com.sap.prd.mobile.ios.ota.webapp.BaseServlet.java Source code

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Here is the source code for com.sap.prd.mobile.ios.ota.webapp.BaseServlet.java

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/*
 * #%L
 * Over-the-air deployment webapp
 * %%
 * Copyright (C) 2014 SAP AG
 * %%
 * 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.
 * #L%
 */
package com.sap.prd.mobile.ios.ota.webapp;

import static java.lang.String.format;
import static org.apache.commons.lang.StringUtils.isEmpty;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.lang.StringUtils;

@SuppressWarnings("serial")
public abstract class BaseServlet extends HttpServlet {

    public static final String APPLICATION_BASE_URL_KEY = "applicationBaseUrl";

    @Override
    public String getInitParameter(String name) {
        return this.getServletContext().getInitParameter(name);
    }

    @Override
    public Enumeration<String> getInitParameterNames() {
        return this.getServletContext().getInitParameterNames();
    }

    /**
     * Returns an unmodifiable map containing all init parameters. 
     * @return
     */
    protected Map<String, String> getInitParameters() {
        HashMap<String, String> map = new HashMap<String, String>();
        try {
            Enumeration<String> initParameterNames = this.getServletContext().getInitParameterNames();
            while (initParameterNames.hasMoreElements()) {
                String name = initParameterNames.nextElement();
                map.put(name, this.getServletContext().getInitParameter(name));
            }
        } catch (IllegalStateException e) {
            if (!e.getMessage().equals("ServletConfig has not been initialized"))
                throw e;
        }
        return Collections.unmodifiableMap(map);
    }

    /**
     * Returns the configured Application Base URL or null if not configured via init parameters.<br/>
     * Use getApplicationBaseUrl(HttpServletRequest) to generate the URL based on a request.
     * @return the URL or null
     * @throws MalformedURLException
     */
    public URL getApplicationBaseUrl() throws MalformedURLException {
        String baseUrlString = getInitParameter(APPLICATION_BASE_URL_KEY);
        if (StringUtils.isBlank(baseUrlString))
            return null;
        return new URL(baseUrlString);
    }

    /**
     * Returns the Application Base URL based on the request.
     * @return the URL
     * @throws MalformedURLException
     */
    public URL getApplicationBaseUrl(HttpServletRequest request) throws MalformedURLException {
        String requestUrl = request.getRequestURL().toString(); //e.g. "http://host:8765/ota-service/HTML/UmVmZXJlcj1odHRw..."
        String contextPath = request.getContextPath().toString(); //e.g. "/ota-service" or "" if root context

        String result;
        if (!isEmpty(contextPath)) {
            int idx = requestUrl.indexOf(contextPath);
            if (idx < 0)
                throw new IllegalStateException(format("Cannot find '%s' in '%s'", contextPath, requestUrl));
            result = requestUrl.substring(0, idx + contextPath.length()); //e.g. "http://host:8765/ota-service"
        } else { //root context
            int idx = requestUrl.indexOf("//");
            idx = requestUrl.indexOf("/", idx + "//".length());
            result = requestUrl.substring(0, idx); //e.g. "http://host:8765"
        }
        return new URL(result);
    }

    /**
     * Returns the base URL of the service having the specified <code>servletName</code>.
     * 
     * @param request
     * @param servletName
     * @return base URL of the service
     * @throws MalformedURLException
     */
    public URL getServiceBaseUrl(HttpServletRequest request, String servletName) throws MalformedURLException {
        URL applicationBaseUrl = getApplicationBaseUrl(); //e.g. "http://host:8765/ota-service"
        if (applicationBaseUrl == null)
            applicationBaseUrl = getApplicationBaseUrl(request); //e.g. "http://host:8765/ota-service"
        String serviceUrlPattern = Utils.getServletMappingUrlPattern(request, servletName); //e.g. "/PLIST"
        return new URL(applicationBaseUrl.toExternalForm() + serviceUrlPattern);
    }

}