Servlet 不重定向到 JSP 页面
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【中文标题】Servlet 不重定向到 JSP 页面【英文标题】：Servlet not directing to JSP page 【发布时间】：2014-12-05 18:56:26 【问题描述】：我们需要使用 Java、html、Bean 和 JSP 编写 Web 应用程序。问题是我从未上过 HTML 或 CSS 课程。
我有一个名为 index.html 的基本 HTML 页面，它在带有提交按钮的文本字段中获取用户的名字和姓氏。当我按下提交时，我收到“页面无法显示错误”。我已经将我的代码与我的导师进行了比较，它非常相似，所以我不确定我做错了什么。任何帮助将不胜感激。
另外，不要介意我可怕的格式。
index.html
<!DOCTYPE html>
<html>
<head>
<title>Final Project</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<h1>Welcome to Banking by Tyler Weaver</h1>
<h4>Please Enter your First and Last Name</h4>
<form action="BankingControl" method="POST">
<input type="hidden" name="action" value="Menu">
First Name:
<input type="text" name="FirstName" required/> <br></>
Last Name:
<input type="text" name="LastName" required/> <br></>
<input type="submit" value="Login"/>
</form>
</body>
</html>
BankingControl.java
import beans.User;
import database.mysql;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.logging.Level;
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 utilities.ErrorLogger;
@WebServlet(name = "BankingControl", urlPatterns = "/BankingControl")
public class BankingControl extends HttpServlet
private static final String mysqlPrefix = "jdbc:mysql://";
private static final String hostname = "cs3db.bloomu.edu";
private static final String databaseName = "CS3";
private static final String databaseURL = mysqlPrefix + hostname + "/" + databaseName;
private static final String userName = "tgw46366";
private static final String password = "tgw46366";
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
response.setContentType("text/html;charset=UTF-8");
//Creates mysql database connection with specified information
MySQL mysql = new MySQL(databaseURL, userName, password);
//The URL where processor will send.
String JSP_URL = "/index.html";
//Tries making a connection to the database
try (Connection conn = mysql.getConnection())
ErrorLogger.log(Level.INFO, "Database Connection Obtained");
//Retrieve action from page
String action = request.getParameter("action").trim();
//If action is null, make it menu
if (action == null)
action = "Menu";
User user = new User();
user.setFirstName(request.getParameter("firstName").trim());
user.setLastName(request.getParameter("lastName").trim());
request.setAttribute("User", user);
//Check to see if action is menu
if (action.equalsIgnoreCase("Menu"))
//Place to send information
JSP_URL = "/Menu.jsp";
ErrorLogger.log(Level.INFO, "User " + user.getFirstName() + " "
+ user.getLastName()
+ " logged in - Menu Page Returned");
else if (action.equalsIgnoreCase("NewCustomer"))
JSP_URL = "/NewCustomer.jsp";
ErrorLogger.log(Level.INFO, "New Customer Selected");
else if (action.equalsIgnoreCase("NewAccount"))
JSP_URL = "/NewAccount.jsp";
ErrorLogger.log(Level.INFO, "New Account Selected");
else if (action.equalsIgnoreCase("AccountTransaction"))
JSP_URL = "/Transaction.jsp";
ErrorLogger.log(Level.INFO, "Account Transaction Selected");
else if (action.equalsIgnoreCase("Logout"))
JSP_URL = "/index.html";
ErrorLogger.log(Level.INFO, "Logout Selected");
else
ErrorLogger.log(Level.WARNING,
"Invalid Option -- index.html Returned");
//If connection cannot be made, throw here
catch (SQLException ex)
ErrorLogger.log(Level.SEVERE,
"Not Making a Database Connection at this Time", ex);
//forward to correct JSP
getServletContext()
.getRequestDispatcher(JSP_URL)
.forward(request, response);
@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";
MySQL.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.logging.Level;
import utilities.ErrorLogger;
public class MySQL
private final String databaseURL;
private final String userName;
private final String password;
public MySQL(String databaseURL, String userName, String password)
this.databaseURL = databaseURL;
this.userName = userName;
this.password = password;
initDB();
private void initDB()
try
Class.forName("com.mysql.jdbc.Driver").newInstance(); //Not needed for MySQL - here for show only
catch (ClassNotFoundException ex)
ErrorLogger.log(Level.SEVERE, "Could not find the class com.mysql.jdbc.Driver \n"
+ "Program will now exit. ", ex);
System.exit(1);
