Servlet JSP Tutorial -- 1.10 Servlet JDBC Database Connection Example

末蓝、 2022-06-01 00:17 196阅读 0赞

`Servlet` `JDBC`数据库连接和`Log4j`集成是本教程的主题。我们已经提供了很多关于`java`中`servlet`的教程，本教程旨在使用所有这些信息来创建一个具有数据库连接和`log4j`集成功能的完整 Web 应用程序，以便进行日志记录。

如果您不熟悉这些内容，我强烈建议您查看以下教程。 它们都包含示例项目，您可以下载并运行该示例项目以了解`Servlet API`的核心概念。

1.  J2EE Web Application Overview
2.  Servlet Tutorial for Beginners
3.  Session Management in Servlets
4.  Servlet Filter
5.  Servlet Listener
6.  Servlet Exception Handling
7.  Servlet Cookie Example

--------------------

1.  Servlet JDBC Example  
    
    
    1.  Design Decisions
    2.  Servlet JDBC Example – Database Setup
    3.  Login and Registration HTML Pages
    4.  Deployment Descriptor and log4j configuration
    5.  Model Classes and Database Connection Manager Class
    6.  Servlet JDBC Example – Context Listener
    7.  Exception and Error Handler
    8.  Servlet Filter
    9.  Servlet Classes
    10. Home JSP Page
    11. Run the Servlet JDBC Example Application
    12. Download Resources

## Servlet JDBC Example ##

开发一个应该具有以下功能的 Web 应用程序。  
1. 用户可以注册登陆到应用程序；  
2. 用户信息应该保存在数据库中；  
3. 使用标准日志框架 `log4j`；  
4. 应用程序应该支持会话管理，没有会话那么 JSP 页面都不可见。用户可以随时从应用程序注销；  
5. 我们不应该在应用程序向用户展示应用程序或其他像 404 这样的常见错误和服务器细节。

一旦我们准备好了基本的应用程序，我们可以继续添加其他功能。

### Design Decisions ###

1.  因为登陆页面是应用程序的入口点，我们将有一个简单的用户可以输入它们的凭据：email 和密码的 `login.html` 页面。我们不能依靠 JavaScript 进行验证，所以我们将做服务器端验证和防备错误信息，我们将重定向用户到包含错误信息的登陆页面。
2.  我们会有一个 register.html 用来用户注册到我们的应用程序，我们将在登陆页面为新用户一共登陆页面的链接。用户应提供 email、密码、姓名和国家信息用于注册。  
    如果缺少任何信息，用户将保持在同一页面上，并显示错误消息。如果注册成功。用户将被转发到注册成功信息的登陆页面，用户可以通过电子邮件和密码进行登陆。
3.  我们将使用 `MySQL`数据库来保存用户信息。我们将为我们的应用程序创建一个新的数据库、用户和 Users 表。由于我们的应用程序完全依赖于数据库连接，我们将创建一个 `servlet context listener`来初始化数据库连接，并将其为其他 servlet设置为`context attribute`。  
    我们将通过部署描述文件来保持数据库配置细节的可配置型。我们还将添加 MySQL Java Connector jar 包到应用程序 libraries。
4.  由于我们要使用 `log4j` 在使用前正确配置，我们将利用 `servlet context listener` 来配置 `log4j`，并将 log4j 配置 XML 文件位置保存在 `web.xml` init parameters 中。我们将把我们的应用程序日志写在一个单独的日志文件 `dbexample.log` 中，以方便调试。
5.  如果出现“数据库连接错误”或 404 错误等异常，我们希望向用户展示一个有用的页面。我们将利用 servlet 异常处理并编写我们自己的 `Exception Handler` servlet，并在部署描述文件中配置
6.  一旦用户登陆成功，我们将为用户创建一个会话并将其转发到 home.js，在那里我们将显示用户的基本信息。我们将用一个模型类的用户将用户存储到会话中。用户主页还提供注销按钮，将使会话失效并将其转发到登陆页面。
7.  我们需要确保所有的 JSP 和其他资源只有在用户有效会话时才可以访问，为不是在所有的资源中保持会话验证登陆，我们将创建一个 Servlet 过滤器进行会话验证，并将其配置在部署描述文件中。
8.  我们将使用 Servlet 3.0 特性用于 servlet 配置，监听器、过滤器代替将所有这些特性保存在部署描述文件中。我们将使用 IDEA 进行开发，并使用 Tomcat 8 进行部署。

