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SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by downstream projects in the SciJava ecosystem, such as ImageJ and SCIFIO.

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/*
 * #%L
 * SciJava Common shared library for SciJava software.
 * %%
 * Copyright (C) 2009 - 2017 Board of Regents of the University of
 * Wisconsin-Madison, Broad Institute of MIT and Harvard, Max Planck
 * Institute of Molecular Cell Biology and Genetics, University of
 * Konstanz, and KNIME GmbH.
 * %%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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package org.scijava.io.handle;

import java.io.IOException;
import java.util.Objects;

import org.scijava.io.IOService;
import org.scijava.io.location.Location;
import org.scijava.plugin.WrapperService;
import org.scijava.service.SciJavaService;

/**
 * Interface for low-level data I/O: reading and writing bytes using
 * {@link DataHandle}s.
 * 
 * @author Curtis Rueden
 * @see IOService
 * @see Location
 */
public interface DataHandleService extends
	WrapperService>, SciJavaService
{

	// -- PTService methods --

	@Override
	@SuppressWarnings({ "rawtypes", "unchecked" })
	default Class> getPluginType() {
		return (Class) DataHandle.class;
	}

	// -- Typed methods --

	@Override
	default Class getType() {
		return Location.class;
	}

	/**
	 * Convenience method to test whether it describes an existing file.
	 *
	 * @param location the location to test
	 * @return The result of {@link DataHandle#exists()} on a newly created handle
	 *         on this location
	 * @throws IOException
	 */
	default boolean exists(final Location location) throws IOException {
		try (DataHandle handle = create(location)) {
			return handle.exists();
		}
	}

	/**
	 * Wraps the provided {@link DataHandle} in a read-only buffer for accelerated
	 * reading.
	 *
	 * @param handle the handle to wrap
	 * @see ReadBufferDataHandle#ReadBufferDataHandle(DataHandle)
	 */
	default DataHandle readBuffer(final DataHandle handle) {
		Objects.nonNull(handle);
		return new ReadBufferDataHandle(handle);
	}

	/**
	 * Creates a {@link DataHandle} on the provided {@link Location} wrapped in a
	 * read-only buffer for accelerated reading.
	 *
	 * @param location the handle to wrap
	 * @see ReadBufferDataHandle#ReadBufferDataHandle(DataHandle)
	 */
	default DataHandle readBuffer(final Location location) {
		final DataHandle handle = create(location);
		return handle == null ? null : new ReadBufferDataHandle(handle);
	}

	/**
	 * Wraps the provided {@link DataHandle} in a write-only buffer for
	 * accelerated writing.
	 *
	 * @param handle the handle to wrap
	 * @see WriteBufferDataHandle#WriteBufferDataHandle(DataHandle)
	 */
	default DataHandle writeBuffer(final DataHandle handle) {
		Objects.nonNull(handle);
		return new WriteBufferDataHandle(handle);
	}
}