src/main/java/com/android/vts/api/BaseApiServlet.java

/*
 * Copyright (c) 2018 Google Inc. All Rights Reserved.
 *
 * 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.android.vts.api;

import com.google.apphosting.api.ApiProxy;
import java.util.Properties;
import java.util.logging.Logger;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletResponse;

/** An abstract class to be subclassed to create API Servlet */
public class BaseApiServlet extends HttpServlet {

    private static final Logger logger = Logger.getLogger(BaseApiServlet.class.getName());

    /** System Configuration Property class */
    protected Properties systemConfigProp = new Properties();

    /** Appengine server host name */
    protected String hostName;

    /**
     * This variable is for maximum number of entities per transaction You can find the detail here
     * (https://cloud.google.com/datastore/docs/concepts/limits)
     */
    protected int MAX_ENTITY_SIZE_PER_TRANSACTION = 300;

    @Override
    public void init(ServletConfig cfg) throws ServletException {
        super.init(cfg);

        systemConfigProp =
                Properties.class.cast(cfg.getServletContext().getAttribute("systemConfigProp"));

        this.MAX_ENTITY_SIZE_PER_TRANSACTION =
                Integer.parseInt(systemConfigProp.getProperty("datastore.maxEntitySize"));

        ApiProxy.Environment env = ApiProxy.getCurrentEnvironment();
        hostName =
                env.getAttributes()
                        .get("com.google.appengine.runtime.default_version_hostname")
                        .toString();
    }

    protected void setAccessControlHeaders(HttpServletResponse resp) {
        resp.setHeader("Access-Control-Allow-Origin", hostName);
        resp.setHeader("Access-Control-Allow-Methods", "GET, PUT, POST, OPTIONS, DELETE");
        resp.addHeader("Access-Control-Allow-Headers", "Content-Type");
        resp.addHeader("Access-Control-Max-Age", "86400");
    }
}