Question

我需要创建一个简单的应用程序，其中Servlet读取两个输入参数，检查数据库中是否有任何一个结果应该提示“失败”，否则“成功”。请更正此代码。非常感谢。

PromotionServlet.java

package promotion;

import java.io.*;

import java.util.*;

import java.sql.*;

import javax.servlet.*;
import javax.servlet.http.*;


public class PromotionServlet extends HttpServlet {
    public PromotionServlet() {
        super();
    }

    private ServletConfig config;
    String page = "PromotionResult.jsp";

    public void init(ServletConfig config) throws ServletException {
        this.config = config;
    }

    public void doGet(HttpServletRequest request,
                      HttpServletResponse response) throws ServletException,
                                                           IOException {
        PrintWriter out = response.getWriter();
        /*Establish connection to MySQL database*/

        String voucher_num = request.getParameter("voucher_num");
        String nic = request.getParameter("nic");


        String connectionURL =
            "jdbc:mysql://localhost:3306/customer_promotion";
        Connection connection = null;

        ResultSet rs;
        response.setContentType("text/html");
        //List dataList=new ArrayList();
        String id = "error";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(connectionURL, "root", "mobitel#123");
            Statement s = connection.createStatement();
            rs =s.executeQuery("Select * from promotion_tbl where voucher_num='" + voucher_num + "' OR  nic='" + nic + "'");
            String voucherNumber = "";
            String nicNumber = "";
            if (rs.next()) {
                rs.getString("voucher_num");
                rs.getString("nic");
                RequestDispatcher dispatcher = request.getRequestDispatcher(page);
            } else {
                s.executeUpdate("INSERT INTO promotion_tbl VALUES('" +
                                voucher_num + "','" + nic + "')");
                System.out.println("Data successfully entered to the database");
            }


        } catch (Exception e) {

            System.out.println("Exception is ;" + e);
            e.printStackTrace();

        }

        RequestDispatcher dispatcher = request.getRequestDispatcher(page);

        if (dispatcher != null) {

            dispatcher.forward(request, response);
        }

    }
}

的web.xml

<?xml version = '1.0' encoding = 'windows-1252'?>
<web-app 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_2_5.xsd"
         version="2.5" xmlns="http://java.sun.com/xml/ns/javaee">
  <servlet>
    <servlet-name>PromotionServlet</servlet-name>
    <servlet-class>promotion.PromotionServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>PromotionServlet</servlet-name>
    <url-pattern>/promotionservlet</url-pattern>
  </servlet-mapping>
</web-app>

PromotionJSP.jsp

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<%-- <%@ page contentType="text/html;charset=windows-1252"%>--%>
<!--<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=windows-1252"/>
    <title>PromotionJSP</title>
  </head>
  <body></body>
</html>-->

<%@ page contentType="text/html;charset=windows-1252"%>
<%@page language="java" import="java.util.*" %>
<html>


       <head>
       <title>Enter your Voucher Number and NIC number</title>
       </head>
      <body bgcolor="#999966">
              <p>&nbsp;</p>
              <form method="GET" action="PromotionServlet">

                     <p>
                            <font color="#800000" size="5">
                            <label for="Voucher_Number:">Enter Your Voucher Number </label></font>
                            <input type="text" name="voucher_num" size="20"></input>
                     </p>
                     <p>
                            <font color="#800000" size="5">
                            <label for="NIC_Number:">Enter your NIC Number :</label></font>
                            <input type="text" name="nic" size="20"></input>
                     </p>
                     <p>
                            <input type="submit" value="Submit"></input>

                     </p>

              </form>
       </body>

</html>

Answer 1

您似乎将结果打印到stdout流，而不是将其发送到结果页面。使用像

这样的东西

response.setAttribute("resultMessage","Data successfully entered to the database");

并在结果jsp上检索该响应属性并将其打印出来，如

c:out var="${resultMessage}"/>

（或直接在页面中使用变量）

字符串搜索有两个参数

1 个答案: