15.3. Custom Text Extractors

package org.modeshape.jcr.api.text;

import javax.jcr.Node;
import javax.jcr.Property;
import javax.jcr.RepositoryException;

public abstract class TextExtractor {

    ...

    /**
     * Determine if this extractor is capable of processing content with the supplied MIME type.
     * @param mimeType the MIME type; never null
     * @return true if this extractor can process content with the supplied MIME type, or false otherwise.
     */
    public abstract boolean supportsMimeType( String mimeType );

    /**
     * Extract text from the given {@link Binary}, using the given output to record the results.
     * @param binary the binary value that can be used in the extraction process; never <code>null</code>
     * @param output the output from the sequencing operation; never <code>null</code>
     * @param context the context for the sequencing operation; never <code>null</code>
     * @throws Exception if there is a problem during the extraction process
     */
    public abstract void extractFrom( Binary binary,
                                      TextExtractor.Output output,
                                      Context context ) throws Exception;

    /**
     * Allows subclasses to process the stream of binary value property in "safe" fashion, making sure the stream is closed at the
     * end of the operation.
     * @param binary a {@link org.modeshape.jcr.api.Binary} who is expected to contain a non-null binary value.
     * @param operation a {@link org.modeshape.jcr.api.text.TextExtractor.BinaryOperation} which should work with the stream
     * @param <T> the return type of the binary operation
     * @return whatever type of result the stream operation returns
     * @throws Exception if there is an error processing the stream
     */
    protected final <T> T processStream( Binary binary,
                                         BinaryOperation<T> operation ) throws Exception {
        ...
    }

    /**
     * Interface which can be used by subclasses to process the input stream of a binary property.
     * @param <T> the return type of the binary operation
     */
    protected interface BinaryOperation<T> {
        T execute( InputStream stream ) throws Exception;
    }

    /**
     * Interface which provides additional information to the text extractors, during the extraction operation.
     */
    public interface Context {
        String mimeTypeOf( String name,
                           Binary binaryValue ) throws RepositoryException, IOException;
    }

    /**
     * The interface passed to a TextExtractor to which the extractor should record all text content.
     */
    public interface Output {
        /**
         * Record the text as being extracted. This method can be called multiple times during a single extract.
         * @param text the text extracted from the content.
         */
        void recordText( String text );
    }
}

package org.modeshape.jcr.api.text;

import javax.jcr.Node;
import javax.jcr.Property;
import javax.jcr.RepositoryException;

public abstract class TextExtractor {

    ...

    /**
     * Determine if this extractor is capable of processing content with the supplied MIME type.
     * @param mimeType the MIME type; never null
     * @return true if this extractor can process content with the supplied MIME type, or false otherwise.
     */
    public abstract boolean supportsMimeType( String mimeType );

    /**
     * Extract text from the given {@link Binary}, using the given output to record the results.
     * @param binary the binary value that can be used in the extraction process; never <code>null</code>
     * @param output the output from the sequencing operation; never <code>null</code>
     * @param context the context for the sequencing operation; never <code>null</code>
     * @throws Exception if there is a problem during the extraction process
     */
    public abstract void extractFrom( Binary binary,
                                      TextExtractor.Output output,
                                      Context context ) throws Exception;

    /**
     * Allows subclasses to process the stream of binary value property in "safe" fashion, making sure the stream is closed at the
     * end of the operation.
     * @param binary a {@link org.modeshape.jcr.api.Binary} who is expected to contain a non-null binary value.
     * @param operation a {@link org.modeshape.jcr.api.text.TextExtractor.BinaryOperation} which should work with the stream
     * @param <T> the return type of the binary operation
     * @return whatever type of result the stream operation returns
     * @throws Exception if there is an error processing the stream
     */
    protected final <T> T processStream( Binary binary,
                                         BinaryOperation<T> operation ) throws Exception {
        ...
    }

    /**
     * Interface which can be used by subclasses to process the input stream of a binary property.
     * @param <T> the return type of the binary operation
     */
    protected interface BinaryOperation<T> {
        T execute( InputStream stream ) throws Exception;
    }

    /**
     * Interface which provides additional information to the text extractors, during the extraction operation.
     */
    public interface Context {
        String mimeTypeOf( String name,
                           Binary binaryValue ) throws RepositoryException, IOException;
    }

    /**
     * The interface passed to a TextExtractor to which the extractor should record all text content.
     */
    public interface Output {
        /**
         * Record the text as being extracted. This method can be called multiple times during a single extract.
         * @param text the text extracted from the content.
         */
        void recordText( String text );
    }
}

public void extractFrom( final Binary binary,
                         final TextExtractor.Output output,
                         final Context context ) throws Exception {
    processStream(binary, new BinaryOperation<Object>() {
        @Override
        public Object execute( InputStream stream ) throws Exception {
            // Custom logic to read the stream and write to 'output'
            return null;
        }
    });
}

public void extractFrom( final Binary binary,
                         final TextExtractor.Output output,
                         final Context context ) throws Exception {
    processStream(binary, new BinaryOperation<Object>() {
        @Override
        public Object execute( InputStream stream ) throws Exception {
            // Custom logic to read the stream and write to 'output'
            return null;
        }
    });
}