ThymeleafScriptEngine.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
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package org.apache.sling.scripting.thymeleaf.internal;

import java.io.Reader;
import java.io.Writer;
import java.util.Locale;

import javax.script.Bindings;
import javax.script.ScriptContext;
import javax.script.ScriptException;
import javax.servlet.ServletContext;

import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.scripting.SlingBindings;
import org.apache.sling.api.scripting.SlingScriptHelper;
import org.apache.sling.scripting.api.AbstractSlingScriptEngine;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.thymeleaf.context.IContext;

public final class ThymeleafScriptEngine extends AbstractSlingScriptEngine {

    private final ThymeleafScriptEngineFactory thymeleafScriptEngineFactory;

    private final Logger logger = LoggerFactory.getLogger(ThymeleafScriptEngine.class);

    public ThymeleafScriptEngine(final ThymeleafScriptEngineFactory thymeleafScriptEngineFactory) {
        super(thymeleafScriptEngineFactory);
        this.thymeleafScriptEngineFactory = thymeleafScriptEngineFactory;
    }

    @Override
    public Object eval(final Reader reader, final ScriptContext scriptContext) throws ScriptException {
        final Bindings bindings = scriptContext.getBindings(ScriptContext.ENGINE_SCOPE);
        final SlingScriptHelper helper = (SlingScriptHelper) bindings.get(SlingBindings.SLING);

        if (helper == null) {
            throw new ScriptException("SlingScriptHelper missing from bindings");
        }

        final SlingHttpServletRequest request = helper.getRequest();
        final SlingHttpServletResponse response = helper.getResponse();
        final ServletContext servletContext = null; // only used by Thymeleaf's ServletContextResourceResolver (TODO check if still true for 3.0)

        final Locale locale = helper.getResponse().getLocale();
        final String scriptName = helper.getScript().getScriptResource().getPath();
        final Writer writer = scriptContext.getWriter();

        try {
            final ResourceResolver resourceResolver = thymeleafScriptEngineFactory.getRequestScopedResourceResolver();
            final IContext context = new SlingWebContext(request, response, servletContext, resourceResolver, locale, bindings);
            thymeleafScriptEngineFactory.getTemplateEngine().process(scriptName, context, writer);
        } catch (Exception e) {
            logger.error("Failure rendering Thymeleaf template '{}': {}", scriptName, e.getMessage());
            throw new ScriptException(e);
        }

        return null;
    }

}