在不断重复这些行之后,Tomcat给了我StackOverflowError,这DiceBoardDispatcher是我的HttpServlet 所在的地方,在第34行中,我正在调用requestDispatcher#forward()。
DiceBoardDispatcher
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>
我想做的是在同一页面上同时执行2个操作。我以为我会这样设置。每个动作都要经过自己的动作,Filter并且都以Servlet分派到的结尾JSP。
Filter
Servlet
JSP
我的网址格式映射曾经是to /diceBoard/*,它是网络应用中某个文件夹。从那里改变到/dices/*解决问题url/dices。现在,我可以正常访问该页面了,但是当url/dices/roll我进入无限循环时(无论是POST还是GET)。
/diceBoard/*
/dices/*
url/dices
url/dices/roll
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() { } }
这是您的错误所在的行:
RequestDispatcher view = request.getRequestDispatcher("diceBoardPage.jsp");
根据getRequestDispatcher API,输入uri是 相 对于当前servlet上下文的,因此,当您在以下位置执行servlet时
/dices/roll
…并执行“ diceBoardPage.jsp”的调度,实际上是调度到
/dices/diceBoardPage.jsp
将该模式映射到哪个servlet?根据您的部署描述符,每个以“ / dices / *”开头的URL都映射到DiceBoard。IE相同的servlet。这是导致您的StackOverflowError的无限循环。
DiceBoard
如果JSP必须保留在dicesuri内,则必须限制映射DiceBoardservlet 的URL模式。如果需要,请不要犹豫添加几个值:
dices
<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>