org.restexpress.serialization.xml.XstreamXmlProcessor.java Source code

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Here is the source code for org.restexpress.serialization.xml.XstreamXmlProcessor.java

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/*
 * Copyright 2010, Strategic Gains, 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.restexpress.serialization.xml;

import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufInputStream;
import org.restexpress.ContentType;
import org.restexpress.Format;
import org.restexpress.common.util.StringUtils;
import org.restexpress.domain.JsendResultWrapper;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.converters.SingleValueConverter;

/**
 * The operation of these SerializationProcessor methods MUST match the behavior
 * of those in the DefaultJsonProcessor (and any other serialization processors).
 * 
 * @author toddf
 * @since Mar 16, 2010
 */
public class XstreamXmlProcessor extends XmlSerializationProcessor {
    private static final byte[] EMPTY_STRING_BYTES = StringUtils.EMPTY_STRING.getBytes(ContentType.CHARSET);

    private XStream xstream;
    private Map<Class<?>, String> aliases = new HashMap<Class<?>, String>();
    private boolean shouldAutoAlias = true;

    public XstreamXmlProcessor() {
        this(Format.XML);
    }

    public XstreamXmlProcessor(String format) {
        this(new XStream(), format);
        xstream.registerConverter(new XstreamTimestampConverter());
        xstream.alias("list", ArrayList.class);
        xstream.alias("response", JsendResultWrapper.class);
    }

    public XstreamXmlProcessor(XStream xstream, String format) {
        super(format);
        this.xstream = xstream;
        shouldAutoAlias = false;
    }

    protected XStream getXStream() {
        return this.xstream;
    }

    // SECTION: XML NAME ALIASING

    @Override
    public void alias(String name, Class<?> type) {
        xstream.alias(name, type);
    }

    public void registerConverter(SingleValueConverter converter) {
        xstream.registerConverter(converter);
    }

    // SECTION: SERIALIZATION PROCESSOR

    @Override
    public ByteBuffer serialize(Object object) {
        if (object == null) {
            return ByteBuffer.wrap(EMPTY_STRING_BYTES);
        }

        ByteArrayOutputStream b = new ByteArrayOutputStream();
        xstream.toXML(object, b);
        return ByteBuffer.wrap(b.toByteArray());
    }

    @Override
    @SuppressWarnings("unchecked")
    public <T> T deserialize(String xml, Class<T> type) {
        if (xml == null || xml.trim().isEmpty())
            return null;

        if (shouldAutoAlias) {
            addAliasIfNecessary(type);
        }

        return (T) xstream.fromXML(xml);
    }

    @Override
    @SuppressWarnings("unchecked")
    public <T> T deserialize(ByteBuf xml, Class<T> type) {
        if (!xml.isReadable())
            return null;

        return (T) xstream.fromXML(new ByteBufInputStream(xml));
    }

    private void addAliasIfNecessary(Class<?> type) {
        if (!aliases.containsKey(type)) {
            String name = type.getSimpleName().trim();

            if ("[]".equals(name) || "".equals(name)) {
                return;
            }

            xstream.alias(name, type);
        }
    }
}