org.ros.internal.message.StringResourceProvider.java Source code

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Here is the source code for org.ros.internal.message.StringResourceProvider.java

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/*
 * Copyright (C) 2011 Google Inc.
 *
 * 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.ros.internal.message;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;

import org.ros.exception.RosRuntimeException;

import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.util.Map;
import java.util.NoSuchElementException;

/**
 * @author damonkohler@google.com (Damon Kohler)
 */
public class StringResourceProvider {

    private final Map<String, String> cache;

    public StringResourceProvider() {
        cache = Maps.newConcurrentMap();
    }

    public String get(String resourceName) {
        if (!has(resourceName)) {
            throw new NoSuchElementException("Resource does not exist: " + resourceName);
        }
        if (!cache.containsKey(resourceName)) {
            InputStream in = getClass().getResourceAsStream(resourceName);
            StringBuilder out = new StringBuilder();
            Charset charset = Charset.forName("US-ASCII");
            byte[] buffer = new byte[8192];
            try {
                for (int bytesRead; (bytesRead = in.read(buffer)) != -1;) {
                    out.append(new String(buffer, 0, bytesRead, charset));
                }
            } catch (IOException e) {
                throw new RosRuntimeException("Failed to read resource: " + resourceName, e);
            }
            cache.put(resourceName, out.toString());
        }
        return cache.get(resourceName);
    }

    public boolean has(String resourceName) {
        return cache.containsKey(resourceName) || getClass().getResource(resourceName) != null;
    }

    public Map<String, String> getCachedStrings() {
        return ImmutableMap.copyOf(cache);
    }

    public void addStringToCache(String resourceName, String resourceContent) {
        cache.put(resourceName, resourceContent);
    }
}