org.jboss.weld.environment.servlet.ExactListener Maven / Gradle / Ivy

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 * Copyright 2008, Red Hat Middleware LLC, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * 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 org.jboss.weld.environment.servlet;

import org.jboss.weld.environment.servlet.deployment.URLScanner;

import javax.servlet.ServletContext;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Set;

/**
 * Exact listener.
 * 
 * Explicitly list all the bean classes in bean-classes.txt file.
 * This will reduce scanning; e.g. useful for restricted env like GAE
 *
 * @author Ales Justin
 */
public class ExactListener extends Listener {
    public static final String BEAN_CLASSES = "bean-classes.txt";

    protected URLScanner createUrlScanner(ClassLoader classLoader, ServletContext context) {
        return new ExactScanner(classLoader, context);
    }

    private static class ExactScanner extends URLScanner {
        private ServletContext context;

        private ExactScanner(ClassLoader classLoader, ServletContext context) {
            super(classLoader);

            if (context == null) {
                throw new IllegalArgumentException("Null context");
            }

            this.context = context;
        }

        protected URL getExactBeansURL() {
            try {
                URL url = context.getResource("/WEB-INF/" + BEAN_CLASSES);
                if (url == null) {
                    url = getClassLoader().getResource(BEAN_CLASSES);
                }

                return url;
            } catch (MalformedURLException e) {
                throw new RuntimeException(e);
            }
        }

        @Override
        public void scanResources(String[] resources, Set classes, Set urls) {
            URL url = getExactBeansURL();
            if (url == null) {
                throw new IllegalArgumentException("Missing exact beans resource: " + BEAN_CLASSES);
            }

            try {
                InputStream is = url.openStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(is));
                try {
                    String line;
                    while ((line = reader.readLine()) != null) {
                        // ignore comments
                        if (!line.startsWith("#")) {
                            classes.add(line);
                        }
                    }
                } finally {
                    try {
                        is.close();
                    } catch (IOException ignore) {
                    }
                }
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    }
}