com.medallia.spider.sttools.CachedTool.java Source code

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Here is the source code for com.medallia.spider.sttools.CachedTool.java

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/*
 * This file is part of the Spider Web Framework.
 * 
 * The Spider Web Framework is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * The Spider Web Framework 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 General Public License
 * along with the Spider Web Framework.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.medallia.spider.sttools;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

import com.google.common.hash.Hashing;
import org.antlr.stringtemplate.StringTemplate;

import com.medallia.spider.StaticResourceLookup;
import com.medallia.spider.StaticResources.StaticResource;

/**
 * Tool that is supposed to add a hash to a link to a static resource
 * to handle browser cache invalidation.
 * <p>
 * 
 * Note: not yet implemented, simply returns the link unmodified.
 *
 */
public class CachedTool implements StTool {

    private final StaticResourceLookup srl;

    public CachedTool(StaticResourceLookup srl) {
        this.srl = srl;
    }

    @Override
    public String render(StringTemplate st) {
        String resourceName = String.valueOf(st.getAttribute("it"));
        StaticResource sr = srl.findStaticResource(resourceName);

        if (sr != null) {
            // copy into buffer and calculate md5
            ByteArrayOutputStream buffer = new ByteArrayOutputStream();
            try {
                sr.copyTo(buffer);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }

            // create and return link
            String md5 = Hashing.md5().hashBytes(buffer.toByteArray()).toString();

            return resourceName + "?" + md5;
        }

        throw new RuntimeException("Resource not found: " + resourceName);
    }

}