catch (InstantiationException ex)
ErrorLogger.log(Level.SEVERE, "Could not instaniate the class com.mysql.jdbc.Driver \n"
+ "Program will now exit. ", ex);
System.exit(1);
catch (IllegalAccessException ex)
ErrorLogger.log(Level.SEVERE, "Could not access the class com.mysql.jdbc.Driver \n"
+ "Program will now exit. ", ex);
System.exit(1);
try
Connection conn = DriverManager.getConnection(databaseURL, userName, password);
conn.close();
catch (SQLException ex)
ErrorLogger.log(Level.SEVERE, "Could not connect to the database. "
+ "Database string = "
+ databaseURL + " user = " + userName + " password " + password, ex);
System.exit(1);
public Connection getConnection()
Connection conn = null;
try
conn = DriverManager.getConnection(databaseURL, userName, password);
catch (SQLException e)
ErrorLogger.log(Level.SEVERE, "Could not connect to the database. "
+ "Database string = "
+ databaseURL + " user = " + userName + " password " + password);
System.exit(1);
return conn;
public void closeConnection(Connection connection)
if (connection != null)
try
connection.close();
catch (SQLException e)
ErrorLogger.log(Level.SEVERE, "SQL Exception is thrown while "
+ "trying to close a Connection object. The connection "
+ "object was not null.", e);
ErrorLogger.java
import java.io.IOException;
import java.sql.Date;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.logging.FileHandler;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.Logger;
public class ErrorLogger
private static final String errorFileName = "SQLErrorLogger";
public static boolean showLogInErrorWindow = true;
private static Logger errorLogger;
private static void initializeLogging() throws IOException
String logFile = getLogfileName();
errorLogger = Logger.getLogger(logFile);
Handler handler = new FileHandler(logFile);
handler.setFormatter(new java.util.logging.SimpleFormatter());
if (showLogInErrorWindow)
errorLogger.setUseParentHandlers(true);
else
errorLogger.setUseParentHandlers(false);
errorLogger.addHandler(handler);
private static String getFormattedDate(Date date)
DateFormat format;
format = new SimpleDateFormat("MM-dd-yyyy");
return (format.format(date));
private static String getFormattedTime(Date date)
DateFormat format;
format = new SimpleDateFormat("hh.mm.a");
return (format.format(date));
private static String getDateTime(Date date)
String sDateTime = getFormattedDate(date) + "_"
+ getFormattedTime(date);
return sDateTime;
private static String getLogfileName()
String logFileName = errorFileName;
Date date = new Date(System.currentTimeMillis());
String sFormattedDateTime = getDateTime(date);
logFileName += "_" + sFormattedDateTime;
logFileName += ".log";
return logFileName;
public static String getNewLogFileName(String logFileBase, String logFileExt)
String logFile = logFileBase;
Date date = new Date(System.currentTimeMillis());
String sFormattedDateTime = getDateTime(date);
logFile += "_" + sFormattedDateTime;
logFile += logFileExt;
return logFile;
public static void log(Level level, String message, Throwable ex)
if (errorLogger == null)
initLogger();
errorLogger.log(level, message, ex);
public static void log(Level level, String message)
if (errorLogger == null)
initLogger();
errorLogger.log(level, message);
private static void initLogger()
try
initializeLogging();
catch (IOException ex)
errorLogger = Logger.getLogger(getLogfileName());//Will not write to a file
errorLogger.log(Level.SEVERE, "Could not create a file handler for teh error logger");
public static void main(String[] args)
ErrorLogger.log(Level.SEVERE, "Test error Message");
除了示例数据库和信息之外，这应该是重现错误的最低要求。所有 JSP 页面都单独加载，但它不会从 index.html 开始。这使得调试应用程序的其余部分变得困难。任何帮助将不胜感激。
目录：
错误图片！
【问题讨论】：
您应该提供完整的 web.xml 以及错误的含义（检查控制台 - 服务器返回错误或浏览器根本不想连接）。伙计们，请尽最小的努力！ 我想看看你可能拥有的目录结构和其他控制器。您正在重定向到一个资源，但我不知道该资源是否与 root 位于同一目录中，还是位于其他位置？干杯。 @MichalWilkowski 如何显示 web.xml？我将在上面列出我的目录结构！ 顺便说一句，当从 index.html 转到 jsp 时，您的 url 是否如您所愿？我有一种感觉，你的转发是相对的而不是绝对的，所以它实际上发送到一个不正确的 url。 我从 index.html 转到 BankingControl servlet，它将把它定向到一个 jsp。在使用相同结构时，我将 URL 完全按照我的导师放置的方式记录下来。 【参考方案1】：只是在这里给出一个答案，以防有人遇到这个问题。问题是由于缺少 jars 而发生的内部服务器错误。
【讨论】：
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