求教IEDA连接SQL时Tomcat报错的问题

[佩卡卡]

环境是IDEA+SQL
问题：以下代码chorme运行显示空白页,其余浏览器正常显示
代码如下：
index.jsp

<div id="shopmenuhot">
                  <h3 style="padding: 20px 0 10px 15px;font-size: 20px;">热销
                  <span style="font-size: 12px;color: #999;">大家喜欢吃，才叫真好吃。</span></h3>
                <%

                  request.setCharacterEncoding("UTF-8");
                  System.out.println(111);
                  List<Food> hotfoodList=(List<Food>)request.getAttribute("hotfoodList");
                  System.out.println(222);
                  if (hotfoodList == null)
                  {
                    System.out.println(333);
                    String path= request.getContextPath();
                    request.getRequestDispatcher(path+"IndexServlet").forward(request,response);
                  }
                  System.out.println(444);
                  for (int i = 0; i < hotfoodList.size(); i++) {
                    Food hotfood = hotfoodList.get(i);
                %>
                <div class="menufood">
                  <span class="col-1"><img class="menufoodimg" src="<%=hotfood.getImage()%>"></span>
                  <div class="col-2">
                    <h3 class="menufoodname"><%=hotfood.getFoodname()%></h3>
                    <span class="evaluation icon-star">(4.5)</span>
                    <span><%=hotfood.getIntroduct()%></span>
                  </div>
                  <span class="col-3 menufoodprice">¥<%=hotfood.getPrice()%></span>
                  <span class="col-4"><button class="menubutton">加入购物车</button></span>
                </div>

                <%  }
                %>
            </div>

IndexServlet.java:

public class IndexServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");

        String foodname=request.getParameter("foodname");
        String price=request.getParameter("price");
        String inventory=request.getParameter("inventory");
        String type=request.getParameter("type");
        String image=request.getParameter("image");
        String introduct =request.getParameter("introduct");

        Food food=new Food();
        FoodDao foodDao=new FoodDao();

        List<Food> hotfoodList=foodDao.getHotFood();
        request.setAttribute("hotfoodList",hotfoodList);


        request.getRequestDispatcher("index.jsp").forward(request, response);
    }
}

为什么控制打印出来是
111
222
333
111
222
444
444
这里的444为什么出现2个不是很明白

报错代码是Tomcat Localhost Log里的

07-Jun-2018 22:41:45.688 严重 [http-nio-8080-exec-5] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [jsp] in context with path [] threw exception [An exception occurred processing [/index.jsp] at line [153]

150:                     request.getRequestDispatcher(path+"IndexServlet").forward(request,response);
151:                   }
152:                   System.out.println(444);
153:                   for (int i = 0; i < hotfoodList.size(); i++) {
154:                     Food hotfood = hotfoodList.get(i);
155:                 %>
156:                 <div class="menufood">


Stacktrace:] with root cause
 java.lang.NullPointerException
	at org.apache.jsp.index_jsp._jspService(index_jsp.java:282)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:444)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:494)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:407)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:754)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1376)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:844)

学习java web 1个月,学校课程
第一次提问 看不清楚的地方麻烦说一声 谢谢！！

[xiao潇]

对的，还是会执行的，你要加 return 才会终止执行。

[weixin_42418973]

不太会～～～～～～～～～～～～～～～～～～

[QWERT4745]

Food hotfood = hotfoodList.get(i); 看下hotfood是否取到值

[xiao潇]

111 222 (333 请求发送到了doGet, doGet 返回到index.jsp, 所以 index.jsp从头运行（111 222 444） ) 444 所以 打印的是 111 222 （333 （111 222 444 ） ） 444

[佩卡卡]

引用 1 楼 xiaobudian0381 的回复:

111 222 (333 请求发送到了doGet, doGet 返回到index.jsp, 所以 index.jsp从头运行（111 222 444） ) 444 所以 打印的是 111 222 （333 （111 222 444 ） ） 444

意思是if里面执行完444还是继续执行的吗，那下面那些内容呢？我以为进到if里面下面的都不会执行了。

[佩卡卡]

引用 2 楼 QWERT4745 的回复:

Food hotfood = hotfoodList.get(i); 看下hotfood是否取到值

可以正常取到值,早上又试了一下发现是

 String path= request.getContextPath();
                    request.getRequestDispatcher(path+"IndexServlet").forward(request,response);

这段话的问题,从其他页面进入IndexServlet.java再跳转到Index.jsp页面可以正常显示，但是不明白为什么