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package com.sun.mail.handlers;

import java.io.IOException;
import java.awt.datatransfer.DataFlavor;
import javax.activation.*;

/**
 * Base class for other DataContentHandlers.
 */
public abstract class handler_base implements DataContentHandler {

    /**
     * Return an array of ActivationDataFlavors that we support.
     * Usually there will be only one.
     *
     * @return	array of ActivationDataFlavors that we support
     */
    protected abstract ActivationDataFlavor[] getDataFlavors();

    /**
     * Given the flavor that matched, return the appropriate type of object.
     * Usually there's only one flavor so just call getContent.
     *
     * @param	aFlavor	the ActivationDataFlavor
     * @param	ds	DataSource containing the data
     * @return	the object
     * @exception	IOException	for errors reading the data
     */
    protected Object getData(ActivationDataFlavor aFlavor, DataSource ds)
				throws IOException {
	return getContent(ds);
    }

    /**
     * Return the DataFlavors for this <code>DataContentHandler</code>.
     *
     * @return The DataFlavors
     */
    @Override
    public DataFlavor[] getTransferDataFlavors() {
	ActivationDataFlavor[] adf = getDataFlavors();
	if (adf.length == 1)	// the common case
	    return new DataFlavor[] { adf[0] };
	DataFlavor[] df = new DataFlavor[adf.length];
	System.arraycopy(adf, 0, df, 0, adf.length);
	return df;
    }

    /**
     * Return the Transfer Data of type DataFlavor from InputStream.
     *
     * @param	df	The DataFlavor
     * @param	ds	The DataSource corresponding to the data
     * @return	the object
     * @exception	IOException	for errors reading the data
     */
    @Override
    public Object getTransferData(DataFlavor df, DataSource ds) 
			throws IOException {
	ActivationDataFlavor[] adf = getDataFlavors();
	for (int i = 0; i < adf.length; i++) {
	    // use ActivationDataFlavor.equals, which properly
	    // ignores Content-Type parameters in comparison
	    if (adf[i].equals(df))
		return getData(adf[i], ds);
	}
	return null;
    }
}
