/*
* Copyright 2009 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 com.google.gwt.core.client.impl;
import com.google.gwt.core.client.impl.AsyncFragmentLoader.HttpDownloadFailure;
import com.google.gwt.core.client.impl.LoadingStrategyBase.RequestData;
/**
* A download strategy that uses XHRs and iss therefore not cross site compatible.
*
* This is the default strategy for the IframeLinker.
*/
public class XhrLoadingStrategy extends LoadingStrategyBase {
/**
* Uses XHR's to download the code.
*/
public static class XhrDownloadStrategy implements DownloadStrategy {
@Override
public native void tryDownload(final RequestData request)/*-{
var xhr = new $wnd.XMLHttpRequest()
xhr.open("GET", request.@RequestData::getUrl()());
xhr.onreadystatechange = function() {
if (xhr.readyState == 4) {
// Clearing onreadystatechange otherwise it may cause memory leak (e.g. in IE8).
xhr.onreadystatechange = function() {}; // Clear callback
@XhrLoadingStrategy::onLoad(*)(request, xhr.status, xhr.statusText, xhr.responseText);
}
};
xhr.send(null);
}-*/;
}
/**
* Some UA's like Safari will have a "0" status code when loading from file:
* URLs. Additionally, the "0" status code is used sometimes if the server
* does not respond, e.g. if there is a connection refused.
*/
private static final int HTTP_STATUS_NON_HTTP = 0;
private static final int HTTP_STATUS_OK = 200;
@SuppressWarnings("unused") // Called via JSNI
private static void onLoad(RequestData request, int status, String statusText, String response) {
if ((status == HTTP_STATUS_OK || status == HTTP_STATUS_NON_HTTP)
&& response != null
&& response.length() != 0) {
request.tryInstall(response);
} else {
// If the download fails
request.onLoadError(new HttpDownloadFailure(request.getUrl(), status, statusText), true);
}
}
public XhrLoadingStrategy() {
super(new XhrDownloadStrategy());
}
}