基于上述需求和设计决策，我们将创建我们的动态 web 项目，其目录结构将如下图所示。  
![这里写图片描述][SouthEast]

让我们来了解每个组件并理解它们的实现。

### Servlet JDBC Example – Database Setup ###

我们将使用下面的 `SQL` 脚本来为我们的应用程序创建新的数据库，用户和表设置。

-- login with root to create user, DB and table and provide grants
    
    create user 'pankaj'@'localhost' identified by 'pankaj123';
    
    grant all on *.* to 'pankaj'@'localhost' identified by 'pankaj123';
    
    create database UserDB;
    
    use UserDB;
    
    CREATE TABLE `Users` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(20) NOT NULL DEFAULT '', `email` varchar(20) NOT NULL DEFAULT '', `country` varchar(20) DEFAULT 'USA', `password` varchar(20) NOT NULL DEFAULT '', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

### Login and Registration HTML Pages ###

登陆和注册 HTML 页面时用表单提交用户信息的简单页面。它们的代码如下：

`login.html`

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Login Page</title>
    </head>
    <body>
    <h3>Login with email and password</h3>
    <form action="Login" method="post">
        <strong>User Email</strong>:<input type="text" name="email"><br>
        <strong>Password</strong>:<input type="password" name="password"><br>
        <input type="submit" value="Login">
    </form>
    <br>
    If you are new user, please <a href="register.html">register</a>.
    </body>
    </html>

`register.html`

### Deployment Descriptor and log4j configuration ###

我们将log4j配置文件方在WEB-INF文件夹中，并将其与应用程序的 WAR 文件打包在一起。

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
    <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false">
        <appender name="dbexample" class="org.apache.log4j.RollingFileAppender">
            <param name="File" value="${catalina.home}/logs/dbexample.log"/>
            <param name="Append" value="true"/>
            <param name="ImmediateFlush" value="true"/>
            <param name="MaxFileSize" value="20MB"/>
            <param name="MaxBackupIndex" value="10"/>
            <layout class="org.apache.log4j.PatternLayout">
                <param name="ConversionPattern" value="%-4r [%t] %-5p %c %x - %m%n"/>
            </layout>
        </appender>
    
        <logger name="com.journaldev" additivity="false">
            <level value="DEBUG"/>
            <appender-ref ref="dbexample"/>
        </logger>
    
        <root>
            <level value="debug"/>
            <appender-ref ref="dbexample"/>
        </root>
    
    </log4j:configuration>

部署描述文件（web.xml）：

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1">
        <display-name>ServletDBLog4jExample</display-name>
        <welcome-file-list>
            <welcome-file>login.html</welcome-file>
        </welcome-file-list>
        <context-param>
            <param-name>dbUser</param-name>
            <param-value>pankaj</param-value>
        </context-param>
        <context-param>
            <param-name>dbPassword</param-name>
            <param-value>pankaj123</param-value>
        </context-param>
        <context-param>
            <param-name>dbURL</param-name>
            <param-value>jdbc:mysql://localhost:3306/UserDB</param-value>
        </context-param>
        <context-param>
            <param-name>log4j-config</param-name>
            <param-value>WEB-INF/log4j.xml</param-value>
        </context-param>
    
        <error-page>
            <error-code>404</error-code>
            <location>/AppErrorHandler</location>
        </error-page>
        <error-page>
            <exception-type>java.lang.Throwable</exception-type>
            <location>/AppErrorHandler</location>
        </error-page>
    
