org.helios.apmrouter.dataservice.json.marshalling.GSONJSONMarshaller.java Source code

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/**
 * Helios, OpenSource Monitoring
 * Brought to you by the Helios Development Group
 *
 * Copyright 2012, Helios Development Group and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org. 
 *
 */
package org.helios.apmrouter.dataservice.json.marshalling;

import java.lang.reflect.Type;
import java.net.SocketAddress;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArraySet;

import org.helios.apmrouter.OpCode;
import org.helios.apmrouter.server.ServerComponentBean;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.json.JSONObject;
import org.springframework.jmx.export.annotation.ManagedAttribute;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.TypeAdapterFactory;

/**
 * <p>Title: GSONJSONMarshaller</p>
 * <p>Description: JSON marshalling service, implemented using <a href="https://sites.google.com/site/gson/">Google-gson</a>to centralize the marshalling of outgoing objects into json.</p> 
 * <p>Company: Helios Development Group LLC</p>
 * @author Whitehead (nwhitehead AT heliosdev DOT org)
 * <p><code>org.helios.apmrouter.dataservice.json.marshalling.GSONJSONMarshaller</code></p>
 */

public class GSONJSONMarshaller extends ServerComponentBean implements JSONMarshaller {
    /** Sets the pretty-print attribute of the gson builder */
    protected boolean prettyPrint = false;
    /** Sets the HTML escaping attribute of the gson builder */
    protected boolean disableHtmlEscaping = false;
    /** Sets the null serialization attribute of the gson builder */
    protected boolean serializeNulls = false;

    /** Custom type adapters */
    protected final Map<Type, Object> adapterInstances = new ConcurrentHashMap<Type, Object>();
    /** Custom type adapter factories */
    protected final Set<TypeAdapterFactory> adapterFactoryInstances = new CopyOnWriteArraySet<TypeAdapterFactory>();

    /** The gson instance */
    protected Gson gson = null;

    /**
     * {@inheritDoc}
     * @see org.helios.apmrouter.dataservice.json.marshalling.JSONMarshaller#marshallToChannel(java.lang.Object)
     */
    public ChannelBuffer marshallToChannel(Object obj) {
        return marshallToChannel(null, obj);
    }

    /**
     * {@inheritDoc}
     * @see org.helios.apmrouter.dataservice.json.marshalling.JSONMarshaller#marshallToChannel(org.helios.apmrouter.OpCode, java.lang.Object)
     */
    public ChannelBuffer marshallToChannel(OpCode opCode, Object obj) {
        if (obj == null)
            return ChannelBuffers.buffer(0);
        byte[] bytes = null;
        if (obj instanceof CharSequence || obj instanceof JSONObject) {
            bytes = obj.toString().getBytes();
        } else {
            bytes = gson.toJson(obj).getBytes();
        }
        ChannelBuffer cb = ChannelBuffers.directBuffer(bytes.length + (opCode == null ? 0 : 5));
        if (opCode != null) {
            cb.writeByte(opCode.op());
            cb.writeInt(bytes.length);
        }
        cb.writeBytes(bytes);
        bytes = null;
        return cb;

    }

    /**
     * {@inheritDoc}
     * @see org.helios.apmrouter.dataservice.json.marshalling.JSONMarshaller#marshallToChannel(org.helios.apmrouter.OpCode, java.lang.Object, org.jboss.netty.channel.Channel)
     */
    public void marshallToChannel(OpCode op, Object obj, Channel channel) {
        channel.write(marshallToChannel(op, obj));
    }

    /**
     * {@inheritDoc}
     * @see org.helios.apmrouter.dataservice.json.marshalling.JSONMarshaller#marshallToChannel(java.lang.Object, org.jboss.netty.channel.Channel)
     */
    public void marshallToChannel(Object obj, Channel channel) {
        channel.write(marshallToChannel(null, obj));
    }

    /**
     * {@inheritDoc}
     * @see org.helios.apmrouter.dataservice.json.marshalling.JSONMarshaller#marshallToChannel(org.helios.apmrouter.OpCode, java.lang.Object, org.jboss.netty.channel.Channel, java.net.SocketAddress)
     */
    public void marshallToChannel(OpCode op, Object obj, Channel channel, SocketAddress sa) {
        channel.write(marshallToChannel(op, obj), sa == null ? channel.getRemoteAddress() : sa);
    }

