Package com.google.common.hash

Class AbstractNonStreamingHashFunction

java.lang.Object

com.google.common.hash.AbstractHashFunction

com.google.common.hash.AbstractNonStreamingHashFunction

All Implemented Interfaces:

HashFunction

Direct Known Subclasses:

FarmHashFingerprint64

abstract class AbstractNonStreamingHashFunction
extends AbstractHashFunction

Skeleton implementation of HashFunction, appropriate for non-streaming algorithms. All the hash computation done using newHasher() are delegated to the hashBytes(byte[], int, int) method.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private class	AbstractNonStreamingHashFunction.BufferingHasher	In-memory stream-based implementation of Hasher.
private static class	AbstractNonStreamingHashFunction.ExposedByteArrayOutputStream

Constructor Summary

Constructors

Constructor	Description
AbstractNonStreamingHashFunction()

Method Summary

Modifier and Type	Method	Description
abstract HashCode	hashBytes(byte[] input, int off, int len)	Shortcut for newHasher().putBytes(input, off, len).hash().
HashCode	hashBytes(java.nio.ByteBuffer input)	Shortcut for newHasher().putBytes(input).hash().
HashCode	hashInt(int input)	Shortcut for newHasher().putInt(input).hash(); returns the hash code for the given int value, interpreted in little-endian byte order.
HashCode	hashLong(long input)	Shortcut for newHasher().putLong(input).hash(); returns the hash code for the given long value, interpreted in little-endian byte order.
HashCode	hashString(java.lang.CharSequence input, java.nio.charset.Charset charset)	Shortcut for newHasher().putString(input, charset).hash().
HashCode	hashUnencodedChars(java.lang.CharSequence input)	Shortcut for newHasher().putUnencodedChars(input).hash().
Hasher	newHasher()	Begins a new hash code computation by returning an initialized, stateful Hasher instance that is ready to receive data.
Hasher	newHasher(int expectedInputSize)	Begins a new hash code computation as HashFunction.newHasher(), but provides a hint of the expected size of the input (in bytes).

Methods inherited from class com.google.common.hash.AbstractHashFunction

hashBytes, hashObject

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.google.common.hash.HashFunction

bits

Constructor Detail

AbstractNonStreamingHashFunction

AbstractNonStreamingHashFunction()

Method Detail

newHasher

public Hasher newHasher()

Description copied from interface: HashFunction

Begins a new hash code computation by returning an initialized, stateful Hasher instance that is ready to receive data. Example:

 HashFunction hf = Hashing.md5();
 HashCode hc = hf.newHasher()
     .putLong(id)
     .putBoolean(isActive)
     .hash();
 

newHasher

public Hasher newHasher(int expectedInputSize)

Description copied from interface: HashFunction

Begins a new hash code computation as HashFunction.newHasher(), but provides a hint of the expected size of the input (in bytes). This is only important for non-streaming hash functions (hash functions that need to buffer their whole input before processing any of it).

Specified by:

newHasher in interface HashFunction

Overrides:

newHasher in class AbstractHashFunction

hashInt

public HashCode hashInt(int input)

Description copied from interface: HashFunction

Shortcut for newHasher().putInt(input).hash(); returns the hash code for the given int value, interpreted in little-endian byte order. The implementation might perform better than its longhand equivalent, but should not perform worse.

Specified by:

hashInt in interface HashFunction

Overrides:

hashInt in class AbstractHashFunction

hashLong

public HashCode hashLong(long input)

Description copied from interface: HashFunction

Shortcut for newHasher().putLong(input).hash(); returns the hash code for the given long value, interpreted in little-endian byte order. The implementation might perform better than its longhand equivalent, but should not perform worse.

Specified by:

hashLong in interface HashFunction

Overrides:

hashLong in class AbstractHashFunction

hashUnencodedChars

public HashCode hashUnencodedChars(java.lang.CharSequence input)

Description copied from interface: HashFunction

Shortcut for newHasher().putUnencodedChars(input).hash(). The implementation might perform better than its longhand equivalent, but should not perform worse. Note that no character encoding is performed; the low byte and high byte of each char are hashed directly (in that order).

Warning: This method will produce different output than most other languages do when running the same hash function on the equivalent input. For cross-language compatibility, use HashFunction.hashString(java.lang.CharSequence, java.nio.charset.Charset), usually with a charset of UTF-8. For other use cases, use hashUnencodedChars.

Specified by:

hashUnencodedChars in interface HashFunction

Overrides:

hashUnencodedChars in class AbstractHashFunction

hashString

public HashCode hashString(java.lang.CharSequence input,
                           java.nio.charset.Charset charset)

Description copied from interface: HashFunction

Shortcut for newHasher().putString(input, charset).hash(). Characters are encoded using the given Charset. The implementation might perform better than its longhand equivalent, but should not perform worse.

Warning: This method, which reencodes the input before hashing it, is useful only for cross-language compatibility. For other use cases, prefer HashFunction.hashUnencodedChars(java.lang.CharSequence), which is faster, produces the same output across Java releases, and hashes every char in the input, even if some are invalid.

Specified by:

hashString in interface HashFunction

Overrides:

hashString in class AbstractHashFunction

hashBytes

public abstract HashCode hashBytes(byte[] input,
                                   int off,
                                   int len)

Description copied from interface: HashFunction

Shortcut for newHasher().putBytes(input, off, len).hash(). The implementation might perform better than its longhand equivalent, but should not perform worse.

Specified by:

hashBytes in interface HashFunction

Overrides:

hashBytes in class AbstractHashFunction

hashBytes

public HashCode hashBytes(java.nio.ByteBuffer input)

Description copied from interface: HashFunction

Shortcut for newHasher().putBytes(input).hash(). The implementation might perform better than its longhand equivalent, but should not perform worse.

Specified by:

hashBytes in interface HashFunction

Overrides:

hashBytes in class AbstractHashFunction