        <filter>
            <filter-name>AuthenticationFilter</filter-name>
            <filter-class>com.journaldev.servlet.filters.AuthenticationFilter</filter-class>
        </filter>
        <filter-mapping>
            <filter-name>AuthenticationFilter</filter-name>
            <url-pattern>/*</url-pattern>
        </filter-mapping>
    </web-app>

注意 web.xml 配置中的以下几点：  
\- welcome-file-list 中提供了 login.html 欢迎文件。  
\- 数据库连接参数是可配置的，并保持为 servlet context init params。  
\- log4j 配置文件的位置也是可配置的，相对位置是作为上下文参数提供的。  
\- 我们的自定义异常处理程序 servler `AppErrorHandler`被配置为处理我们的应用程序代码和404错误抛出的所有异常。  
\- `AuthenticationFilter`配置为过滤到应用程序的所有传入请求，这是我们会话验证的逻辑。

### Model Classes and Database Connection Manager Class ###

User.java 是一个简单的 java bean，它将用户信息保存为会话属性。

package com.journaldev.util;
    
    import java.io.Serializable;
    
    public class User implements Serializable { 
    
        private static final long serialVersionUID = 6297385302078200511L;
    
        private String name;
        private String email;
        private int id;
        private String country;
    
        public User(String nm, String em, String country, int i) {
            this.name = nm;
            this.id = i;
            this.country = country;
            this.email = em;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
    
        public void setEmail(String email) {
            this.email = email;
        }
    
    
        public void setId(int id) {
            this.id = id;
        }
    
        public void setCountry(String country) {
            this.country = country;
        }
    
    
        public String getName() {
            return name;
        }
    
        public String getEmail() {
            return email;
        }
    
        public int getId() {
            return id;
        }
    
        public String getCountry() {
            return country;
        }
    }

`DBConnectionManager.java`是`MySQL`数据库连接的实用工具类，它有一个返回连接对象的方法。我们将使用这个类来进行数据库连接，然后将连接对象设置为其他servlet可以使用的servlet上下文属性。

### Servlet JDBC Example – Context Listener ###

AppContextListener.java是servlet上下文监听器实现，它将在应用程序上下文初始化时初始化数据库连接，并使用配置xml文件配置log4j。注意为数据库连接和log4j配置使用context init params。

当上下文将被销毁时，我们将使用`contextDestroyed()`方法关闭数据库连接。

由于我们使用的是Servlet 3，所以我们不需要在`web.xml`中配置它，我们只需要使用`@WebListener`注解来注释它。

### Exception and Error Handler ###

`AppErrorHandler.java`是我们在配置描述文件中配置的应用程序异常处理程序servlet，它向用户提供有用的信息，包括 404 错误或应用程序级别异常，并提供超链接以转至应用程序的登录页面。

package com.journaldev.servlet.errorhandler;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    @WebServlet("/AppErrorHandler")
    public class AppErrorHandler extends HttpServlet {
        private static final long serialVersionUID = 1L;
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            processError(request, response);
        }
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            processError(request, response);
        }
    
        private void processError(HttpServletRequest request,
                HttpServletResponse response) throws IOException {
            // Analyze the servlet exception
            Throwable throwable = (Throwable) request
                    .getAttribute("javax.servlet.error.exception");
            Integer statusCode = (Integer) request
                    .getAttribute("javax.servlet.error.status_code");
            String servletName = (String) request
                    .getAttribute("javax.servlet.error.servlet_name");
            if (servletName == null) {
                servletName = "Unknown";
            }
            String requestUri = (String) request
                    .getAttribute("javax.servlet.error.request_uri");
            if (requestUri == null) {
                requestUri = "Unknown";
            }
    
            // Set response content type
              response.setContentType("text/html");
    
