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java - servlet 和 JSP 的使用

转载 作者：行者123 更新时间：2023-11-29 20:42:17 25 4
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我已经创建了一个小应用程序，但在 Tomcat 服务器 7 中运行一段代码时遇到问题。我想创建一个简单的登录页面。我用MySQL建立了一个数据库。我的表单在浏览器中正确显示，但当我按下提交按钮时，出现 404 错误。我用过servlet和jsp。如果有人看一下我下面的代码，我将不胜感激。

LoginKlientiServlet.java:

    package prorent.controllers;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.sql.DriverManager;
  import java.sql.ResultSet;
  import java.sql.SQLException;

 import javax.servlet.RequestDispatcher;
 import javax.servlet.ServletException;
 import javax.servlet.annotation.WebServlet;
//import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.PreparedStatement;
import java.io.*;
import javax.servlet.http.*;
import javax.servlet.*;
import java.sql.*;


import prorent.DAO.LoginKlientiDAO;
//@(name="LoginKlientiServlet", urlPatterns= {"/LoginKlientiServlet"})
public class LoginKlientiServlet extends HttpServlet{

private static final long serialVersionUID = 1L;

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    String user = request.getParameter("username");
    String pass = request.getParameter("password");
    String repass = request.getParameter("repassword");
    try {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/pro", "root", "erida");
        PreparedStatement pst = (PreparedStatement) conn.prepareStatement("Select username,password, repassword from klienti where username=? and password=? and repassword=?");
        pst.setString(1, user);
        pst.setString(2, pass);
        pst.setString(2, repass);
        ResultSet rs = pst.executeQuery();
        if (rs.next()) {
            out.println("Correct login credentials");
        } 
        else {
            out.println("Incorrect login credentials");
        }
    } 
    catch (ClassNotFoundException | SQLException e) {
        e.printStackTrace();
    }
}
}

登录KlientiDAO.java

    <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<html>
   <head>
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 <title>Login Application</title>
 </head>
  <body>
   <form action="LoginKlientiServlet" method="post">
    <fieldset style="width: 300px">
        <legend> Login to App </legend>
        <table>
            <tr>
                <td>User ID</td>
                <td><input type="text" name="username" required="required" /></td>
            </tr>
            <tr>
                <td>Password</td>
                <td><input type="password" name="password" required="required" /></td>
            </tr>
            <tr>
                <td>Repassword</td>
                <td><input type="password" name="repassword" required="required" /></td>
            </tr>
            <tr>
                <td><input type="submit" value="Login" /></td>
            </tr>
        </table>
    </fieldset>
</form>

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"     xmlns:jsp="http://java.sun.com/xml/ns/javaee/jsp"
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"
metadata-complete="true" version="2.5">

<display-name>Jap me qera</display-name>


<servlet>

    <description />

    <display-name>LoginKlientiController</display-name>

    <servlet-name>LoginKlienti-DAO</servlet-name>

    <servlet-class>prorent.controllers.LoginKlientiServlet</servlet-class>

</servlet>



    <servlet-mapping>

    <servlet-name>login-lista</servlet-name>

    <url-pattern>/listalog</url-pattern>



</servlet-mapping>

我的控制台显示此错误消息

      Jul 25, 2016 2:48:40 PM org.apache.catalina.core.AprLifecycleListener init
  INFO: The APR based Apache Tomcat Native library which allows optimal      performance in production environments was not found on the java.library.path: C:\Program Files\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:/Program Files/bin/server;C:/Program Files/bin;C:/Program Files/lib/amd64;C:\Program Files\WinRAR;C:\ProgramData\Oracle\Java\javapath;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\QuickTime\QTSystem\;C:\Program Files (x86)\Skype\Phone\;C:\Users\USER\AppData\Local\Temp\Rar$EX59.800\eclipse;;.
  Jul 25, 2016 2:48:40 PM org.apache.tomcat.util.digester.SetPropertiesRule begin
 WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:prorent' did not find a matching property.
Jul 25, 2016 2:48:40 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-bio-8080"]
Jul 25, 2016 2:48:40 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
Jul 25, 2016 2:48:40 PM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 899 ms
Jul 25, 2016 2:48:40 PM org.apache.catalina.core.StandardService startInternal
INFO: Starting service Catalina
Jul 25, 2016 2:48:40 PM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/7.0.47
Jul 25, 2016 2:48:41 PM org.apache.catalina.util.SessionIdGenerator createSecureRandom
INFO: Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took [197] milliseconds.
Jul 25, 2016 2:48:41 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-bio-8080"]
Jul 25, 2016 2:48:41 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
Jul 25, 2016 2:48:41 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 1164 ms

提前谢谢您!

最佳答案

您的表单将数据提交到 URL /LoginKlientiServlet，但您没有该 URL 模式的任何 Servlet 映射。

也许您可以在 web.xml 中添加 URL 模式，就像您有 /listalog 一样。例如，

<servlet-mapping>
    <servlet-name>LoginKlienti-DAO</servlet-name>
    <url-pattern>/LoginKlientiServlet</url-pattern>
</servlet-mapping>

关于java - servlet 和 JSP 的使用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38570299/

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