com.google.web.bindery.requestfactory.gwt.client.DefaultRequestTransport.java Source code

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Here is the source code for com.google.web.bindery.requestfactory.gwt.client.DefaultRequestTransport.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.web.bindery.requestfactory.gwt.client;

import static com.google.gwt.user.client.rpc.RpcRequestBuilder.STRONG_NAME_HEADER;

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.Window.Location;
import com.google.web.bindery.requestfactory.shared.RequestFactory;
import com.google.web.bindery.requestfactory.shared.RequestTransport;
import com.google.web.bindery.requestfactory.shared.ServerFailure;

import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * An implementation of {@link RequestTransport} that uses a
 * {@link RequestBuilder}.
 */
public class DefaultRequestTransport implements RequestTransport {
    private static final String SERVER_ERROR = "Server Error";

    /**
     * The default URL for a DefaultRequestTransport is
     * <code>{@link GWT#getHostPageBaseURL()} + {@value #URL}</code> which may be
     * overridden by calling {@link #setRequestUrl(String)}.
     */
    public static final String URL = "gwtRequest";

    /*
     * A separate logger for wire activity, which does not get logged by the
     * remote log handler, so we avoid infinite loops. All log messages that could
     * happen every time a request is made from the server should be logged to
     * this logger.
     */
    private static final Logger wireLogger = Logger.getLogger("WireActivityLogger");

    private String requestUrl = GWT.getHostPageBaseURL() + URL;

    /**
     * Returns the current URL used by this transport.
     * 
     * @return the URL as a String
     * @see #setRequestUrl(String)
     */
    public String getRequestUrl() {
        return requestUrl;
    }

    public void send(String payload, TransportReceiver receiver) {
        RequestBuilder builder = createRequestBuilder();
        configureRequestBuilder(builder);

        builder.setRequestData(payload);
        builder.setCallback(createRequestCallback(receiver));

        try {
            wireLogger.finest("Sending fire request");
            builder.send();
        } catch (RequestException e) {
            wireLogger.log(Level.SEVERE, SERVER_ERROR + " (" + e.getMessage() + ")", e);
        }
    }

    /**
     * Override the default URL used by this transport.
     * 
     * @param url a String URL
     * @see #getRequestUrl()
     */
    public void setRequestUrl(String url) {
        this.requestUrl = url;
    }

    /**
     * Override to change the headers sent in the HTTP request.
     * 
     * @param builder a {@link RequestBuilder} instance
     */
    protected void configureRequestBuilder(RequestBuilder builder) {
        builder.setHeader("Content-Type", RequestFactory.JSON_CONTENT_TYPE_UTF8);
        builder.setHeader("pageurl", Location.getHref());
        builder.setHeader(STRONG_NAME_HEADER, GWT.getPermutationStrongName());
    }

    /**
     * Constructs a {@link RequestBuilder} using the {@link RequestBuilder#POST}
     * method sent to the URL returned from {@link #getRequestUrl()}.
     * 
     * @return a {@link RequestBuilder} instance
     */
    protected RequestBuilder createRequestBuilder() {
        return new RequestBuilder(RequestBuilder.POST, getRequestUrl());
    }

    /**
     * Creates a RequestCallback that maps the HTTP response onto the
     * {@link com.google.web.bindery.requestfactory.shared.RequestTransport.TransportReceiver
     * TransportReceiver} interface.
     * 
     * @param receiver a
     *          {@link com.google.web.bindery.requestfactory.shared.RequestTransport.TransportReceiver
     *          TransportReceiver}
     * @return a {@link RequestCallback} instance
     */
    protected RequestCallback createRequestCallback(final TransportReceiver receiver) {
        return new RequestCallback() {

            public void onError(Request request, Throwable exception) {
                wireLogger.log(Level.SEVERE, SERVER_ERROR, exception);
                receiver.onTransportFailure(new ServerFailure(exception.getMessage()));
            }

            public void onResponseReceived(Request request, Response response) {
                wireLogger.finest("Response received");
                if (Response.SC_OK == response.getStatusCode()) {
                    String text = response.getText();
                    receiver.onTransportSuccess(text);
                } else {
                    String message = SERVER_ERROR + " " + response.getStatusCode() + " " + response.getText();
                    wireLogger.severe(message);
                    receiver.onTransportFailure(new ServerFailure(message));
                }
            }
        };
    }
}