    /**
     * {@inheritDoc}
     * @see org.helios.apmrouter.dataservice.json.marshalling.JSONMarshaller#marshallToChannel(java.lang.Object, org.jboss.netty.channel.Channel, java.net.SocketAddress)
     */
    public void marshallToChannel(Object obj, Channel channel, SocketAddress sa) {
        channel.write(marshallToChannel(null, obj), sa == null ? channel.getRemoteAddress() : sa);
    }

    /**
     * {@inheritDoc}
     * @see org.helios.apmrouter.dataservice.json.marshalling.JSONMarshaller#marshallToText(java.lang.Object)
     */
    public String marshallToText(Object obj) {
        if (obj == null)
            return "";
        if (obj instanceof CharSequence || obj instanceof JSONObject) {
            return obj.toString();
        }
        return gson.toJson(obj);
    }

    /**
     * {@inheritDoc}
     * @see org.helios.apmrouter.server.ServerComponentBean#doStart()
     */
    @Override
    protected void doStart() throws Exception {
        super.doStart();
        update();
    }

    /**
     * Creates a new Gson instance based on the settings in this bean.
     */
    protected void update() {
        GsonBuilder builder = new GsonBuilder();
        if (prettyPrint)
            builder.setPrettyPrinting();
        if (disableHtmlEscaping)
            builder.disableHtmlEscaping();
        if (!adapterInstances.isEmpty()) {
            for (Map.Entry<Type, Object> entry : adapterInstances.entrySet()) {
                builder.registerTypeAdapter(entry.getKey(), entry.getValue());
            }
        }
        if (!adapterFactoryInstances.isEmpty()) {
            for (TypeAdapterFactory taf : adapterFactoryInstances) {
                builder.registerTypeAdapterFactory(taf);
            }
        }
        gson = builder.create();
    }

    /**
     * Returns the pretty print attribute
     * @return the pretty print attribute
     */
    @ManagedAttribute(description = "The JSON pretty print attribute")
    public boolean isPrettyPrint() {
        return prettyPrint;
    }

    /**
     * Sets the pretty print attribute
     * @param prettyPrint true to pretty-print, false for compact 
     */
    @ManagedAttribute(description = "The JSON pretty print attribute")
    public void setPrettyPrint(boolean prettyPrint) {
        this.prettyPrint = prettyPrint;
        update();
    }

    /**
     * Returns the html escaping disabled attribute
     * @return true if html escaping is enabled, false if it disabled.
     */
    @ManagedAttribute(description = "The html escaping disabled attribute")
    public boolean isDisableHtmlEscaping() {
        return disableHtmlEscaping;
    }

    /**
     * Sets the html escaping disabled attribute
     * @param disableHtmlEscaping true to disable html escaping, false to enable
     */
    @ManagedAttribute(description = "The html escaping disabled attribute")
    public void setDisableHtmlEscaping(boolean disableHtmlEscaping) {
        this.disableHtmlEscaping = disableHtmlEscaping;
        update();
    }

    /**
     * Returns the serialize nulls attribute
     * @return true if nulls are being serialized, false otherwise
     */
    @ManagedAttribute(description = "The null serialization attribute")
    public boolean isSerializeNulls() {
        return serializeNulls;
    }

    /**
     * Sets the null serialization attribute
     * @param serializeNulls true to serialize nulls, false otherwise
     */
    @ManagedAttribute(description = "The null serialization attribute")
    public void setSerializeNulls(boolean serializeNulls) {
        this.serializeNulls = serializeNulls;
    }

    /**
     * Adds the passed map of adapter instances to the gson builder
     * @param adapterInstances the adapterInstances to set
     */
    public void setAdapterInstances(Map<Type, Object> adapterInstances) {
        this.adapterInstances.putAll(adapterInstances);
    }

    /**
     * Adds the passed set of adapter factory instances to the gson builder
     * @param adapterFactoryInstances the adapterFactoryInstances to set
     */
    public void setAdapterFactoryInstances(Set<TypeAdapterFactory> adapterFactoryInstances) {
        this.adapterFactoryInstances.addAll(adapterFactoryInstances);
    }

}