOfCentralDir(RandomAccessFile raf, CentralDirectory dir)
        throws IOException {
    CRC32 crc = new CRC32();
    long stillToRead = dir.size;
    raf.seek(dir.offset);
    int length = (int) Math.min(BUFFER_SIZE, stillToRead);
    byte[] buffer = new byte[BUFFER_SIZE];
    length = raf.read(buffer, 0, length);
    while (length != -1) {
        crc.update(buffer, 0, length);
        stillToRead -= length;
        if (stillToRead == 0) {
            break;
        }
        length = (int) Math.min(BUFFER_SIZE, stillToRead);
        length = raf.read(buffer, 0, length);
    }
    return crc.getValue();
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
public static long getFileCRC(File file) throws IOException {
    BufferedInputStream bsrc = null;
    CRC32 crc = new CRC32();
    try {
        bsrc = new BufferedInputStream( new FileInputStream( file ) );
        byte[] bytes = new byte[1024];
        int i;
        while( (i = bsrc.read(bytes)) != -1 ) {
            crc.update(bytes, 0, i );
        }
    }
    finally {
        if ( bsrc != null ) {
            bsrc.close();
        }
    }
    return crc.getValue();
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
public static String CRC32(byte[] bArr) throws Throwable {
    CRC32 crc32 = new CRC32();
    crc32.update(bArr);
    long value = crc32.getValue();
    StringBuilder stringBuilder = new StringBuilder();
    stringBuilder.append(String.format("%02x", new Object[]{Integer.valueOf(((byte) ((int)
            (value >>> 56))) & 255)}));
    stringBuilder.append(String.format("%02x", new Object[]{Integer.valueOf(((byte) ((int)
            (value >>> 48))) & 255)}));
    stringBuilder.append(String.format("%02x", new Object[]{Integer.valueOf(((byte) ((int)
            (value >>> 40))) & 255)}));
    stringBuilder.append(String.format("%02x", new Object[]{Integer.valueOf(((byte) ((int)
            (value >>> 32))) & 255)}));
    stringBuilder.append(String.format("%02x", new Object[]{Integer.valueOf(((byte) ((int)
            (value >>> 24))) & 255)}));
    stringBuilder.append(String.format("%02x", new Object[]{Integer.valueOf(((byte) ((int)
            (value >>> 16))) & 255)}));
    stringBuilder.append(String.format("%02x", new Object[]{Integer.valueOf(((byte) ((int)
            (value >>> 8))) & 255)}));
    stringBuilder.append(String.format("%02x", new Object[]{Integer.valueOf(((byte) ((int)
            value)) & 255)}));
    while (stringBuilder.charAt(0) == '0') {
        stringBuilder = stringBuilder.deleteCharAt(0);
    }
    return stringBuilder.toString().toLowerCase();
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
private void writeString(ByteBuffer buffer, CRC32 crc32, String string) throws UnsupportedEncodingException
{
    char[] chars = string.toCharArray();
    byte[] bytes = new byte[chars.length];
    for (int i = 0; i < chars.length; i++)
    {
        if (chars[i] > 0xFF)
        {
            throw new UnsupportedEncodingException();
        }
        bytes[i] = (byte) chars[i];
    }
    buffer.putInt(bytes.length);
    buffer.put(bytes);
    crc32.update(bytes);
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
public static void main(String[] args) throws Exception {
    if (args.length == 0) {
      // Dump and use shared archive with different flag combinations
      dumpAndUseSharedArchive("+", "-");
      dumpAndUseSharedArchive("-", "+");
    } else {
      // Call intrinsified java.lang.Math::fma()
      Math.fma(1.0, 2.0, 3.0);

      byte[] buffer = new byte[256];
      // Call intrinsified java.util.zip.CRC32::update()
      CRC32 crc32 = new CRC32();
      crc32.update(buffer, 0, 256);

      // Call intrinsified java.util.zip.CRC32C::updateBytes(..)
      CRC32C crc32c = new CRC32C();
      crc32c.update(buffer, 0, 256);
    }
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
/**
 * Check if the CRC of the snapshot file matches the digest.
 * @param f The snapshot file object
 * @return The table list as a string
 * @throws IOException If CRC does not match
 */
public static String CRCCheck(File f) throws IOException {
    final FileInputStream fis = new FileInputStream(f);
    try {
        final BufferedInputStream bis = new BufferedInputStream(fis);
        ByteBuffer crcBuffer = ByteBuffer.allocate(4);
        if (4 != bis.read(crcBuffer.array())) {
            throw new EOFException("EOF while attempting to read CRC from snapshot digest");
        }
        final int crc = crcBuffer.getInt();
        final InputStreamReader isr = new InputStreamReader(bis, "UTF-8");
        CharArrayWriter caw = new CharArrayWriter();
        while (true) {
            int nextChar = isr.read();
            if (nextChar == -1) {
                throw new EOFException("EOF while reading snapshot digest");
            }
            if (nextChar == '\n') {
                break;
            }
            caw.write(nextChar);
        }
        String tableList = caw.toString();
        byte tableListBytes[] = tableList.getBytes("UTF-8");
        CRC32 tableListCRC = new CRC32();
        tableListCRC.update(tableListBytes);
        tableListCRC.update("\n".getBytes("UTF-8"));
        final int calculatedValue = (int)tableListCRC.getValue();
        if (crc != calculatedValue) {
            throw new IOException("CRC of snapshot digest did not match digest contents");
        }

