elemental.js.util.Xhr.java Source code

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Here is the source code for elemental.js.util.Xhr.java

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/*
 * Copyright 2010 Google Inc.
 *
 * 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 elemental.js.util;

import com.google.gwt.core.client.JavaScriptException;
import com.google.gwt.xhr.client.ReadyStateChangeHandler;
import com.google.gwt.xhr.client.XMLHttpRequest;

import elemental.client.Browser;
import elemental.html.Window;

/**
 * A Simpler way to use {@link XMLHttpRequest}.
 */
public class Xhr {
    /**
     * Interface for getting notified when an XHR successfully completes, or
     * errors out.
     */
    public interface Callback {
        void onFail(XMLHttpRequest xhr);

        void onSuccess(XMLHttpRequest xhr);
    }

    private static class Handler implements ReadyStateChangeHandler {
        private final Callback callback;

        private Handler(Callback callback) {
            this.callback = callback;
        }

        public void onReadyStateChange(XMLHttpRequest xhr) {
            if (xhr.getReadyState() == XMLHttpRequest.DONE) {
                if (xhr.getStatus() == 200) {
                    callback.onSuccess(xhr);
                    xhr.clearOnReadyStateChange();
                    return;
                }
                callback.onFail(xhr);
                xhr.clearOnReadyStateChange();
            }
        }
    }

    /**
     * Send a GET request to the <code>url</code> and dispatch updates to the
     * <code>callback</code>.
     *
     * @param url
     * @param callback
     */
    public static void get(String url, Callback callback) {
        request(create(), "GET", url, callback);
    }

    /**
     * Send a GET request to the <code>url</code> and dispatch updates to the
     * <code>callback</code>.
     *
     * @param window the window object used to access the XMLHttpRequest
     *        constructor
     * @param url
     * @param callback
     */
    public static void get(Window window, String url, Callback callback) {
        request(create(window), "GET", url, callback);
    }

    /**
     * Send a HEAD request to the <code>url</code> and dispatch updates to the
     * <code>callback</code>.
     *
     * @param url
     * @param callback
     */
    public static void head(String url, Callback callback) {
        request(create(), "HEAD", url, callback);
    }

    /**
     * Send a HEAD request to the <code>url</code> and dispatch updates to the
     * <code>callback</code>.
     *
     * @param window the window object used to access the XMLHttpRequest
     *        constructor
     * @param url
     * @param callback
     */
    public static void head(Window window, String url, Callback callback) {
        request(create(window), "HEAD", url, callback);
    }

    /**
     * Send a POST request to the <code>url</code> and dispatch updates to the
     * <code>callback</code>.
     *
     * @param url
     * @param requestData the data to be passed to XMLHttpRequest.send
     * @param contentType a value for the Content-Type HTTP header
     * @param callback
     */
    public static void post(String url, String requestData, String contentType, Callback callback) {
        request(create(), "POST", url, requestData, contentType, callback);
    }

    /**
     * Send a POST request to the <code>url</code> and dispatch updates to the
     * <code>callback</code>.
     *
     * @param window the window object used to access the XMLHttpRequest
     *        constructor
     * @param url
     * @param requestData the data to be passed to XMLHttpRequest.send
     * @param contentType a value for the Content-Type HTTP header
     * @param callback
     */
    public static void post(Window window, String url, String requestData, String contentType, Callback callback) {
        request(create(window), "POST", url, requestData, contentType, callback);
    }

    private static XMLHttpRequest create() {
        return create(Browser.getWindow());
    }

    /**
     * Replacement for {@link XMLHttpRequest#create()} that allows better control
     * of which window object is used to access the XMLHttpRequest constructor.
     */
    private static native XMLHttpRequest create(Window window) /*-{
                                                               return new window.XMLHttpRequest();
                                                               }-*/;

    private static void request(XMLHttpRequest xhr, String method, String url, String requestData,
            String contentType, Callback callback) {
        try {
            xhr.setOnReadyStateChange(new Handler(callback));
            xhr.open(method, url);
            xhr.setRequestHeader("Content-type", contentType);
            xhr.send(requestData);
        } catch (JavaScriptException e) {
            // Just fail.
            callback.onFail(xhr);
            xhr.clearOnReadyStateChange();
        }
    }

    private static void request(XMLHttpRequest xhr, String method, String url, final Callback callback) {
        try {
            xhr.setOnReadyStateChange(new Handler(callback));
            xhr.open(method, url);
            xhr.send();
        } catch (JavaScriptException e) {
            // Just fail.
            callback.onFail(xhr);
            xhr.clearOnReadyStateChange();
        }
    }
}