com.datatorrent.stram.StringCodecs.java Source code

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Here is the source code for com.datatorrent.stram.StringCodecs.java

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/**
 * 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.
 */
package com.datatorrent.stram;

import java.net.URI;
import java.util.concurrent.ConcurrentHashMap;
import java.util.HashMap;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;

import com.datatorrent.api.StringCodec;
import com.datatorrent.netlet.util.DTThrowable;

/**
 * <p>StringCodecs class.</p>
 *
 * @since 0.9.4
 */
public class StringCodecs {
    private static final ConcurrentHashMap<ClassLoader, Boolean> classLoaders = new ConcurrentHashMap<ClassLoader, Boolean>();
    private static final Map<Class<?>, Class<? extends StringCodec<?>>> codecs = new HashMap<Class<?>, Class<? extends StringCodec<?>>>();
    private static final Logger LOG = LoggerFactory.getLogger(StringCodecs.class);

    private StringCodecs() {
        // no creation of instances
    }

    public static void loadDefaultConverters() {
        LOG.debug("Loading default converters for BeanUtils");
        ConvertUtils.register(new Converter() {
            @Override
            @SuppressWarnings("unchecked")
            public Object convert(Class type, Object value) {
                if (value == null) {
                    return null;
                }
                for (Class<?> clazz = value.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
                    Class<? extends StringCodec> codec = codecs.get(clazz);
                    if (codec == null) {
                        continue;
                    }

                    StringCodec instance;
                    try {
                        instance = codec.newInstance();
                    } catch (IllegalAccessException ex) {
                        throw new RuntimeException(
                                "Internal Error - it's impossible for this exception to be thrown!", ex);
                    } catch (InstantiationException ex) {
                        throw new RuntimeException(
                                "Internal Error - it's impossible for this exception to be thrown!", ex);
                    }

                    return instance.toString(value);
                }

                return value.toString();
            }

        }, String.class);

        ConvertUtils.register(new Converter() {
            @Override
            public Object convert(Class type, Object value) {
                return value == null ? null : URI.create(value.toString());
            }
        }, URI.class);
    }

    public static void clear() {
        for (Map.Entry<Class<?>, Class<? extends StringCodec<?>>> entry : codecs.entrySet()) {
            ConvertUtils.deregister(entry.getKey());
        }
        codecs.clear();
    }

    public static void loadConverters(Map<Class<?>, Class<? extends StringCodec<?>>> map) {
        check();
        if (map == null) {
            return;
        }
        for (Map.Entry<Class<?>, Class<? extends StringCodec<?>>> entry : map.entrySet()) {
            try {
                register(entry.getValue(), entry.getKey());
            } catch (Exception ex) {
                DTThrowable.rethrow(ex);
            }
        }
    }

    public static void check() {
        if (classLoaders.putIfAbsent(Thread.currentThread().getContextClassLoader(), Boolean.TRUE) == null) {
            loadDefaultConverters();
            for (Map.Entry<Class<?>, Class<? extends StringCodec<?>>> entry : codecs.entrySet()) {
                try {
                    final StringCodec<?> codecInstance = entry.getValue().newInstance();
                    ConvertUtils.register(new Converter() {
                        @Override
                        public Object convert(Class type, Object value) {
                            return value == null ? null : codecInstance.fromString(value.toString());
                        }

                    }, entry.getKey());
                } catch (Exception ex) {
                    throw new RuntimeException(ex);
                }
            }
        }
    }

    public static <T> void deregister(Class<T> clazz) {
        ConvertUtils.deregister(clazz);
        codecs.remove(clazz);
    }

    public static <T> void register(final Class<? extends StringCodec<?>> codec, final Class<T> clazz)
            throws InstantiationException, IllegalAccessException {
        check();
        final StringCodec<?> codecInstance = codec.newInstance();
        ConvertUtils.register(new Converter() {
            @Override
            public Object convert(Class type, Object value) {
                return value == null ? null : codecInstance.fromString(value.toString());
            }

        }, clazz);
        codecs.put(clazz, codec);
    }

}