org.gatein.management.rest.providers.JsonResourceProvider.java Source code

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Here is the source code for org.gatein.management.rest.providers.JsonResourceProvider.java

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/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2011, Red Hat, Inc., 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.gatein.management.rest.providers;

import org.gatein.management.rest.content.Child;
import org.gatein.management.rest.content.Link;
import org.gatein.management.rest.content.Operation;
import org.gatein.management.rest.content.Resource;
import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONWriter;

import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * JSON Provider to control marshalling of a managed resource.
 *
 * @author <a href="mailto:nscavell@redhat.com">Nick Scavelli</a>
 * @version $Revision$
 */
@Provider
@Produces(MediaType.APPLICATION_JSON)
public class JsonResourceProvider implements MessageBodyWriter<Resource> {
    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return (Resource.class.isAssignableFrom(type));
    }

    @Override
    public long getSize(Resource resource, Class<?> type, Type genericType, Annotation[] annotations,
            MediaType mediaType) {
        return -1;
    }

    @Override
    public void writeTo(Resource resource, Class<?> type, Type genericType, Annotation[] annotations,
            MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
            throws IOException, WebApplicationException {
        PrintWriter printWriter = new PrintWriter(entityStream);
        try {
            JSONWriter writer = new JSONWriter(printWriter);
            writer.object().key("description").value(resource.getDescription());
            writer.key("children").array();
            for (Child child : resource.getChildren()) {
                writeChild(child, writer);
            }
            writer.endArray();
            if (resource.getOperations() != null) {
                writer.key("operations").array();
                for (Operation operation : resource.getOperations()) {
                    writeOperation(operation, writer);
                }
                writer.endArray();
            }
            writer.endObject();

            printWriter.flush();
        } catch (JSONException e) {
            throw new IOException("Exception writing json result.", e);
        } finally {
            printWriter.close();
        }
    }

    private void writeOperation(Operation operation, JSONWriter writer) throws IOException, JSONException {
        writer.object().key("operation-name").value(operation.getOperationName());
        writer.key("operation-description").value(operation.getOperationDescription());
        writeLink("link", operation.getOperationLink(), writer);
        writer.endObject();
    }

    private void writeChild(Child child, JSONWriter writer) throws IOException, JSONException {
        writer.object().key("name").value(child.getName());
        writer.key("description").value(child.getDescription());
        writeLink("link", child.getLink(), writer);
        writer.endObject();
    }

    private void writeLink(String name, Link link, JSONWriter writer) throws IOException, JSONException {
        writer.key(name).object();
        if (link.getRel() != null) {
            writer.key("rel").value(link.getRel());
        }
        writer.key("href").value(link.getHref());

        if (link.getType() != null) {
            writer.key("type").value(link.getType());
        }
        if (link.getMethod() != null) {
            writer.key("method").value(link.getMethod());
        }
        writer.endObject();
    }
}