org.apache.tika.language.detect

Class LanguageDetector

java.lang.Object

org.apache.tika.language.detect.LanguageDetector

public abstract class LanguageDetector
extends java.lang.Object

Field Summary

Fields

Modifier and Type	Field and Description
private static ServiceLoader	DEFAULT_SERVICE_LOADER
protected boolean	mixedLanguages
protected boolean	shortText

Constructor Summary

Constructors

Constructor and Description
LanguageDetector()

Method Summary

Modifier and Type	Method and Description
abstract void	addText(char[] cbuf, int off, int len) Add statistics about this text for the current document.
void	addText(java.lang.CharSequence text) Add to the statistics being accumulated for the current document.
LanguageResult	detect()
LanguageResult	detect(java.lang.CharSequence text)
abstract java.util.List<LanguageResult>	detectAll() Detect languages based on previously submitted text (via addText calls).
java.util.List<LanguageResult>	detectAll(java.lang.String text) Utility wrapper that detects the language of a given chunk of text.
static LanguageDetector	getDefaultLanguageDetector()
static java.util.List<LanguageDetector>	getLanguageDetectors()
static java.util.List<LanguageDetector>	getLanguageDetectors(ServiceLoader loader)
boolean	hasEnoughText() Tell the caller whether more text is required for the current document before the language can be reliably detected.
abstract boolean	hasModel(java.lang.String language) Provide information about whether a model exists for a specific language.
boolean	isMixedLanguages()
boolean	isShortText()
abstract LanguageDetector	loadModels() Load (or re-load) all available language models.
abstract LanguageDetector	loadModels(java.util.Set<java.lang.String> languages) Load (or re-load) the models specified in .
abstract void	reset() Reset statistics about the current document being processed
LanguageDetector	setMixedLanguages(boolean mixedLanguages)
abstract LanguageDetector	setPriors(java.util.Map<java.lang.String,java.lang.Float> languageProbabilities) Set the a-priori probabilities for these languages.
LanguageDetector	setShortText(boolean shortText)

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_SERVICE_LOADER

private static final ServiceLoader DEFAULT_SERVICE_LOADER

mixedLanguages

protected boolean mixedLanguages

shortText

protected boolean shortText

Constructor Detail

LanguageDetector

public LanguageDetector()

Method Detail

getDefaultLanguageDetector

public static LanguageDetector getDefaultLanguageDetector()

getLanguageDetectors

public static java.util.List<LanguageDetector> getLanguageDetectors()

getLanguageDetectors

public static java.util.List<LanguageDetector> getLanguageDetectors(ServiceLoader loader)

isMixedLanguages

public boolean isMixedLanguages()

setMixedLanguages

public LanguageDetector setMixedLanguages(boolean mixedLanguages)

isShortText

public boolean isShortText()

setShortText

public LanguageDetector setShortText(boolean shortText)

loadModels

public abstract LanguageDetector loadModels()
                                     throws java.io.IOException

Load (or re-load) all available language models. This must be called after any settings that would impact the models being loaded (e.g. mixed language/short text), but before any of the document processing routines (below) are called. Note that it only needs to be called once.

Returns:

this

Throws:

java.io.IOException

loadModels

public abstract LanguageDetector loadModels(java.util.Set<java.lang.String> languages)
                                     throws java.io.IOException

Load (or re-load) the models specified in . These use the ISO 639-1 names, with an optional "-" for more specific specification (e.g. "zh-CN" for Chinese in China).

Parameters:

languages - list of target languages.

Returns:

this

Throws:

java.io.IOException

hasModel

public abstract boolean hasModel(java.lang.String language)

Provide information about whether a model exists for a specific language.

Parameters:

language - ISO 639-1 name for language

Returns:

true if a model for this language exists.

setPriors

public abstract LanguageDetector setPriors(java.util.Map<java.lang.String,java.lang.Float> languageProbabilities)
                                    throws java.io.IOException

Set the a-priori probabilities for these languages. The provided map uses the language as the key, and the probability (0.0 > probability < 1.0) of text being in that language. Note that if the probabilities don't sum to 1.0, these values will be normalized. If hasModel() returns false for any of the languages, an IllegalArgumentException is thrown. Use of these probabilities is detector-specific, and thus might not impact the results at all. As such, these should be viewed as a hint.

Parameters:

languageProbabilities - Map from language to probability

Returns:

this

Throws:

java.io.IOException

reset

public abstract void reset()

Reset statistics about the current document being processed

addText

public abstract void addText(char[] cbuf,
                             int off,
                             int len)

Add statistics about this text for the current document. Note that we assume an implicit word break exists before/after each of these runs of text.

Parameters:

cbuf - Character buffer

off - Offset into cbuf to first character in the run of text

len - Number of characters in the run of text.

addText

public void addText(java.lang.CharSequence text)

Add to the statistics being accumulated for the current document. Note that this is a default implementation for adding a string (not optimized)

Parameters:

text - Characters to add to current statistics.

hasEnoughText

public boolean hasEnoughText()

Tell the caller whether more text is required for the current document before the language can be reliably detected. Implementations can override this to do early termination of stats collection, which can improve performance with longer documents. Note that detect() can be called even when this returns false

Returns:

true if we have enough text for reliable detection.

detectAll

public abstract java.util.List<LanguageResult> detectAll()

Detect languages based on previously submitted text (via addText calls).

Returns:

list of all possible languages with at least medium confidence, sorted by confidence from highest to lowest. There will always be at least one result, which might have a confidence of NONE.

detect

public LanguageResult detect()

detectAll

public java.util.List<LanguageResult> detectAll(java.lang.String text)

Utility wrapper that detects the language of a given chunk of text.

Parameters:

text - String to add to current statistics.

Returns:

list of all possible languages with at least medium confidence, sorted by confidence from highest to lowest.

detect

public LanguageResult detect(java.lang.CharSequence text)