              PrintWriter out = response.getWriter();
              out.write("<html><head><title>Exception/Error Details</title></head><body>");
              if(statusCode != 500){
                  out.write("<h3>Error Details</h3>");
                  out.write("<strong>Status Code</strong>:"+statusCode+"<br>");
                  out.write("<strong>Requested URI</strong>:"+requestUri);
              }else{
                  out.write("<h3>Exception Details</h3>");
                  out.write("<ul><li>Servlet Name:"+servletName+"</li>");
                  out.write("<li>Exception Name:"+throwable.getClass().getName()+"</li>");
                  out.write("<li>Requested URI:"+requestUri+"</li>");
                  out.write("<li>Exception Message:"+throwable.getMessage()+"</li>");
                  out.write("</ul>");
              }
    
              out.write("<br><br>");
              out.write("<a href=\"login.html\">Login Page</a>");
              out.write("</body></html>");
        }
    }

### Servlet Filter ###

`AuthenticationFilter.java`是我们的`Filter`实现，我们在这里验证用户会话。

package com.journaldev.servlet.filters;
    
    import java.io.IOException;
    
    import javax.servlet.Filter;
    import javax.servlet.FilterChain;
    import javax.servlet.FilterConfig;
    import javax.servlet.ServletException;
    import javax.servlet.ServletRequest;
    import javax.servlet.ServletResponse;
    import javax.servlet.annotation.WebFilter;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    import org.apache.log4j.Logger;
    
    @WebFilter("/AuthenticationFilter")
    public class AuthenticationFilter implements Filter { 
    
        private Logger logger = Logger.getLogger(AuthenticationFilter.class);
    
        public void init(FilterConfig fConfig) throws ServletException {
            logger.info("AuthenticationFilter initialized");
        }
    
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    
            HttpServletRequest req = (HttpServletRequest) request;
            HttpServletResponse res = (HttpServletResponse) response;
    
            String uri = req.getRequestURI();
            logger.info("Requested Resource::"+uri);
    
            HttpSession session = req.getSession(false);
    
            if(session == null && !(uri.endsWith("html") || uri.endsWith("Login") || uri.endsWith("Register"))){
                logger.error("Unauthorized access request");
                res.sendRedirect("login.html");
            }else{
                // pass the request along the filter chain
                chain.doFilter(request, response);
            }
    
    
        }
    
        public void destroy() {
            //close any resources here
        }
    
    }

### Servlet Classes ###

`LoginServlet` 用于验证登录的用户输入，并将其转发到主页或丢失数据，为用户提供有用的信息。

package com.journaldev.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    
    import javax.servlet.RequestDispatcher;
    import javax.servlet.ServletException;
    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 org.apache.log4j.Logger;
    
    import com.journaldev.util.User;
    
    @WebServlet(name = "Login", urlPatterns = {
       "/Login"})
    public class LoginServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;
    
        static Logger logger = Logger.getLogger(LoginServlet.class);
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            String email = request.getParameter("email");
            String password = request.getParameter("password");
            String errorMsg = null;
            if (email == null || email.equals("")) {
                errorMsg = "User Email can't be null or empty";
            }
            if (password == null || password.equals("")) {
                errorMsg = "Password can't be null or empty";
            }
    
            if (errorMsg != null) {
                RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.html");
                PrintWriter out = response.getWriter();
                out.println("<font color=red>" + errorMsg + "</font>");
                rd.include(request, response);
            } else {
    
                Connection con = (Connection) getServletContext().getAttribute("DBConnection");
                PreparedStatement ps = null;
                ResultSet rs = null;
                try {
                    ps = con.prepareStatement("select id, name, email,country from Users where email=? and password=? limit 1");
                    ps.setString(1, email);
                    ps.setString(2, password);
                    rs = ps.executeQuery();
    
                    if (rs != null && rs.next()) {
    
                        User user = new User(rs.getString("name"), rs.getString("email"), rs.getString("country"), rs.getInt("id"));
                        logger.info("User found with details=" + user);
                        HttpSession session = request.getSession();
                        session.setAttribute("User", user);
                        response.sendRedirect("home.jsp");
                        ;
                    } else {
                        RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.html");
                        PrintWriter out = response.getWriter();
                        logger.error("User not found with email=" + email);
                        out.println("<font color=red>No user found with given email id, please register first.</font>");
                        rd.include(request, response);
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                    logger.error("Database connection problem");
                    throw new ServletException("DB Connection problem.");
                } finally {
                    try {
                        rs.close();
                        ps.close();
                    } catch (SQLException e) {
                        logger.error("SQLException in closing PreparedStatement or ResultSet");
                    }
                }
            }
        }
    }

