Question

我想使用servlet创建一个简单的网页。这是我考试的一个问题，我考试时考试成功，但是没有按照他们的预期进行，但现在我想澄清一下我的问题。我的问题是有一个网页，它分为两部分。在底部，它应显示文本框和文本区域以输入注释。还有一个提交按钮。当提交按钮点击时，输入的评论应显示在同一页面的顶部。为此，我创建了一个servlet调用Welcome.java，并使用iframe将其分为两部分。然后我创建了一个servlet调用test.java并在该servlet中创建了一个文本框和textarea。然后创建另一个servlet调用text22.java来捕获注释并显示它们。但它没有给出预期的产量我附上了这个页面现在看起来的截图，我想在页面顶部显示评论。请帮我解决这个问题。非常感谢你的帮助...

Welcome.java

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

    /**
     *
     * @author neil
     */

public class Welcome extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {


            out.println("<iframe src='test22' name='if1' width='100%' height='400px'>");
            out.println("</iframe>");
            out.println("<iframe src='test' name='if1' width='100%' height='200px'>");
            out.println("</iframe>");


        } finally {
            out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }


    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }


    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}

test.java

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

/**
 *
 * @author neil
 */
public class test extends HttpServlet {


    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {

            out.println("User Name" + "<input type='text' name='username'/>" + "<br>" + "<br>");
            out.println("<textarea name='comment' rows='25' cols='20'>" + "Write your comment");
            out.println("</textarea>");
            out.println("<input type='submit' value='Submit'/>");




        } finally {
            out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }


    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}

test22.java

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

/**
 *
 * @author neil
 */
public class A extends HttpServlet {


    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            ServletContext sc=request.getServletContext();
            String com= (String) sc.getAttribute("text");

            if(null==com){
              com = request.getParameter("comment"); 
            }else{
                com=com+"<br>"+request.getParameter("comment"); 
            }


            out.println(com);

            sc.setAttribute("comment", com);

        } finally {            
            out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }


    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }


    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}

Image

Answer 1

您不必使这个简单的servlet程序复杂化。您需要有一个jsp和servlet才能执行此操作。

您的要求是使用您首先提交数据并查看的相同页面。

首先使用textbox创建简单的jsp页面。您应该使用JSTL代替scriptlets，为了简单起见，我已经为您提供了scriptlet代码。

您的index.jsp看起来像这样，

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Submit and View Page</title>
</head>
<body>
     <!-- This part will enable only after submit your username -->
    <% 
      if(null != request.getParameter("username")){
         out.println("<fieldset><legend>Entered Name</legend>");
         out.println(request.getParameter("username"));
         out.println("</fieldset>");
      }
     %>
    <!-- End of view data -->
    <form action="HelloServlet">
        <label>User Name: </label><input type='text' name='username'/></br>
        <input type='submit' value='Submit'/>
    </form>
</body>
</html>

创建相应的servlet说HelloServlet，

package com;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HelloServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        // Receive the username
        String username = req.getParameter("username");

        // Set it into request object
        req.setAttribute("username", username);

        // Forward it into same index page
        req.getRequestDispatcher("index.jsp").forward(req, resp);
    }
}

配置部署描述符web.xml

<?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" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">

    <display-name>Sample_Servlet</display-name>

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

    <servlet>  
        <servlet-name>HelloServlet</servlet-name>  
        <servlet-class>com.HelloServlet</servlet-class>  
    </servlet>  

    <servlet-mapping>  
        <servlet-name>HelloServlet</servlet-name>  
        <url-pattern>/HelloServlet</url-pattern>  
    </servlet-mapping>  

</web-app>

确保您的文件夹结构如下所示，您也可以从教程中学习。

Answer 2

Ajax和Javascript可用于更新页面内容而无需刷新整个页面。

开发此应用程序的方法如下：

只需要一个网页，其中包含将页面分成两部分的代码。它应在第二部分显示文本框，文本区域和按钮。并在第一部分中显示div（以显示注释）。此页面还应包含单击按钮时要处理的代码。单击按钮时，应启动Ajax调用。这个ajax调用应该通过传递输入的注释来命中servlet。

servlet应该处理注释并将注释作为响应返回。通过编写javascript代码，可以将返回的注释添加到页面的第一部分。

使用servlet创建一个简单的Web页面

2 个答案: