Package nl.knaw.dans.bagit.hash

Class Hasher

java.lang.Object

nl.knaw.dans.bagit.hash.Hasher

public final class Hasher
extends Object

Convenience class for generating a HEX formatted string of the checksum hash.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	Hasher.ChunkResult	Represents the result of a chunk operation when processing data for hashing.
private static enum	Hasher.ChunkResultType
private static interface	Hasher.RetryableOperation<T>

Field Summary

Fields

Modifier and Type	Field	Description
private static final int	_64_KB
private static final int	CHUNK_SIZE
private static final String	CHUNK_SIZE_PROP
private static final long	DEFAULT_CHUNK_SIZE
private static final int	DEFAULT_MAX_RETRIES
private static final int	DEFAULT_RETRY_SLEEP_MS
private static final org.slf4j.Logger	logger
private static final String	MAX_RETRIES_PROP
private static final ResourceBundle	messages
private static final String	RETRY_SLEEP_MS_PROP

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Hasher()

Method Summary

Modifier and Type	Method	Description
private static void	addMessageDigestHashToManifest(Path path, Map<Manifest,MessageDigest> manifestToMessageDigestMap)
static Map<Manifest,MessageDigest>	createManifestToMessageDigestMap(Collection<SupportedAlgorithm> algorithms)	create a mapping between Manifest and MessageDigest for each each supplied SupportedAlgorithm
private static Hasher.ChunkResult	executeWithRetry(Hasher.RetryableOperation<Hasher.ChunkResult> operation, String description, int maxRetries, int retrySleepMs)
private static String	formatMessageDigest(MessageDigest messageDigest)
private static Hasher.ChunkResult	handlePartialContent(HttpURLConnection conn, MessageDigest messageDigest, long currentTotalSize)
static String	hash(URL url, MessageDigest messageDigest)	Create a HEX formatted string checksum hash of the data from the URL
static String	hash(URL url, MessageDigest messageDigest, Map<String,String> extraHeaders)	Create a HEX formatted string checksum hash of the data from the URL
static String	hash(Path path, MessageDigest messageDigest)	Create a HEX formatted string checksum hash of the file
static void	hash(Path path, Map<Manifest,MessageDigest> manifestToMessageDigestMap)	Update the Manifests with the file's hash
static String	hash(FetchItem item, MessageDigest messageDigest, Map<String,String> extraHeaders)	Create a HEX formatted string checksum hash of the data from the FetchItem
private static String	hashFullStream(URL url, MessageDigest messageDigest, Map<String,String> extraHeaders)
private static HttpURLConnection	openRangedConnection(URL url, String range, Map<String,String> extraHeaders)	Opens a HttpURLConnection for the given range.
private static int	updateDigestFromStream(InputStream is, MessageDigest messageDigest)	Reads from the InputStream and updates the MessageDigest.
(package private) static void	updateMessageDigests(Path path, Collection<MessageDigest> messageDigests)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

logger

private static final org.slf4j.Logger logger

_64_KB

private static final int _64_KB

See Also:

• Constant Field Values

CHUNK_SIZE

private static final int CHUNK_SIZE

See Also:

• Constant Field Values

messages

private static final ResourceBundle messages

CHUNK_SIZE_PROP

private static final String CHUNK_SIZE_PROP

See Also:

• Constant Field Values

MAX_RETRIES_PROP

private static final String MAX_RETRIES_PROP

See Also:

• Constant Field Values

RETRY_SLEEP_MS_PROP

private static final String RETRY_SLEEP_MS_PROP

See Also:

• Constant Field Values

DEFAULT_CHUNK_SIZE

private static final long DEFAULT_CHUNK_SIZE

See Also:

• Constant Field Values

DEFAULT_MAX_RETRIES

private static final int DEFAULT_MAX_RETRIES

See Also:

• Constant Field Values

DEFAULT_RETRY_SLEEP_MS

private static final int DEFAULT_RETRY_SLEEP_MS

See Also:

• Constant Field Values

Constructor Details

Hasher

private Hasher()

Method Details

hash

public static String hash(Path path,
 MessageDigest messageDigest)
                   throws IOException

Create a HEX formatted string checksum hash of the file

Parameters:

path - the Path (file) to hash

messageDigest - the MessageDigest object representing the hashing algorithm

Returns:

the hash as a hex formated string

Throws:

IOException - if there is a problem reading the file

hash

public static String hash(URL url,
 MessageDigest messageDigest)
                   throws IOException

Create a HEX formatted string checksum hash of the data from the URL

Parameters:

url - the URL to hash

messageDigest - the MessageDigest object representing the hashing algorithm

Returns:

the hash as a hex-formatted string

Throws:

IOException - if there is a problem reading from the URL

hash

public static String hash(FetchItem item,
 MessageDigest messageDigest,
 Map<String,String> extraHeaders)
                   throws IOException

Create a HEX formatted string checksum hash of the data from the FetchItem

Parameters:

item - the FetchItem to hash

messageDigest - the MessageDigest object representing the hashing algorithm

extraHeaders - optional extra headers to send with the request

Returns:

the hash as a hex formatted string

Throws:

IOException - if there is a problem reading from the URL

hashFullStream

private static String hashFullStream(URL url,
 MessageDigest messageDigest,
 Map<String,String> extraHeaders)
                              throws IOException

Throws:

IOException

hash

public static String hash(URL url,
 MessageDigest messageDigest,
 Map<String,String> extraHeaders)
                   throws IOException

Create a HEX formatted string checksum hash of the data from the URL

Parameters:

url - the URL to hash

messageDigest - the MessageDigest object representing the hashing algorithm

extraHeaders - optional extra headers to send with the request

Returns:

the hash as a hex formatted string

Throws:

IOException - if there is a problem reading from the URL

handlePartialContent

private static Hasher.ChunkResult handlePartialContent(HttpURLConnection conn,
 MessageDigest messageDigest,
 long currentTotalSize)
                                                throws IOException

Throws:

IOException

executeWithRetry

private static Hasher.ChunkResult executeWithRetry(Hasher.RetryableOperation<Hasher.ChunkResult> operation,
 String description,
 int maxRetries,
 int retrySleepMs)
                                            throws IOException

Throws:

IOException

openRangedConnection

private static HttpURLConnection openRangedConnection(URL url,
 String range,
 Map<String,String> extraHeaders)
                                               throws IOException

Opens a HttpURLConnection for the given range.

Throws:

IOException

updateDigestFromStream

private static int updateDigestFromStream(InputStream is,
 MessageDigest messageDigest)
                                   throws IOException

Reads from the InputStream and updates the MessageDigest. Returns the number of bytes read.

Throws:

IOException

hash

public static void hash(Path path,
 Map<Manifest,MessageDigest> manifestToMessageDigestMap)
                 throws IOException

Update the Manifests with the file's hash

Parameters:

path - the Path (file) to hash

manifestToMessageDigestMap - the map between Manifest and MessageDigest

Throws:

IOException - if there is a problem reading the file

updateMessageDigests

static void updateMessageDigests(Path path,
 Collection<MessageDigest> messageDigests)
                          throws IOException

Throws:

IOException

addMessageDigestHashToManifest

private static void addMessageDigestHashToManifest(Path path,
 Map<Manifest,MessageDigest> manifestToMessageDigestMap)

formatMessageDigest

private static String formatMessageDigest(MessageDigest messageDigest)

createManifestToMessageDigestMap

public static Map<Manifest,MessageDigest> createManifestToMessageDigestMap(Collection<SupportedAlgorithm> algorithms)
                                                                    throws NoSuchAlgorithmException

create a mapping between Manifest and MessageDigest for each each supplied SupportedAlgorithm

Parameters:

algorithms - the SupportedAlgorithm that you which to map to MessageDigest

Returns:

mapping between Manifest and MessageDigest

Throws:

NoSuchAlgorithmException - if MessageDigest doesn't support the algorithm