Question

Tomcat在不断重复这些行之后给了我StackOverflowError，其中DiceBoardDispatcher是我的HttpServlet，而在第34行我正在调用requestDispatcher#forward()。

nl.rickhurkens.rollDice.web.diceBoard.DiceBoardDispatcher.doGet(DiceBoardDispatcher.java:34)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        nl.rickhurkens.rollDice.web.diceBoard.DiceBoardDispatcher.doGet(DiceBoardDispatcher.java:34)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

我想这与我的部署有关，这是我的web.xml的相关部分：

  <servlet-mapping>
    <servlet-name>DiceBoard</servlet-name>
    <url-pattern>/dices/*</url-pattern>
  </servlet-mapping>

  <filter-mapping>
    <filter-name>RollDiceFilter</filter-name>
    <url-pattern>/dices/roll</url-pattern>
  </filter-mapping>
  <filter-mapping>
    <filter-name>SetSettingsFilter</filter-name>
    <url-pattern>/dices/setup</url-pattern>
  </filter-mapping>

我要做的是让两个动作都登陆同一页面。我以为我会这样设置它。每个操作都会通过自己的Filter进行操作，它们都会在Servlet中以JSP的形式结束。

我的url-patter映射曾经是/diceBoard/*，这是web-app中的某个文件夹。从那里更改为/dices/*在转到url/dices时解决了问题。现在我可以正常访问该页面，但是当转到url/dices/roll时，我得到了无限循环（无论是POST还是GET）。

编辑：我的servlet代码：

public class DiceBoardDispatcher extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        RequestDispatcher view = request.getRequestDispatcher("diceBoardPage.jsp");
        view.forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        RequestDispatcher view = request.getRequestDispatcher("diceBoardPage.jsp");
        view.forward(request, response);
    }
}

和RollDiceFilter：

public class RollDiceFilter implements Filter {
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest)request;
        HttpServletResponse res = (HttpServletResponse)response;
        HttpSession session = req.getSession();

        DiceBoard diceBoard = (DiceBoard)session.getAttribute("diceBoard");
        String[] lockedValues = req.getParameterValues("lock");

        diceBoard.unlockAllDice();
        if (lockedValues != null) {
            for (String value : lockedValues) {
                if (value != null) {
                    try {
                        diceBoard.lockDice(Integer.parseInt(value));
                    } catch (DiceNotInCollectionException e) {
                        // TODO: redirect to error page.
                        e.printStackTrace();
                    }
                }
            }
        }
        diceBoard.getCup().roll();

        chain.doFilter(req, res);
    }

    public void init(FilterConfig fConfig) throws ServletException { }
    public void destroy() { }
}

Answer 1

这是您的错误所在的行：

RequestDispatcher view = request.getRequestDispatcher("diceBoardPage.jsp");

根据getRequestDispatcher API，输入uri是 relative 到当前的servlet上下文，所以当你在

执行你的servlet时

/dices/roll

...它执行“diceBoardPage.jsp”调度，它实际上是调度到

/dices/diceBoardPage.jsp

什么servlet将此模式映射到？根据您的部署描述符，以“/ dices / *”开头的每个URL都映射到DiceBoard。 I.E.同一个servlet。这是导致StackOverflowError的无限循环。

如果JSP必须保留在dices uri中，则必须限制映射DiceBoard servlet的URL模式。如果需要，请不要犹豫，添加几个值：

<servlet-mapping>
    <servlet-name>DiceBoard</servlet-name>
    <url-pattern>/dices/one</url-pattern>
    <url-pattern>/dices/two</url-pattern>
    <url-pattern>/dices/three</url-pattern>
</servlet-mapping>

请求Tomis上的Tomcat infinte循环#dward（）。的StackOverflowError

1 个答案: