package com.mozilla.bespin;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import javax.servlet.ServletContext;import javax.servlet.ServletConfig;import java.util.ArrayList;import java.util.Collections;import java.util.List;/** * Bag for state managed by {@link BaseServlet}. Used in place of a {@link java.util.Map} to obviate need to cast for * common state types. */public class RequestContext {    private HttpServletRequest req;    private HttpServletResponse resp;    private HttpServlet servlet;    private List<String> parameters = new ArrayList<String>();    public RequestContext(HttpServlet servlet, HttpServletRequest req, HttpServletResponse resp) {        this.servlet = servlet;        this.req = req;        this.resp = resp;    }    public RequestContext(HttpServlet servlet, HttpServletRequest req, HttpServletResponse resp, List<String> parameters) {        this.servlet = servlet;        this.req = req;        this.resp = resp;        this.parameters.addAll(parameters);    }    public HttpServlet getServlet() {        return servlet;    }    public HttpServletRequest getReq() {        return req;    }    public HttpServletResponse getResp() {        return resp;    }    // -- Convenience    public ServletContext getServletContext() {        return servlet.getServletContext();    }    public ServletConfig getServletConfig() {        return servlet.getServletConfig();    }    public HttpSession getSession() {        return req.getSession();    }    /**     * Guards against index out of bounds exceptions; returns null if the index is out of bounds     *     * @param index     * @return     */    public String parameter(int index) {        return (parameters.size() > index) ? parameters.get(index) : null;    }    /**     * Returns an unmodifiable wrapper around the parameter list     *      * @return     */    public List<String> getParameterList() {        return Collections.unmodifiableList(parameters);    }    /**     * Pops the first item off the parameter list     *     * @return     */    public String popParam() {        return (parameters.isEmpty()) ? null : parameters.remove(0);    }}