com.github.jknack.amd4j.ClasspathResourceLoader.java Source code

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Here is the source code for com.github.jknack.amd4j.ClasspathResourceLoader.java

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/**
 * Copyright (c) 2013 Edgar Espina
 *
 * This file is part of amd4j (https://github.com/jknack/amd4j)
 *
 * 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.github.jknack.amd4j;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.io.IOUtils;

/**
 * Resolve resource from classpath.
 *
 * @author edgar.espina
 * @since 0.1.0
 */
public class ClasspathResourceLoader implements ResourceLoader {

    /**
     * Handle {@link InputStream}.
     *
     * @author edgar.espina
     *
     * @param <V> The resulting value.
     */
    private interface StreamHandler<V> {

        /**
         * Handle an {@link InputStream}.
         *
         * @param in The {@link InputStream}.
         * @return A value.
         * @throws IOException If the stream cannot be handled.
         */
        V handle(InputStream in) throws IOException;
    }

    @Override
    public boolean exists(final ResourceURI uri) throws IOException {
        return process(uri, new StreamHandler<Boolean>() {
            @Override
            public Boolean handle(final InputStream in) throws IOException {
                return in != null;
            }
        });
    }

    @Override
    public String load(final ResourceURI uri) throws IOException {
        return process(uri, new StreamHandler<String>() {
            @Override
            public String handle(final InputStream in) throws IOException {
                if (in == null) {
                    throw new FileNotFoundException("classpath:" + uri);
                }
                return IOUtils.toString(in, "UTF-8");
            }
        });
    }

    /**
     * Resolve the uri to an {@link InputStream} and ask the handler to handle it.
     *
     * @param uri The resource uri.
     * @param handler The stream handler.
     * @param <V> The resulting value.
     * @return The resulting value.
     * @throws IOException If the file isn't found.
     */
    private <V> V process(final ResourceURI uri, final StreamHandler<V> handler) throws IOException {
        InputStream input = null;
        try {
            input = getClass().getResourceAsStream(uri.getPath());
            return handler.handle(input);
        } finally {
            IOUtils.closeQuietly(input);
        }
    }
}