会话属性在筛选器中为空

Question

public class ServletResponseMocker implements Filter {

    private ServletContext context;
    private ConcurrentHashMap<String,String> hmURI_FileNameMap=new ConcurrentHashMap<String, String>();
    private ConcurrentHashMap<String,List<String>> hmURI_SessionAttrLMap=new ConcurrentHashMap<String, List<String>>();

    private String rootPath;

    public void init(FilterConfig fConfig) throws ServletException {
        this.context = fConfig.getServletContext();         
        rootPath=System.getProperty("WAR_ROOT_PATH");
    }

    public void doFilter(ServletRequest request, ServletResponse response,
        FilterChain chain) throws IOException, ServletException {

    HttpServletRequest req = (HttpServletRequest) request;
    HttpServletResponse res = (HttpServletResponse) response;

    String uri = req.getRequestURI();
    boolean bToBeProcessed = false;

    if (uri.startsWith("some/pattern"))
        bToBeProcessed = true;

    if (bToBeProcessed) {

        res.setCharacterEncoding(System.getProperty("CHARSETTYPE"));
        OutputStream out = res.getOutputStream();
        byte responseContent[] = null;
        String filename = null;
        if (hmURI_FileNameMap.containsKey(uri)) {
            filename = hmURI_FileNameMap.get(uri);

            responseContent = Utils.readBytesFromFile(rootPath + "\\somefolder\\"
                    + filename);
            res.setContentType("text/html;charset=UTF-8");
            res.setContentLength(responseContent.length);
            HttpSession session = req.getSession(false);
            if (session != null) {

                if (hmURI_SessionAttrLMap.get(uri) != null)
                    session.setAttribute("ClientXSL",
                            hmURI_SessionAttrLMap.get(uri));

            }

            res.setHeader("X-FRAME-OPTIONS", "SAMEORIGIN");
        } else {

            filename = uri.substring(uri.lastIndexOf("/") + 1) + ".vdb";
            hmURI_FileNameMap.put(uri, filename);

            ResponseWrapper wrapper = new ResponseWrapper(res);

            chain.doFilter(request, wrapper);
            HttpSession session = req.getSession(false);
            // This session attribute is set by some filter in chain and is
            // always not null here.
            List<String> clientXSLList = (List) session
                    .getAttribute("ClientXSL");
            if (clientXSLList != null) {

                hmURI_SessionAttrLMap.put(uri, clientXSLList);
            }

            responseContent = wrapper.getData();
            /*Writing data to text file*/

        }
        out.write(responseContent);
        out.flush();
        out.close();
    } else {

        // To identify the 2nd servlet of the screen which is same for all
        // screens
        if(uri.startsWith("/someother/pattern/com.second.servlet.fetchXSL")){

        HttpSession session = req.getSession(false);
        if (session != null) {
            // Below session attributes always comes as not null during
            // fisrst time screen loading. However, comes as null when
            // static response is sent for subsequent servlet hit.
            List<String> clientXSLList = (List) session
                    .getAttribute("ClientXSL");
            if (clientXSLList != null)
                this.context.log("Getting clientXSL list from session:"
                        + Arrays.toString(clientXSLList.toArray()));
        }
    }
    chain.doFilter(request, response);
}

    public void destroy() {
    }


}

Answer 1

Ok发现了问题。

对于ques1:我忽略了第二个servlet中的代码。每当它被击中时，它就清除会话属性。因此，当我捕获第二次命中的第一个servlet的http响应时，会话属性已经为NULL。因此，它们在第二个servlet中是空的。

对于ques2:问题是我在过滤器中的代码。

List<String> clientXSLList = (List) session
                    .getAttribute("ClientXSL");
            if (clientXSLList != null) {

                hmURI_SessionAttrLMap.put(uri, clientXSLList);
            }

ArrayList<String> clientXSLList = (ArrayList<String>) session
                    .getAttribute("ClientXSL");
            if (clientXSLList != null) {

                hmURI_SessionAttrLMap.put(uri, clientXSLList.clone());
            }