org.sigmah.shared.servlet.URLs.java Source code

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Here is the source code for org.sigmah.shared.servlet.URLs.java

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package org.sigmah.shared.servlet;

/*
 * #%L
 * Sigmah
 * %%
 * Copyright (C) 2010 - 2016 URD
 * %%
 * 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/gpl-3.0.html>.
 * #L%
 */

import org.sigmah.client.util.ClientUtils;

import com.google.gwt.core.client.GWT;
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.RequestException;
import com.google.gwt.http.client.Response;
import com.google.gwt.user.client.rpc.AsyncCallback;

/**
 * URL utility methods.
 * 
 * @author Tom Miette (tmiette@ideia.fr)
 */
public final class URLs {

    private URLs() {
        // Provides only static methods.
    }

    /**
     * Checks if the given URL exist (using the HTTP GET method).
     * 
     * @param url
     *          The URL to test.
     * @param callback
     *          The callback.
     *          Available results (depending on the response status code):
     *          <ul>
     *          <li><strong>200</strong> : {@code AsyncCallback#onSuccess(true)};</li>
     *          <li><strong>404</strong> : {@code AsyncCallback#onSuccess(false)};</li>
     *          <li><strong>other</strong> : {@link AsyncCallback#onFailure(Throwable)};</li>
     *          </ul>
     */
    public static void checkURL(final String url, final AsyncCallback<Boolean> callback) {

        // Builds the request.
        final RequestBuilder requestBuilder = new RequestBuilder(RequestBuilder.GET, url);
        requestBuilder.setCallback(new RequestCallback() {

            @Override
            public void onResponseReceived(Request request, Response response) {

                // The URL exists.
                if (response.getStatusCode() == Response.SC_OK) {
                    callback.onSuccess(true);
                }
                // The URL doesn't exists.
                else if (response.getStatusCode() == Response.SC_NOT_FOUND) {
                    callback.onSuccess(false);
                }
                // Other errors.
                else {
                    callback.onFailure(null);
                }

            }

            @Override
            public void onError(Request request, Throwable exception) {
                callback.onFailure(exception);
            }

        });

        // Sends the request.
        try {
            requestBuilder.send();
        } catch (RequestException e) {
            callback.onFailure(e);
        }

    }

    /**
     * Builds and returns an URL for the current host page and the curren GWT module.
     * 
     * @param pathTokens
     *          The optional additional path tokens.
     * @return The URL.
     */
    public static String buildApplicationURL(String... pathTokens) {

        final StringBuilder sb = new StringBuilder();

        sb.append(GWT.getHostPageBaseURL());
        sb.append(GWT.getModuleName());
        sb.append("/");

        if (pathTokens != null && pathTokens.length > 0) {
            for (final String pathToken : pathTokens) {
                if (ClientUtils.isNotBlank(pathToken)) {
                    sb.append(pathToken);
                    sb.append("/");
                }
            }
        }

        // Removes the last slash.
        if (sb.charAt(sb.length() - 1) == '/') {
            sb.deleteCharAt(sb.length() - 1);
        }

        return sb.toString();

    }

}