ca.upei.ic.timetable.client.Service.java Source code

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Here is the source code for ca.upei.ic.timetable.client.Service.java

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/*
 *  Copyright 2008 University of Prince Edward Island
 *
 *  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 ca.upei.ic.timetable.client;

import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.json.client.JSONNumber;
import com.google.gwt.json.client.JSONObject;

/**
 * Provides services for controllers to get remote data
 * 
 * @author felix
 */
public class Service {

    private static Service instance_ = null;
    private static String DEFAULT_URL = getDefaultServiceURL();

    public static synchronized Service defaultInstance() {
        if (null == instance_) {
            instance_ = new Service(DEFAULT_URL);
        }

        return instance_;
    }

    private String url_;
    private Remote remote_;

    public Service(String url) {
        url_ = url;
        remote_ = new Remote(url_);
    }

    public void askCourseLevels(RequestCallback callback) {
        remote_.get("get_course_levels", null, callback);
    }

    public void askDepartments(RequestCallback callback) {
        remote_.get("get_departments", null, callback);
    }

    public void askCourses(String params, RequestCallback callback) {
        remote_.post("get_courses_of_departments_and_levels", "application/json", params, callback);
    }

    public void askSemesters(RequestCallback callback) {
        remote_.get("get_semesters", null, callback);
    }

    private Request currentCourseDetailRequest_;

    public void askCourseDetail(int courseId, RequestCallback callback) {
        JSONObject object = new JSONObject();
        object.put("id", new JSONNumber(courseId));
        currentCourseDetailRequest_ = remote_.post("get_course_detail", "application/json", object.toString(),
                callback);
    }

    public void cancelCourseDetailRequest() {
        if (currentCourseDetailRequest_ != null)
            currentCourseDetailRequest_.cancel();
    }

    public static native String getDefaultServiceURL() /*-{
                                                       return $wnd.__wi_CourseSelector_Service_URL;
                                                       }-*/;

}