从JSP调用servlet [英] Calling servlet from JSP

问题描述

基本上，我想在JSP页面上的ArrayList中显示产品.我已经在servlet代码中做到了.但是没有输出.

Basically, I want to display the products in an ArrayList on a JSP page. I have done that in the servlet code. But theres no output.

我还必须将products.jsp放在/WEB-INF文件夹中吗?当我这样做时，会收到请求的非资源错误.

Also Do I have to place products.jsp in the /WEB-INF folder? When I do that, I get a requested not resource error.

我的Servlet代码(InventoryServlet.java)

My Servlet Code (InventoryServlet.java)

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    try {
        List<Product> products = new ArrayList<Product>();
        products = Inventory.populateProducts(); // Obtain all products.
        request.setAttribute("products", products); // Store products in request scope.
        request.getRequestDispatcher("/products.jsp").forward(request, response); // Forward to JSP page to display them in a HTML table.
    } catch (Exception ex) {
        throw new ServletException("Retrieving products failed!", ex);
    }

}

我的JSP页面(products.jsp)

My JSP Page (products.jsp)

<h2>List of Products</h2>

<table>
    <c:forEach items="${products}" var="product">
       <tr>
           <td>${product.Description}</td>
          <td>${product.UnitPrice}</td>
       </tr>
    </c:forEach>
</table>

Web.xml

<web-app version="3.0"
        xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> 

 <servlet>
   <servlet-name>Inventory</servlet-name>
   <servlet-class>com.ShoppingCart.InventoryServlet</servlet-class>
 </servlet>
 <servlet-mapping>
    <servlet-name>Inventory</servlet-name>
    <url-pattern>/products</url-pattern>
  </servlet-mapping>
</web-app>

推荐答案

您需要通过请求servlet URL而不是JSP URL来打开页面.这将调用doGet()方法.

You need to open the page by requesting the servlet URL instead of the JSP URL. This will call the doGet() method.

在/WEB-INF中放置JSP可以有效地防止最终用户直接打开它，而无需使用servlet的doGet()方法.即/WEB-INF中的文件不可公共访问.因此，如果必须对Servlet进行预处理，则需要这样做.将JSP放在/WEB-INF文件夹中，然后将requestdispatcher更改为指向它.

Placing JSP in /WEB-INF effectively prevents the enduser from directly opening it without involvement of the doGet() method of the servlet. Files in /WEB-INF are namely not public accessible. So if the preprocessing of the servlet is mandatory, then you need to do so. Put the JSP in /WEB-INF folder and change the requestdispatcher to point to it.

request.getRequestDispatcher("/WEB-INF/products.jsp").forward(request, response);

但是您需要更改所有现有链接以指向servlet URL而不是JSP URL.

But you need to change all existing links to point to the servlet URL instead of the JSP URL.

• "Servlet信息"页面

这篇关于从JSP调用servlet的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！