com.sonicle.webtop.core.app.servlet.response.GZippableOutputStream.java Source code

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Here is the source code for com.sonicle.webtop.core.app.servlet.response.GZippableOutputStream.java

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/*
 * WebTop Services is a Web Application framework developed by Sonicle S.r.l.
 * Copyright (C) 2014 Sonicle S.r.l.
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License version 3 as published by
 * the Free Software Foundation with the addition of the following permission
 * added to Section 15 as permitted in Section 7(a): FOR ANY PART OF THE COVERED
 * WORK IN WHICH THE COPYRIGHT IS OWNED BY SONICLE, SONICLE DISCLAIMS THE
 * WARRANTY OF NON INFRINGEMENT OF THIRD PARTY RIGHTS.
 *
 * 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA.
 *
 * You can contact Sonicle S.r.l. at email address sonicle@sonicle.com
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License version 3.
 *
 * In accordance with Section 7(b) of the GNU Affero General Public License
 * version 3, these Appropriate Legal Notices must retain the display of the
 * Sonicle logo and Sonicle copyright notice. If the display of the logo is not
 * reasonably feasible for technical reasons, the Appropriate Legal Notices must
 * display the words "Copyright (C) 2014 Sonicle S.r.l.".
 */
package com.sonicle.webtop.core.app.servlet.response;

import com.sonicle.commons.web.ServletUtils;
import java.io.IOException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.zip.GZIPOutputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.lang3.StringUtils;

/**
 *
 * @author malbinola
 */
public class GZippableOutputStream extends ServletOutputStream {
    private final AtomicBoolean opened = new AtomicBoolean(true);
    protected HttpServletResponse response;
    protected ServletOutputStream outputStream;
    protected GZIPOutputStream gzipOutputStream;
    protected Boolean skipCompress = null;
    protected int gzipMinThreshold;
    protected byte[] buffer;
    protected int bufferCount = 0;
    protected int length = -1;

    public GZippableOutputStream(HttpServletResponse response) throws IOException {
        super();
        this.response = response;
        outputStream = response.getOutputStream();
    }

    public void setGzipMinThreshold(int gzipMinThreshold) {
        this.gzipMinThreshold = gzipMinThreshold;
        buffer = new byte[gzipMinThreshold];
    }

    protected boolean isSkipCompress() {
        if (skipCompress == null) {
            skipCompress = !ServletUtils.isCompressible(ServletUtils.getContentTypeHeader(response))
                    || StringUtils.containsIgnoreCase(response.getHeader("X-Skip-Compress"), "1");
        }
        return skipCompress;
    }

    @Override
    public boolean isReady() {
        return outputStream.isReady();
    }

    @Override
    public void setWriteListener(WriteListener writeListener) {
        outputStream.setWriteListener(writeListener);
    }

    @Override
    public void close() throws IOException {
        if (opened.compareAndSet(true, false)) {
            if (gzipOutputStream != null) {
                flushToGZip();
                gzipOutputStream.close();
                gzipOutputStream = null;
            } else if (bufferCount > 0) {
                outputStream.write(buffer, 0, bufferCount);
                bufferCount = 0;
            }
            outputStream.close();
        }
    }

    @Override
    public void flush() throws IOException {
        if (!opened.get())
            return;
        if (isSkipCompress())
            return;
        if (gzipOutputStream != null) {
            gzipOutputStream.flush();
        }
    }

    @Override
    public void write(int b) throws IOException {
        if (!opened.get())
            throw new IOException("Cannot write to a closed output stream");
        if (isSkipCompress()) {
            outputStream.write(b);
        } else {
            if (bufferCount >= buffer.length) {
                flushToGZip();
            }
            buffer[bufferCount++] = (byte) b;
        }
    }

    @Override
    public void write(byte[] b) throws IOException {
        write(b, 0, b.length);
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        if (!opened.get())
            throw new IOException("Cannot write to a closed output stream");
        if (isSkipCompress()) {
            outputStream.write(b, off, len);
        } else {
            if (len == 0)
                return;

            // Can we write into buffer ?
            if (len <= (buffer.length - bufferCount)) {
                System.arraycopy(b, off, buffer, bufferCount, len);
                bufferCount += len;
                return;
            }

            // There is not enough space in buffer. Flush it ...
            flushToGZip();

            // ... and try again. Note, that bufferCount = 0 here !
            if (len <= (buffer.length - bufferCount)) {
                System.arraycopy(b, off, buffer, bufferCount, len);
                bufferCount += len;
                return;
            }

            // write direct to gzip
            writeToGZip(b, off, len);
        }
    }

    protected void flushToGZip() throws IOException {
        if (bufferCount > 0) {
            writeToGZip(buffer, 0, bufferCount);
            bufferCount = 0;
        }
    }

    protected void writeToGZip(byte[] b, int off, int len) throws IOException {
        if (gzipOutputStream == null) {
            gzipOutputStream = new GZIPOutputStream(outputStream);
            ServletUtils.setCompressedContentHeader(response);
        }
        gzipOutputStream.write(b, off, len);
    }
}