Question

我的HttpServlet片段：

   protected void doGet(HttpServletRequest httpServletRequest,
                         HttpServletResponse httpServletResponse) throws ServletException,
                                                                         IOException {
        final String[] values = httpServletRequest.getParameterValues("p");
        final int p;
        if (values != null && values.length > 0) {
            p = Integer.parseInt(values[0]);
        } else {
            p = 0;
        }
        final ServletContext context = super.getServletContext();
        switch (p) {
        case 0:
            {

                final CityRepresentationBean bean =
                    new CityRepresentationBean(ds);
                final RequestDispatcher rqDsp;
                try {
                    rqDsp =
                            context.getRequestDispatcher(bean.act(httpServletRequest));
                    rqDsp.forward(httpServletRequest, httpServletResponse);
                } catch (ConnectionException e) {
                    throw new ServletException(e);
                }
 ......
}

主要问题是我得到了StackOverFlow Exception。从Debug我发现我得到了ConnectionException，然后在throw new ServletException(e)之后再次调用doGet方法（我甚至没有一个可以调用它的线索）。

问题是如果浏览器只调用一次URL，如何多次调用servlet？

java.lang.StackOverflowError
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:303)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:183)
    at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:523)
    at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:253)
    at project2.FrontController.doGet(FrontController.java:64)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:183)
    at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:523)
    at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:253)
    at project2.FrontController.doGet(FrontController.java:64)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:183)
    at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:523)
    at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:253)
    at project2.FrontController.doGet(FrontController.java:64)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:183)
    at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:523)
    at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:253)
    at project2.FrontController.doGet(FrontController.java:64)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:183)
    at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:523)
    at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:253)
    at project2.FrontController.doGet(FrontController.java:64)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)

Answer 1

该servlet的网址格式也与bean.act(httpServletRequest)中RequestDispatcher#forward()返回的网址相匹配。

所以，你有两个选择：

将servlet映射到更具体的URL模式。 /*或其他地方至少不。例如，/pages/*或*.do。
确保act()返回的网址与servlet的网址格式不匹配。

重复doGet电话

1 个答案:

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