com.google.gwt.sample.healthyeatingapp.client.FacebookGraph.java Source code

Introduction

Here is the source code for com.google.gwt.sample.healthyeatingapp.client.FacebookGraph.java

Source

package com.google.gwt.sample.healthyeatingapp.client;

/*
Code taken and modified to this project's use from:
http://www.marcusschiesser.de/2013/01/using-the-facebook-graph-api-from-your-gwt-application/
*/
import java.io.IOException;

import com.google.api.gwt.oauth2.client.Auth;
import com.google.api.gwt.oauth2.client.AuthRequest;
import com.google.api.gwt.oauth2.client.Callback;
import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestBuilder;
import com.google.gwt.http.client.RequestBuilder.Method;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.RequestException;
import com.google.gwt.http.client.Response;
import com.google.gwt.json.client.JSONObject;
import com.google.gwt.json.client.JSONParser;

public class FacebookGraph {
    private String token = null;

    private static FacebookGraph staticObject = new FacebookGraph();

    private static final String FACEBOOK_AUTH_URL = "https://www.facebook.com/dialog/oauth";

    private static final String FACEBOOK_CLIENT_ID = "406630196123484";

    private FacebookGraph() {
    }

    public static FacebookGraph getStaticObject() {
        return staticObject;
    }

    public String getToken() {
        return token;
    }

    public void resetToken() {
        token = null;
    }

    private void RequestAuthorization(Callback<String, Throwable> callback) {
        final AuthRequest req = new AuthRequest(FACEBOOK_AUTH_URL, FACEBOOK_CLIENT_ID)
                .withScopes("email", "user_birthday")
                // Facebook expects a comma-delimited list of scopes
                .withScopeDelimiter(",");
        Auth.get().clearAllTokens();
        Auth.get().login(req, callback);
    }

    public void RequestAuthorizationAndQueryGraph(final String id, final Callback<JSONObject, Throwable> callback) {
        RequestAuthorizationAndQueryGraph(id, RequestBuilder.GET, null, callback);
    }

    public void RequestAuthorizationAndQueryGraph(final String id, final Method method, final String params,
            final Callback<JSONObject, Throwable> callback) {
        if (token == null) {
            RequestAuthorization(new Callback<String, Throwable>() {
                public void onSuccess(String token) {
                    FacebookGraph.this.token = token;
                    QueryGraph(id, method, params, callback);
                }

                public void onFailure(Throwable reason) {
                    callback.onFailure(reason);
                }
            });
        } else {
            QueryGraph(id, method, params, callback);
        }
    }

    private void QueryGraph(String id, Method method, String params,
            final Callback<JSONObject, Throwable> callback) {
        final String requestData = "access_token=" + token + (params != null ? "&" + params : "");
        RequestBuilder builder;
        if (method == RequestBuilder.POST) {
            builder = new RequestBuilder(method, "https://graph.facebook.com/" + id);
            builder.setHeader("Content-Type", "application/x-www-form-urlencoded");
        } else if (method == RequestBuilder.GET) {
            builder = new RequestBuilder(method, "https://graph.facebook.com/" + id + "?" + requestData);
        } else {
            callback.onFailure(new IOException("doGraph only supports GET and POST requests"));
            return;
        }
        try {
            builder.sendRequest(requestData, new RequestCallback() {
                public void onError(Request request, Throwable exception) {
                    callback.onFailure(exception);
                }

                public void onResponseReceived(Request request, Response response) {
                    if (Response.SC_OK == response.getStatusCode()) {
                        callback.onSuccess(JSONParser.parseStrict(response.getText()).isObject());
                    } else if (Response.SC_BAD_REQUEST == response.getStatusCode()) {
                        callback.onFailure(new IOException("Error: " + response.getText()));
                    } else {
                        callback.onFailure(
                                new IOException("Couldn't retrieve JSON (" + response.getStatusText() + ")"));
                    }
                }

            });
        } catch (RequestException e) {
            callback.onFailure(e);
        }
    }

}