        return tableList;
    } finally {
        try {
            if (fis != null)
                fis.close();
        } catch (IOException e) {}
    }
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
public ZioEntry( String name, String sourceDataFile)
    throws IOException
{
    zipInput = new ZipInput( sourceDataFile);
    filename = name;
    fileComment = "";
    this.compression = 0;
    this.size = (int)zipInput.getFileLength();
    this.compressedSize = this.size;

    if (getLogger().isDebugEnabled()) 
        getLogger().debug(String.format("Computing CRC for %s, size=%d",sourceDataFile,size));
    
    // compute CRC
    CRC32 crc = new CRC32();

    byte[] buffer = new byte[8096];

    int numRead = 0;
    while (numRead != size) {
        int count = zipInput.read( buffer, 0, Math.min( buffer.length, (this.size - numRead)));
        if (count > 0) {
            crc.update( buffer, 0, count);
            numRead += count;
        }
    }

    this.crc32 = (int)crc.getValue();

    zipInput.seek(0);
    this.dataPosition = 0;
    extraData = new byte[0];
    setTime( new File(sourceDataFile).lastModified());
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
long computeCRC(long minlength) {
    CRC32 crc = new CRC32();
    byte[] buffer = new byte[BUFFER_LEN];
    long count = getCount(minlength);
    for (long i = 0; i < count; i++) {
        crc.update(buffer);
    }
    return crc.getValue();
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
/**
 * 对输入字符串进行crc32散列返回int, 返回值有可能是负数.
 * 
 * Guava也有crc32实现, 但返回值无法返回long，所以统一使用JDK默认实现
 */
public static int crc32AsInt(@NotNull byte[] input) {
	CRC32 crc32 = new CRC32();
	crc32.update(input);
	// CRC32 只是 32bit int，为了CheckSum接口强转成long，此处再次转回来
	return (int) crc32.getValue();
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
public static DeflateResult deflate(ByteBuffer input) {
    byte[] inputBuf;
    int inputOffset;
    int inputLength = input.remaining();
    if (input.hasArray()) {
        inputBuf = input.array();
        inputOffset = input.arrayOffset() + input.position();
        input.position(input.limit());
    } else {
        inputBuf = new byte[inputLength];
        inputOffset = 0;
        input.get(inputBuf);
    }
    CRC32 crc32 = new CRC32();
    crc32.update(inputBuf, inputOffset, inputLength);
    long crc32Value = crc32.getValue();
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    Deflater deflater = new Deflater(9, true);
    deflater.setInput(inputBuf, inputOffset, inputLength);
    deflater.finish();
    byte[] buf = new byte[65536];
    while (!deflater.finished()) {
        int chunkSize = deflater.deflate(buf);
        out.write(buf, 0, chunkSize);
    }
    return new DeflateResult(inputLength, crc32Value, out.toByteArray());
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
public static long calc(File file) throws IOException {
    FileInputStream fis = new FileInputStream(file);
    int blockSize = 64 * 1024;
    byte[] buffer = new byte[blockSize];
    int read = 0;
    CRC32 crc32 = new CRC32();
    while ((read = fis.read(buffer, 0, buffer.length)) > 0) {
        crc32.update(buffer, 0, read);
    }
    return crc32.getValue();
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
@Test
public void testCrc32Checksum() throws IOException {
    CRC32 crc32 = new CRC32();
    crc32.update(TEST_DATA.getBytes());
    long expectedCRC32Checksum = crc32.getValue();
    Crc32ChecksumCalculatingInputStream crc32InputStream =
            new Crc32ChecksumCalculatingInputStream(new ByteArrayInputStream(TEST_DATA.getBytes()));
    while (crc32InputStream.read() != -1) {
        ;
    }
    assertEquals(expectedCRC32Checksum, crc32InputStream.getCrc32Checksum());
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
static public long crcForJar(String jarpath) throws IOException {
    InputStream fin = openJarFile(jarpath);
    if (fin == null)
        throw new FileNotFoundException();
    CRC32 crc = new CRC32();
    int b = -1;
    while ((b = fin.read()) != -1)
        crc.update(b);
    return crc.getValue();
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
private String readString(ByteBuffer buffer, CRC32 crc32) throws UnsupportedEncodingException
{
    int size = buffer.getInt();
    byte[] bytes = new byte[size];
    buffer.get(bytes);
    char[] chars = new char[size];
    for (int i = 0; i < size; i++)
    {
        chars[i] = (char) bytes[i];
    }
    crc32.update(bytes);
    return new String(chars);
}
 

import java.util.zip.CRC32; //导入方法依赖的package包/类
public static int crc32(ByteBuffer buf) {
    CRC32 checksum = new CRC32();
    while (buf.hasRemaining()) {
        checksum.update(buf.get());
    }
    return (int) checksum.getValue();
}