nz.net.catalyst.mobile.dds.RequestInfo.java Source code

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Here is the source code for nz.net.catalyst.mobile.dds.RequestInfo.java

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/*
 * Copyright (C) 2010  Catalyst IT Limited
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package nz.net.catalyst.mobile.dds;

import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.collections.map.CaseInsensitiveMap;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A bean that holds important info about the http request
 * Create a new ReqeustInfo object and avoid modifying existing ones
 * This is not 100% immutable, its been made as immutable has possible
 * w/o over complicating it.
 * 
 * @author jun yamog
 *
 */
public class RequestInfo {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    public static final String REQUEST_INFO = "request-info";

    private Map<String, String> headers;

    public RequestInfo(Map<String, String> headers) {
        this.headers = Collections.unmodifiableMap(RequestInfo.getNewMap(headers));
        validateHeaders();
    }

    /**
     * creates a RequestInfo object based from the HttpServletRequest
     * 
     * use RequestInfo.getRequest when possible as it will cache the object
     * @param request
     */
    private RequestInfo(HttpServletRequest request) {
        HashMap<String, String> headers = new HashMap<String, String>();

        for (Enumeration<?> h = request.getHeaderNames(); h.hasMoreElements();) {
            String headerName = (String) h.nextElement();
            String headerValue = request.getHeader(headerName);

            logger.debug("header: " + headerName + " = " + headerValue);

            headers.put(headerName.toLowerCase(), headerValue);
        }

        this.headers = Collections.unmodifiableMap(getNewMap(headers));
        validateHeaders();
    }

    /**
     * this either creates a new RequestInfo or gets the cached instance from the
     * reqeust
     * @param request
     * @return
     */
    public static RequestInfo getRequestInfo(HttpServletRequest request) {
        RequestInfo requestInfo = (RequestInfo) request.getAttribute(REQUEST_INFO);
        if (requestInfo == null) {
            requestInfo = new RequestInfo(request);
            request.setAttribute(REQUEST_INFO, requestInfo);
        }

        return requestInfo;
    }

    @SuppressWarnings("unchecked") // CaseInsesitiveMap is not a generic class
    private static Map<String, String> getNewMap(Map<String, String> map) {
        return new CaseInsensitiveMap(map);
    }

    private void validateHeaders() throws IllegalArgumentException {
        if (!headers.containsKey("user-agent"))
            throw new IllegalArgumentException("required http header 'user-agent' is missing");
    }

    /**
     * convenience method get the user agent header which is the mostly used
     * header
     * @return
     */
    public String getUserAgent() {
        return StringUtils.defaultString(headers.get("user-agent"));
    }

    /**
     * get a new copy of the header map.
     * @return
     */
    public Map<String, String> getHeaders() {
        return getNewMap(headers);
    }

}