com.ghusse.dolomite.flickr.Request.java Source code

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Here is the source code for com.ghusse.dolomite.flickr.Request.java

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/**
 * Copyright (c) Guillaume Gautreau 2011
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * @author guillaumegautreau
 */

package com.ghusse.dolomite.flickr;

import java.util.HashMap;
import com.google.gwt.json.client.JSONObject;
import java.util.Map;

import com.ghusse.dolomite.core.SignedJsonpRequestBuilder;
import com.google.gwt.jsonp.client.JsonpRequestBuilder;
import com.google.gwt.user.client.rpc.AsyncCallback;

/**
 * A request to the Flickr API.
 * 
 * @author guillaumegautreau
 * 
 * @param <T>
 *          Response type for this request.
 */
public abstract class Request<T extends Response> {
    /**
     * Flickr API url.
     */
    public static final String API_URL = "http://api.flickr.com/services/rest/";

    /**
     * Flickr API method that is called by this request.
     */
    private final String method;

    /**
     * Map of parameters/values sent as arguments of the request.
     */
    private final HashMap<String, String> additionalArguments = new HashMap<String, String>();

    /**
     * Credentials.
     */
    private final Credentials credentials;

    /**
     * Ctor.
     * 
     * @param flickrMethod
     *          Called method on Flickr API
     * @param connexionCredentials
     *          Credentials for calling this method
     */
    protected Request(final String flickrMethod, final Credentials connexionCredentials) {
        this.method = flickrMethod;
        this.credentials = connexionCredentials;
    }

    /**
     * Sends the request.
     * 
     * @param callback
     *          Callback object that will handle the result.
     * @param args
     *          Map of arguments for this request.
     */
    protected void send(final AsyncCallback<T> callback, final Map<String, String> args) {
        args.put("method", this.method);
        args.put("format", "json");
        this.credentials.putParams(args);

        args.putAll(this.additionalArguments);

        if (this.credentials.isSigned()) {
            this.sendSignedRequest(callback, args);
        } else {
            this.sendUnsignedRequest(callback, args);
        }
    }

    /**
     * Sends the request without any other argument.
     * 
     * @param callback
     *          Callback object that will handle the result.
     */
    public void send(final AsyncCallback<T> callback) {
        this.send(callback, new HashMap<String, String>());
    }

    /**
     * Arguments of this instance.
     * @return Arguments for this request.
     */
    protected HashMap<String, String> getArguments() {
        return this.additionalArguments;
    }

    /**
     * Sets an argument value.
     * @param key     Argument
     * @param value   Value
     */
    protected final void setArgument(final String key, final String value) {
        this.additionalArguments.put(key, value);
    }

    /**
     * Gets the argument value.
     * @param key Argument name.
     * @return    Arg value.
     */
    public final String getArgument(final String key) {
        return this.additionalArguments.get(key);
    }

    /**
     * Sends an unsigned request.
     * @param callback    Callback object.
     * @param args        Request arguments.
     */
    protected void sendUnsignedRequest(final AsyncCallback<T> callback, final Map<String, String> args) {
        JsonpRequestBuilder jsonp = new JsonpRequestBuilder();
        jsonp.setCallbackParam("jsoncallback");

        boolean first = true;
        StringBuilder uri = new StringBuilder(API_URL);
        for (Map.Entry<String, String> entry : args.entrySet()) {
            uri.append(first ? "?" : "&");
            first = false;
            uri.append(entry.getKey());
            uri.append("=");
            uri.append(entry.getValue());
        }

        jsonp.requestObject(uri.toString(), new AsyncCallback<T>() {
            @Override
            public void onFailure(final Throwable caught) {
                callback.onFailure(caught);
            }

            @Override
            public void onSuccess(final T result) {
                if (result == null) {
                    callback.onFailure(new NullResultException());
                } else if (!result.getStatus()) {
                    callback.onFailure(new FlickrException(result.getCode(), new JSONObject(result).toString()));
                } else {
                    callback.onSuccess(result);
                }
            }

        });
    }

    /**
     * Sends a signed request.
     * @param callback    Callback object
     * @param args        Request arguments
     */
    protected void sendSignedRequest(final AsyncCallback<T> callback, final Map<String, String> args) {
        SignedJsonpRequestBuilder jsonp = new SignedJsonpRequestBuilder();
        jsonp.setCallbackParam("jsoncallback");
        jsonp.requestObject(Request.API_URL, args, ((SignedCredentials) this.getCredentials()).getSecret(),
                new AsyncCallback<T>() {

                    @Override
                    public void onFailure(final Throwable caught) {
                        callback.onFailure(caught);
                    }

                    @Override
                    public void onSuccess(final T result) {
                        if (result == null) {
                            callback.onFailure(new NullResultException());
                        } else if (!result.getStatus()) {
                            callback.onFailure(new FlickrException(result.getCode(), result.getMessage()));
                        } else {
                            callback.onSuccess(result);
                        }
                    }

                });
    }

    /**
     * Gets the credentials for this request.
     * @return    Credentials.
     */
    protected Credentials getCredentials() {
        return this.credentials;
    }
}