com.evilco.license.server.encoder.CompressedLicenseEncoder.java Source code

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Here is the source code for com.evilco.license.server.encoder.CompressedLicenseEncoder.java

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/**
 * Copyright (C) 2014 Evil-Co <http://wwww.evil-co.com>
 *
 * 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.
 */
package com.evilco.license.server.encoder;

import com.evilco.license.common.ILicense;
import com.evilco.license.common.exception.LicenseEncoderException;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.io.BaseEncoding;
import org.apache.commons.io.IOUtils;

import javax.annotation.Nonnull;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;

/**
 * Provides a compressed text-based encoder.
 * @author         Johannes "Akkarin" Donath <johannesd@evil-co.com>
 * @copyright         Copyright (C) 2014 Evil-Co <http://www.evil-co.com>
 */
public class CompressedLicenseEncoder implements ILicenseEncoder<String> {

    /**
     * Defines the chunk width.
     */
    public static final int LICENSE_CHUNK_WIDTH = 80;

    /**
     * Stores the child encoder.
     */
    protected final ILicenseEncoder childEncoder;

    /**
     * Constructs a new CompressedLicenseEncoder.
     * @param encoder
     */
    public CompressedLicenseEncoder(ILicenseEncoder encoder) {
        this.childEncoder = encoder;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void encode(@Nonnull ILicense license, @Nonnull DataOutputStream outputStream)
            throws IOException, LicenseEncoderException {
        throw new UnsupportedOperationException(
                "Encoding compressed license representations into streams is not allowed.");
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String encode(@Nonnull ILicense license) throws LicenseEncoderException {
        // define streams
        ByteArrayOutputStream outputStream = null;
        GZIPOutputStream gzipOutputStream = null;
        DataOutputStream dataOutputStream = null;

        // encode data
        try {
            // create stream instances
            outputStream = new ByteArrayOutputStream();
            gzipOutputStream = new GZIPOutputStream(outputStream);
            dataOutputStream = new DataOutputStream(gzipOutputStream);

            // encode data
            this.childEncoder.encode(license, dataOutputStream);

            // flush buffers
            gzipOutputStream.flush();
            outputStream.flush();
        } catch (IOException ex) {
            throw new LicenseEncoderException(ex);
        } finally {
            IOUtils.closeQuietly(dataOutputStream);
            IOUtils.closeQuietly(gzipOutputStream);
            IOUtils.closeQuietly(outputStream);
        }

        // Encode Base64
        String licenseText = BaseEncoding.base64().encode(outputStream.toByteArray());

        // split text into chunks
        Joiner joiner = Joiner.on("\n").skipNulls();
        return joiner.join(Splitter.fixedLength(LICENSE_CHUNK_WIDTH).split(licenseText));
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isAvailable() {
        return this.childEncoder.isAvailable();
    }
}