`LogoutServlet`简单地让用户会话失效，并将它们转发到登录页面。

package com.journaldev.servlet;
    
    import java.io.IOException;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.Cookie;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    import org.apache.log4j.Logger;
    
    @WebServlet(name = "Logout", urlPatterns = {
       "/Logout"})
    public class LogoutServlet extends HttpServlet { 
        private static final long serialVersionUID = 1L;
        static Logger logger = Logger.getLogger(LogoutServlet.class);
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            response.setContentType("text/html");
            Cookie[] cookies = request.getCookies();
            if (cookies != null) {
                for (Cookie cookie : cookies) {
                    if (cookie.getName().equals("JSESSIONID")) {
                        logger.info("JSESSIONID=" + cookie.getValue());
                        break;
                    }
                }
            }
            //invalidate the session if exists
            HttpSession session = request.getSession(false);
            logger.info("User=" + session.getAttribute("User"));
            if (session != null) {
                session.invalidate();
            }
            response.sendRedirect("login.html");
        }
    
    }

`RegisterServlet`被用户用来注册到应用程序，然后将它们转发到注册成功消息的登录页面。

package com.journaldev.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.SQLException;
    
    import javax.servlet.RequestDispatcher;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.apache.log4j.Logger;
    
    @WebServlet(name = "Register", urlPatterns = {
       "/Register"})
    public class RegisterServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;
    
        static Logger logger = Logger.getLogger(RegisterServlet.class);
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            String email = request.getParameter("email");
            String password = request.getParameter("password");
            String name = request.getParameter("name");
            String country = request.getParameter("country");
            String errorMsg = null;
            if (email == null || email.equals("")) {
                errorMsg = "Email ID can't be null or empty.";
            }
            if (password == null || password.equals("")) {
                errorMsg = "Password can't be null or empty.";
            }
            if (name == null || name.equals("")) {
                errorMsg = "Name can't be null or empty.";
            }
            if (country == null || country.equals("")) {
                errorMsg = "Country can't be null or empty.";
            }
    
            if (errorMsg != null) {
                RequestDispatcher rd = getServletContext().getRequestDispatcher("/register.html");
                PrintWriter out = response.getWriter();
                out.println("<font color=red>" + errorMsg + "</font>");
                rd.include(request, response);
            } else {
    
                Connection con = (Connection) getServletContext().getAttribute("DBConnection");
                PreparedStatement ps = null;
                try {
                    ps = con.prepareStatement("insert into Users(name,email,country, password) values (?,?,?,?)");
                    ps.setString(1, name);
                    ps.setString(2, email);
                    ps.setString(3, country);
                    ps.setString(4, password);
    
                    ps.execute();
    
                    logger.info("User registered with email=" + email);
    
                    //forward to login page to login
                    RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.html");
                    PrintWriter out = response.getWriter();
                    out.println("<font color=green>Registration successful, please login below.</font>");
                    rd.include(request, response);
                } catch (SQLException e) {
                    e.printStackTrace();
                    logger.error("Database connection problem");
                    throw new ServletException("DB Connection problem.");
                } finally {
                    try {
                        ps.close();
                    } catch (SQLException e) {
                        logger.error("SQLException in closing PreparedStatement");
                    }
                }
            }
    
        }
    
    }

### Home JSP Page ###

`home.jsp`是成功登录后的用户主页，我们只是在这里显示一些用户信息，并提供他们的选项注销。  
`home.jsp`

<%@ page import="com.journaldev.util.User" %>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
    <%User user = (User) session.getAttribute("User"); %>
    <h3>Hi <%=user.getName() %>
    </h3>
    <strong>Your Email</strong>: <%=user.getEmail() %><br>
    <strong>Your Country</strong>: <%=user.getCountry() %><br>
    <br>
    <form action="Logout" method="post">
        <input type="submit" value="Logout">
    </form>
    </body>
    </html>

