Java File to InputStream openStream(final File file)

Description

Opens the given File to read it.

License

Open Source License

Parameter

Parameter	Description
file	File represents a file that should be opened to read

Exception

Parameter	Description
IOException	will be thrown if any I/O errors occur

Return

InputStream

Declaration

public static InputStream openStream(final File file) throws IOException 

Method Source Code

//package com.java2s;
/*/*  ww  w  .  j ava  2 s .  co  m*/
 * MIT License
 *
 * Copyright (c) 2016 EPAM Systems
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.List;
import java.util.zip.GZIPInputStream;

public class Main {
    /**
     * {@code List} specifies collection of file extensions that indicates that a file
     * with one of these extensions can be considered as compressed resource.
     */
    private static final List<String> GZIP_EXTENSIONS = Collections
            .unmodifiableList(Collections.singletonList(".gz"));

    /**
     * Opens the given {@code File} to read it. If file name indicates that it's compressed,
     * it's decompressed automatically.
     *
     * @param file {@code File} represents a file that should be opened to read
     * @return {@code InputStream}
     * @throws IOException will be thrown if any I/O errors occur
     */
    public static InputStream openStream(final File file) throws IOException {
        InputStream is = new FileInputStream(file);
        if (isGZIPFile(file.getName())) {
            return new GZIPInputStream(is);
        }
        return is;
    }

    /**
     * Returns <tt>true</tt> if and only if the given file name has en extension that indicates that
     * it's a GZIP resource, otherwise returns <tt>false</tt>.
     *
     * @param fn {@code String} represents a file name that should be tested
     * @return boolean
     */
    public static boolean isGZIPFile(final String fn) {
        for (String ext : GZIP_EXTENSIONS) {
            if (fn.endsWith(ext)) {
                return true;
            }
        }
        return false;
    }
}

Related

1. openInputStream(File file, boolean refuseEmpty)
2. openInputStream(String filePath)
3. openInputStream(String infilename)
4. openInputStream(String path)
5. openStream(final Class clazz, final String path)
6. openStream(InputStream in)