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/*
 * Copyright 2000,2005 wingS development team.
 *
 * This file is part of wingS (http://wingsframework.org).
 *
 * wingS 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 2.1
 * of the License, or (at your option) any later version.
 *
 * Please see COPYING for the complete licence.
 */
package org.wings.io;

import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.GZIPOutputStream;

/**
 * A Device encapsulating an OutputStream, compressing its
 * output. You can use this, if the browser states, that it can handle
 * compressed data; don't forget to set the appropriate header, then
 * (Content-Encoding).
 *
 * Override {@link DeviceFactory} and declare the updated factory in web.xml to use other devices.
 * Example Draft

 * String mimeType = extInfo.getMimeType();
 * // some browsers can handle a gziped stream only for text-files.
 * if (mimeType != null && mimeType.startsWith("text/")) {
 * String acceptEncoding = req.getHeader("Accept-Encoding");
 * int gzipPos;
 * if (acceptEncoding != null
 * && (gzipPos = acceptEncoding.indexOf("gzip")) >= 0) {
 * // some browsers send 'x-gzip', others just 'gzip'. Our
 * // response should be the same.
 * boolean isXGZip = (gzipPos >= 2
 * && acceptEncoding.charAt(gzipPos-1) == '-'
 * && acceptEncoding.charAt(gzipPos-2) == 'x');
 * response.addHeader("Content-Encoding",
 * (isXGZip ? "x-gzip" : "gzip"));
 * return new GZIPCompressingDevice(response.getOutputStream());
 * }
 * }
 * return new ServletDevice(response.getOutputStream());
 * }
 * 

 *
 * @author Henner Zeller
 */
public final class GZIPCompressingDevice implements Device {
    private final OutputStreamDevice deligee;

    public GZIPCompressingDevice(OutputStream out) throws IOException {
        deligee = new OutputStreamDevice(new GZIPOutputStream(out));
    }

    public GZIPCompressingDevice(Device d) throws IOException {
        this(new DeviceOutputStream(d));
    }

    /**
     * this returns false, since the compressing device is not size
     * preserving. Thats what is all about, right ?
     */
    @Override
    public boolean isSizePreserving() { return false; }

    // rest is just delegating..
    @Override
    public void flush() throws IOException {
        deligee.flush();
    }

    @Override
    public void close() throws IOException {
        deligee.close();
    }

    @Override
    public Device print(char c) throws IOException {
        deligee.print(c);
        return this;
    }

    @Override
    public Device print(char... c) throws IOException {
        deligee.print(c);
        return this;
    }

    @Override
    public Device print(char[] c, int start, int len) throws IOException {
        deligee.print(c, start, len);
        return this;
    }

    @Override
    public Device print(String s) throws IOException {
        deligee.print(s);
        return this;
    }

    @Override
    public Device print(int i) throws IOException {
        deligee.print(i);
        return this;
    }

    @Override
    public Device print(Object o) throws IOException {
        deligee.print(o);
        return this;
    }

    @Override
    public Device write(int c) throws IOException {
        deligee.write(c);
        return this;
    }

    @Override
    public Device write(byte... b) throws IOException {
        deligee.write(b);
        return this;
    }

    @Override
    public Device write(byte b[], int off, int len) throws IOException {
        deligee.write(b, off, len);
        return this;
    }
}