org.sonar.scanner.scan.filesystem.CharsetDetector.java Source code

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Here is the source code for org.sonar.scanner.scan.filesystem.CharsetDetector.java

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/*
 * SonarQube
 * Copyright (C) 2009-2017 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.scanner.scan.filesystem;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;

import javax.annotation.CheckForNull;

import org.apache.commons.io.ByteOrderMark;
import org.apache.commons.io.IOUtils;

public class CharsetDetector {
    private static final int BYTES_TO_DECODE = 4192;
    private Path filePath;
    private BufferedInputStream stream;
    private Charset detectedCharset;
    private Charset userEncoding;

    public CharsetDetector(Path filePath, Charset userEncoding) {
        this.filePath = filePath;
        this.userEncoding = userEncoding;
    }

    public boolean run() {
        try {
            byte[] buf = readBuffer();
            return detectCharset(buf);
        } catch (IOException e) {
            throw new IllegalStateException("Unable to read file " + filePath.toAbsolutePath().toString(), e);
        }
    }

    @CheckForNull
    public Charset charset() {
        assertRun();
        return detectedCharset;
    }

    public InputStream inputStream() {
        assertRun();
        return stream;
    }

    private byte[] readBuffer() throws IOException {
        stream = new BufferedInputStream(Files.newInputStream(filePath), BYTES_TO_DECODE * 2);
        stream.mark(BYTES_TO_DECODE);
        byte[] buf = new byte[BYTES_TO_DECODE];
        int read = IOUtils.read(stream, buf, 0, BYTES_TO_DECODE);
        stream.reset();
        stream.mark(-1);
        return Arrays.copyOf(buf, read);
    }

    private boolean detectCharset(byte[] buf) throws IOException {
        ByteCharsetDetector detector = new ByteCharsetDetector(new CharsetValidation(), userEncoding);
        ByteOrderMark bom = detector.detectBOM(buf);
        if (bom != null) {
            detectedCharset = Charset.forName(bom.getCharsetName());
            stream.skip(bom.length());
            return true;
        }

        detectedCharset = detector.detect(buf);
        return detectedCharset != null;
    }

    private void assertRun() {
        if (stream == null) {
            throw new IllegalStateException("Charset detection did not run");
        }
    }
}