Servlet不会重定向到JSP页面

时间：2014-12-05 18:56:27

标签： java html jsp servlets jdbc

我们需要使用Java，HTML，Beans和JSP编写Web应用程序。问题是我从未参加过HTML或CSS课程。

我有一个名为index.html的基本HTML页面，它使用提交按钮在文本字段中获取用户的名字和姓氏。当我按提交时，我收到“页面无法显示错误”。我把我的代码与我的教师进行了比较，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化。

的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，这应该是重现错误所需的最低要求。所有JSP页面都单独加载，但不会从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。

指南：Director img

错误图片！First image

ErrorImage

1 个答案:

答案 0 :(得分：1)

只是在这里给出答案以防万一有人遇到这个问题。问题是由于丢失jar而发生内部服务器错误。

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