JSP 页面仍然包含很多 Java 代码，因为我们没有使用 JSP 标签，我们将在 JSP 教程中对此进行研究。目前请忍受这一点。

### Run the Servlet JDBC Example Application ###

我们的应用程序已准备好执行，我建议将其导出为 WAR 文件，然后部署到 Tomcat，而不是直接从 IDEA 部署到 Tomcat服务器，以便您可以轻松查看 log4j 日志文件进行调试。

一些示例执行页面显示在下面的图像中。

**User Registration Page:**  
![这里写图片描述][SouthEast 1]  
**Registration Success Page:**  
![这里写图片描述][SouthEast 2]  
**Login Page:**  
![这里写图片描述][SouthEast 3]  
**User Home Page:**  
![这里写图片描述][SouthEast 4]  
**404 Error Page:**  
这里自动跳转至 `login.jsp` 和上文描述不符。  
**Input Validation Error Page:**  
![这里写图片描述][SouthEast 5]  
log4j Log File:

0    [RMI TCP Connection(5)-127.0.0.1] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - AuthenticationFilter initialized
    0    [RMI TCP Connection(5)-127.0.0.1] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - AuthenticationFilter initialized
    547  [http-nio-8080-exec-1] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/
    547  [http-nio-8080-exec-1] ERROR com.journaldev.servlet.filters.AuthenticationFilter  - Unauthorized access request
    547  [http-nio-8080-exec-2] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/login.html
    562  [http-nio-8080-exec-3] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/
    562  [http-nio-8080-exec-3] ERROR com.journaldev.servlet.filters.AuthenticationFilter  - Unauthorized access request
    562  [http-nio-8080-exec-4] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/login.html
    1578 [http-nio-8080-exec-5] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/
    1578 [http-nio-8080-exec-5] ERROR com.journaldev.servlet.filters.AuthenticationFilter  - Unauthorized access request
    1625 [http-nio-8080-exec-6] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/login.html
    3947 [http-nio-8080-exec-7] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/register.html
    14154 [http-nio-8080-exec-8] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/Register
    14170 [http-nio-8080-exec-8] INFO  com.journaldev.servlet.RegisterServlet  - User registered with email=oktfolio@gmail.com
    22664 [http-nio-8080-exec-10] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/Login
    22664 [http-nio-8080-exec-10] ERROR com.journaldev.servlet.LoginServlet  - User not found with email=oktfolio@gmail.com
    31341 [http-nio-8080-exec-9] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/Login
    31341 [http-nio-8080-exec-9] INFO  com.journaldev.servlet.LoginServlet  - User found with details=com.journaldev.util.User@5fd7c717
    31356 [http-nio-8080-exec-1] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/home.jsp
    33684 [http-nio-8080-exec-2] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/Logout
    33684 [http-nio-8080-exec-2] INFO  com.journaldev.servlet.LogoutServlet  - JSESSIONID=FF9C66D2C9893445066334DE8826DBBE
    33684 [http-nio-8080-exec-2] INFO  com.journaldev.servlet.LogoutServlet  - User=com.journaldev.util.User@5fd7c717
    33684 [http-nio-8080-exec-3] INFO  com.journaldev.servlet.filters.AuthenticationFilter  - Requested Resource::/login.html

我希望你喜欢这篇文章，并理解Servlet JDBC和Log4j集成的核心概念。

[SouthEast]: /images/20220601/434cc1835e224de5aea5332954fb0ff2.png
[SouthEast 1]: /images/20220601/eb29e01538a24e98a057a13b06820565.png
[SouthEast 2]: /images/20220601/ace17b8ca72647f1a0646bdf6a33f6c3.png
[SouthEast 3]: /images/20220601/d2a9edf67bee47419961eef8fff71631.png
[SouthEast 4]: /images/20220601/be8a9e0a53244b978be17329ac5f62f6.png
[SouthEast 5]: /images/20220601/5fd1ece5f98c4e0f90ba1f103e516d00.png