com.google.speedtracer.client.util.Xhr.java Source code

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Here is the source code for com.google.speedtracer.client.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 com.google.speedtracer.client.util;

import com.google.gwt.xhr.client.ReadyStateChangeHandler;
import com.google.gwt.xhr.client.XMLHttpRequest;
import com.google.speedtracer.client.util.dom.WindowExt;

/**
 * Simple utility class for using {@link XMLHttpRequest}.
 */
public class Xhr {
    /**
     * Interface for getting notified when an XHR successfully completes, or
     * errors out.
     */
    public interface XhrCallback {
        void onFail(XMLHttpRequest xhr);

        void onSuccess(XMLHttpRequest xhr);
    }

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

        private Handler(XhrCallback 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();
            }
        }
    }

    public static void get(String url, XhrCallback callback) {
        request(create(), "GET", url, callback);
    }

    public static void get(WindowExt window, String url, XhrCallback callback) {
        request(create(window), "GET", url, callback);
    }

    public static void head(String url, XhrCallback callback) {
        request(create(), "HEAD", url, callback);
    }

    public static void head(WindowExt window, String url, XhrCallback callback) {
        request(create(window), "HEAD", url, callback);
    }

    public static void post(String url, String requestData, String contentType, XhrCallback callback) {
        request(create(), "POST", url, requestData, contentType, callback);
    }

    public static void post(WindowExt window, String url, String requestData, String contentType,
            XhrCallback callback) {
        request(create(window), "POST", url, requestData, contentType, callback);
    }

    /**
     * Replacement for XMHttpRequest.create() to allow using this method in a
     * Chrome Extensions background page.
     */
    private static native XMLHttpRequest create() /*-{
                                                  return new XMLHttpRequest();
                                                  }-*/;

    private static native XMLHttpRequest create(WindowExt window) /*-{
                                                                  return new window.XMLHttpRequest();
                                                                  }-*/;

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

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