Package org.apache.tika.language.detect

Class LanguageDetector

    • Field Detail

      • mixedLanguages

        protected boolean mixedLanguages

      • shortText

        protected boolean shortText

    • Constructor Detail

      • LanguageDetector

        public LanguageDetector()

    • Method Detail

      • getDefaultLanguageDetector

        public static LanguageDetector getDefaultLanguageDetector()

      • isMixedLanguages

        public boolean isMixedLanguages()

      • setMixedLanguages

        public LanguageDetector setMixedLanguages​(boolean mixedLanguages)

      • isShortText

        public boolean isShortText()

      • loadModels

        public abstract LanguageDetector loadModels()
                                     throws 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:
        IOException

      • loadModels

        public abstract LanguageDetector loadModels​(Set<String> languages)
                                     throws 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:
        IOException

      • hasModel

        public abstract boolean hasModel​(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​(Map<String,​Float> languageProbabilities)
                                    throws 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:
        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​(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 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.

      • detectAll

        public List<LanguageResult> detectAll​(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.