Java GZip InputStream Check isGZipped(InputStream in)

Description

is G Zipped

License

Apache License

Declaration

public static boolean isGZipped(InputStream in) 

Method Source Code

//package com.java2s;
/*//from ww w  . j  av a  2  s .co m
 * Copyright 2014 davidherod.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;

import java.io.RandomAccessFile;
import java.util.zip.GZIPInputStream;

public class Main {
    public static boolean isGZipped(InputStream in) {
        if (!in.markSupported()) {
            in = new BufferedInputStream(in);
        }
        in.mark(2);
        int magic = 0;
        try {
            magic = in.read() & 0xff | ((in.read() << 8) & 0xff00);
            in.reset();
        } catch (IOException e) {
            e.printStackTrace(System.err);
            return false;
        }
        return magic == GZIPInputStream.GZIP_MAGIC;
    }

    /**
     * Checks if a file is gzipped.
     *
     * @param f
     * @return
     */
    public static boolean isGZipped(File f) {
        int magic = 0;
        try {
            RandomAccessFile raf = new RandomAccessFile(f, "r");
            magic = raf.read() & 0xff | ((raf.read() << 8) & 0xff00);
            raf.close();
        } catch (Throwable e) {
            e.printStackTrace(System.err);
        }
        return magic == GZIPInputStream.GZIP_MAGIC;
    }
}

Related

1. isGZip(BufferedInputStream instream)
2. isGZIPCompressed(InputStream in)
3. isGZipped(InputStream in)
4. isGzipStm(InputStream in)