rocket.remoting.client.support.rpc.JsonServiceMethodInvoker.java Source code

Introduction

Here is the source code for rocket.remoting.client.support.rpc.JsonServiceMethodInvoker.java

Source

/*
 * Copyright Miroslav Pokorny
 *
 * 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 rocket.remoting.client.support.rpc;

import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestBuilder;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.Response;
import com.google.gwt.json.client.JSONNull;
import com.google.gwt.json.client.JSONParser;
import com.google.gwt.json.client.JSONValue;
import com.google.gwt.user.client.rpc.AsyncCallback;

/**
 * The general base class for all json service stubs. Two sub-classes exist one
 * that handles POST and the other GET requests. The json response is
 * deserialized using the json serialization api, and then the given
 * AsyncCallback is invoked.
 * 
 * @author Miroslav Pokorny
 */
abstract public class JsonServiceMethodInvoker<R> extends RpcServiceMethodInvoker<R> implements RequestCallback {

    protected JsonServiceMethodInvoker() {
        super();
    }

    /**
     * Factory method which creates a new RequestBuilder.
     * 
     * @return A new RequestBuilder
     */
    @Override
    protected RequestBuilder createRequestBuilder() {
        return new RequestBuilder(this.getRequestMethod(), this.buildUrl());
    }

    /**
     * This method will be used to build a url for the request that is about to
     * be submitted.
     * 
     * @return The final url given to the RequestBuilder
     */
    abstract protected String buildUrl();

    /**
     * Takes the response and converts the json payload to a java instance using
     * {@link #deserializeJsonPayload(String)}
     * 
     * @param request
     *            The request
     * @param response
     *            The response
     */
    protected void onSuccessfulResponse(final Request request, final Response response) {
        final AsyncCallback<R> callback = this.getCallback();
        R object = null;
        boolean skipOnFailure = false;

        try {
            final String text = response.getText();
            final JSONValue jsonValue = JSONParser.parse(text);
            if (false == jsonValue.isNull() instanceof JSONNull) {
                object = this.readObject(jsonValue);
            }
            // invoke success! after deserializing...
            skipOnFailure = true;
            callback.onSuccess(object);

        } catch (final Throwable caught) {
            if (false == skipOnFailure) {
                // invoke failure if anything went wrong.
                callback.onFailure(caught);
            }
        }
    }

    /**
     * This method is implemented by the generator and acts a bridge calling GWT
     * to create a Serializer which will deserialize the incoming JSON stream
     * into a java object.
     * 
     * @param jsonValue
     *            The response from the json service.
     * @return The deserialized object
     */
    abstract protected R readObject(final JSONValue jsonValue);
}