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An utility library for spring-based web-services for compressing / optimizing JS and CSS resources.
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/**
 * Copyright 2012 the project-owners
 *
 *    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 inti.ws.spring.resource;

import inti.ws.spring.resource.config.ConfigParserSettings;

import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;

import javax.activation.MimetypesFileTypeMap;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.codec.binary.Hex;
import org.apache.commons.io.IOUtils;
import org.apache.http.HttpHeaders;

/**
 * The ByteResource mainly represents files of any kind. ByteReresources are not minified at all and will never change
 * it's content.
 */
public class ByteWebResource extends WebResource {

    /**
     * The content.
     */
    protected byte[] bytes;
    /**
     * The contentType / MIME-Type.
     */
    protected String contentType;

    public ByteWebResource(ServletContext ctx, String location, String route) throws Exception {
        super(ctx, location, route, null, false);

        contentType = MimetypesFileTypeMap.getDefaultFileTypeMap().getContentType(location);
        update();
    }

    /**
     * Always returns false.
     */
    @Override
    public boolean hasChanged() throws IOException {
        return false;
    }

    /**
     * Always returns false.
     */
    @Override
    public boolean updateIfNeeded() throws IOException, Exception {
        return false;
    }

    /**
     * Reads the file and stores it's content.
     */
    @Override
    public void update() throws Exception {
        StringBuilder builder = new StringBuilder(32);
        MessageDigest digest = DIGESTS.get();
        InputStream inputStream = resource.getInputStream();

        try {
            lastModified = resource.lastModified();
            bytes = IOUtils.toByteArray(inputStream);
        } finally {
            inputStream.close();
        }

        digest.reset();
        builder.append(Hex.encodeHexString(digest.digest(bytes)));
        messageDigest = builder.toString();
        builder.delete(0, builder.length());

        DATE_FORMATTER.formatDate(lastModified, builder);
        lastModifiedString = builder.toString();
    }

    /**
     * Sets the MIME-Type as contentType.
     */
    @Override
    public void processResponse(HttpServletRequest request, HttpServletResponse response, ConfigParserSettings settings) {
        super.processResponse(request, response, settings);

        if (contentType != null) {
            response.setHeader(HttpHeaders.CONTENT_TYPE, contentType);
        }
    }

    @Override
    public byte[] getByteContent(ConfigParserSettings settings) {
        return bytes;
    }

}