java.lang.NumberFormatException: For input string: "orderItems"报错解决记录

前言
orderItems一个javaBean中内置对象。
以下是报错信息：

java.lang.NumberFormatException: For input string: "orderItems"
    at java.lang.NumberFormatException.forInputString(Unknown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at javax.el.ListELResolver.coerce(ListELResolver.java:157)
    at javax.el.ListELResolver.getValue(ListELResolver.java:70)
    at org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:110)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:169)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
    at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:943)
    at org.apache.jsp.order_005flist_jsp._jspx_meth_c_005fforEach_005f1(order_005flist_jsp.java:285)
    at org.apache.jsp.order_005flist_jsp._jspx_meth_c_005fforEach_005f0(order_005flist_jsp.java:249)
    at org.apache.jsp.order_005flist_jsp._jspService(order_005flist_jsp.java:161)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:720)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:466)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:391)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:318)
    at cn.mldn.web.servlet.ProductServlet.myOrder(ProductServlet.java:130)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at cn.mldn.web.servlet.BeanServlet.service(BeanServlet.java:35)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

java类

    private String oid;
    private Date ordertime;
    private double total;
    private int state;//支付状态，1，已支付，2未支付

    private String address;
    private String name;
    private String telephone;
    private User user;

    List orderItems=new ArrayList();

此报错字面意思为数字格式报错。
1，先检查一下对应的属性类型，是否与封装的数据类型对应。
2，若1，已排除，可参考我的问题所在
此为封装数据代码：

    protected void myOrder(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //1,判断是否用户登录
        HttpSession session = request.getSession();
        User user = (User) session.getAttribute("user");
        if(user==null)
        {
            //若未空，则需登陆
            response.sendRedirect(request.getContextPath()+"/login.jsp");
            return;
        }

        //2.检索出来所有的订单Orders by uid
        String uid=user.getUid();
        ServiceServlet service=new ServiceServlet();
        List<Order> ordersList=null;
        try {
            ordersList= service.findOrdersByUid(uid);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        //3.检索出来所有的订单项，商品项通过 pid相等。然后oid以订单项为主
        if(ordersList!=null)
        {
        for (Order order : ordersList) {
            String  oid = order.getOid();   

            try {
                List<Map<String, Object>>  listMap = service.findOderItemByOid(oid);
                for(Map<String, Object> map:listMap)
                {

                    try {
                        //从map中取出count subtotal 封装到OrderItem中
                        OrderItem item = new OrderItem();
                        //item.setCount(Integer.parseInt(map.get("count").toString()));
                        BeanUtils.populate(item, map);
                        //从map中取出pimage pname shop_price 封装到Product中
                        Product product = new Product();
                        BeanUtils.populate(product, map);
                        //将product封装到OrderItem
                        item.setProduct(product);
                        //将orderitem封装到order中的orderItemList中
                        order.getOrderItems().add(item);
                    } catch (IllegalAccessException | InvocationTargetException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }

            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        }
        //将封装好的list集合传递到request域中。
        request.setAttribute("ordersList", ordersList);
        //跳转到订单信息页
        request.getRequestDispatcher("/order_list.jsp").forward(request, response);
    }

此为jsp中el代码

                <c:forEach items="${ordersList}" var="order">



                    <tbody>
                        <tr class="success">
                            <th colspan="5">订单编号:${order.oid}th>
                        tr>
                        <tr class="warning">
                            <th>图片th>
                            <th>商品th>
                            <th>价格th>
                            <th>数量th>
                            <th>小计th>
                        tr>
                        **********************************
                        <c:forEach items="${ordersList.orderItems}" var="orderItem">
                        **出错在此行代码，ordersList集合中无orderItems对象。***************
                        <tr class="active">
                            <td width="60" width="40%"><input type="hidden" name="id"
                                value="22"> <img src="${pageContext.request.contextPath }/${orderItem.product.pimage}" width="70"
                                height="60">td>
                            <td width="30%"><a target="_blank"> ${orderItem.product.pname }a>td>
                            <td width="20%">￥${orderItem.product.shop_price }td>
                            <td width="10%">${orderItem.count }td>
                            <td width="15%"><span class="subtotal">￥${orderItem.subtotal }span>td>
                        tr>

                        c:forEach>


                    tbody>

                    c:forEach>

解决：将jsp中的el代码进行检查，发现ordersList集合中并无orderItems对象，而是通过ordersList下的order中的orderItems。
所以代码改为：

forEach items="${order.orderItems}" var="orderItem">

总结：检查jsp中的el代码，是不是调用错了内置对象

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