java - 错误500响应未提交

Question

我试图向我的 jsp 页面(即制造商详细信息)发送请求并通过 session 获取属性，但它抛出 500 错误。

    package com.osahub.disaster.controller;
    import java.io.IOException;

    import static com.osahub.disaster.controller.Ofymethodadmin.ofy;

    import java.io.PrintWriter;
    import java.util.Iterator;
    import java.util.List;

    import javax.servlet.ServletException;
    import javax.servlet.http.*;

       import com.osahub.disaster.controller.SendMail;

        @SuppressWarnings("serial")
         public class admin extends HttpServlet {
        public void doPost(HttpServletRequest req, HttpServletResponse resp)
                throws IOException, ServletException {
            resp.setContentType("text/plain");
            resp.getWriter().println("Data Saved!");

        PrintWriter out = resp.getWriter();

        String name= req.getParameter("name");
        String address = req.getParameter("address");
        String email = req.getParameter("email");
        String website = req.getParameter("website");
        String topex = req.getParameter("topex");
        String topdes = req.getParameter("topdes");
        String topmob = req.getParameter("topmob");
        String year = req.getParameter("year");
        String brand = req.getParameter("brand");
        String factory = req.getParameter("factory");
        String sector = req.getParameter("sector");
        String contactpername = req.getParameter("contactpername");
        String contactperdes = req.getParameter("contactperdes");
        String contactpermob = req.getParameter("contactpermob");

        HttpSession currentSession=req.getSession();
        currentSession.setAttribute("name", name);
        req.getRequestDispatcher("ManufacturerDetails.jsp").forward(req, resp);


        SendMail mail = new SendMail();
        mail.send(email, "send Test mail from gae" , "this is the mail body");



        ManufacturerDetails ad = new ManufacturerDetails(name,address,email,website,topex,topdes,topmob,year,brand,factory,sector,contactpername,contactperdes,contactpermob);
        ofy().save().entity(ad);
        ofy().clear();

        List<ManufacturerDetails> li = ofy().load().type(ManufacturerDetails.class).list();
        Iterator<ManufacturerDetails> iter = li.iterator();

        while(iter.hasNext())
        {
            ManufacturerDetails ad1 = iter.next();
            System.out.println(ad1.getName());
            System.out.println(ad1.getAddress());
            System.out.println(ad1.getEmail());
            System.out.println(ad1.getWebsite());
            System.out.println(ad1.getTopex());
            System.out.println(ad1.getTopdes());
            System.out.println(ad1.getTopmob());
            System.out.println(ad1.getYear());
            System.out.println(ad1.getBrand());
            System.out.println(ad1.getFactory());
            System.out.println(ad1.getSector());
            System.out.println(ad1.getContactpername());
            System.out.println(ad1.getContactpermob());
            System.out.println(ad1.getContactperdes());

        }
    resp.sendRedirect("about.jsp");


    }
    }

Answer 1

任何异常都可能导致 HTTP 状态代码 500 的响应。

但是，在您的情况下，似乎抛出了异常，因为您在 req.getRequestDispatcher("ManufacturerDetails.jsp") 之后调用 resp.sendRedirect("about.jsp"); .forward(req, resp);。

您不能这样做，因为一旦对 forward() 的调用完成，响应就会被提交。但是，这并不意味着 doPost() 方法返回控制权，它会继续执行。因此，resp.sendRedirect("about.jsp"); 会导致抛出 java.lang.IllegalStateException 异常，因为响应已经关闭。

你必须检查你的方法，并引入一个条件语句:

if (condition) {
    // do something
    req.getRequestDispatcher("ManufacturerDetails.jsp").forward(req, resp);
} else {
    // do something
    resp.sendRedirect("about.jsp");
}

另一种选择是在 req.getRequestDispatcher("ManufacturerDetails.jsp").forward(req, resp); 之后引入显式 return。