Question

我正在尝试使用生成的HTML代码编写servlet，而不是打印出静态HTML。

我正在使用Eclipse-EE Europa和Tomcat 6.

我尝试使用HERE

中的流动提示

但不是打印所需的属性似乎忽略属性或属性的jsp是空的。

这是servlet：

package com.serv.pac;


import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;

/**
 * Servlet implementation class for Servlet: testServlet
 *
 */
 public class testServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
   static final long serialVersionUID = 1L;

    /* (non-Java-doc)
     * @see javax.servlet.http.HttpServlet#HttpServlet()
     */
    public testServlet() {
        super();
    }       

    /* (non-Java-doc)
     * @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String message = "doGet response";

        request.setAttribute("message", message);
        request.getRequestDispatcher("/testServlet/WEB-INF/index1.jsp").forward(request, response);
        PrintWriter out = response.getWriter();
        out.println("the servlet");
    }   

    /* (non-Java-doc)
     * @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        System.out.println("first servlet");
    }               
}

这是JSP

<!doctype html>
<html lang="en">
    <head>
        <title>SO question 2370960</title>
    </head>
    <body>
         <p>Message: ${message}</p>
    </body>
</html>

以下是：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>servlet1_test</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>

    <welcome-file>index1.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>testServlet</display-name>
    <servlet-name>testServlet</servlet-name>
    <servlet-class>com.serv.pac.testServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>testServlet</servlet-name>
    <url-pattern>/testServlet</url-pattern>
  </servlet-mapping>
</web-app>

这就是我在浏览器中获得的内容：

<!doctype html>
<html lang="en">
    <head>
        <title>SO question 2370960</title>
    </head>
    <body>
         <p>Message: </p>
    </body>
</html>

正如人们可能会看到html正文中的“消息”之后没有任何内容，就好像消息属性为空。

谢谢

Answer 1

我发现这种情况的唯一方法是您实际上并未访问Servlet。

您已宣布<welcome-file>

<welcome-file>index1.jsp</welcome-file>

所以，如果你试图点击

localhost:8080/YourContextPath

默认Servlet将呈现并向您发送缺少message属性的jsp。

如果您想点击实际Servlet，则需要使用

localhost:8080/YourContextPath/testServlet

请注意，您需要更改

request.getRequestDispatcher("/testServlet/WEB-INF/index1.jsp").forward(request, response);

到

request.getRequestDispatcher("/WEB-INF/index1.jsp").forward(request, response);

和将您的文件移至WEB-INF。

Java Servlet JSP不打印属性

1 个答案: