0
我正在嘗試爲網站創建登錄頁面（我現在正在使用教程 - 以前從未這樣做過）。當我去使用「登錄」頁面時，它彈出404錯誤。這是代碼。JSP登錄頁面無法正常工作
LoginPage.jsp
<%@ page language="java"
contentType="text/html; charset=windows-1256"
pageEncoding="windows-1256"
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1256">
<title>Login Page</title>
</head>
<body>
<form action="LoginServlet">
Please enter your username
<input type="text" name="un"/><br>
Please enter your password
<input type="text" name="pw"/>
<input type="submit" value="submit">
</form>
</body>
</html>
LoginServlet.java
package ExamplePackage;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* Servlet implementation class LoginServlet
*/
public class LoginServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
try
{
UserBean user = new UserBean();
user.setUserName(request.getParameter("un"));
user.setPassword(request.getParameter("pw"));
user = UserDAO.login(user);
if (user.isValid())
{
HttpSession session = request.getSession(true);
session.setAttribute("currentSessionUser",user);
response.sendRedirect("userLogged.jsp"); //logged-in page
}
else
response.sendRedirect("invalidLogin.jsp"); //error page
}
catch (Throwable theException)
{
System.out.println(theException);
}
}
}
UserBean.Java
package ExamplePackage;
public class UserBean {
private String username;
private String password;
private String firstName;
private String lastName;
public boolean valid;
public String getFirstName() {
return firstName;
}
public void setFirstName(String newFirstName) {
firstName = newFirstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String newLastName) {
lastName = newLastName;
}
public String getPassword() {
return password;
}
public void setPassword(String newPassword) {
password = newPassword;
}
public String getUsername() {
return username;
}
public void setUserName(String newUsername) {
username = newUsername;
}
public boolean isValid() {
return valid;
}
public void setValid(boolean newValid) {
valid = newValid;
}
}
UserDAO.java
package ExamplePackage;
import java.text.*;
import java.util.*;
import java.sql.*;
public class UserDAO
{
static Connection currentCon = null;
static ResultSet rs = null;
public static UserBean login(UserBean bean) {
//preparing some objects for connection
Statement stmt = null;
String username = bean.getUsername();
String password = bean.getPassword();
String searchQuery =
"select * from users where username='"
+ username
+ "' AND password='"
+ password
+ "'";
// "System.out.println" prints in the console; Normally used to trace the process
System.out.println("Your user name is " + username);
System.out.println("Your password is " + password);
System.out.println("Query: "+searchQuery);
try
{
//connect to DB
currentCon = ConnectionManager.getConnection();
stmt=currentCon.createStatement();
rs = stmt.executeQuery(searchQuery);
boolean more = rs.next();
// if user does not exist set the isValid variable to false
if (!more)
{
System.out.println("Sorry, you are not a registered user! Please sign up first");
bean.setValid(false);
}
//if user exists set the isValid variable to true
else if (more)
{
String firstName = rs.getString("FirstName");
String lastName = rs.getString("LastName");
System.out.println("Welcome " + firstName);
bean.setFirstName(firstName);
bean.setLastName(lastName);
bean.setValid(true);
}
}
catch (Exception ex)
{
System.out.println("Log In failed: An Exception has occurred! " + ex);
}
//some exception handling
finally
{
if (rs != null) {
try {
rs.close();
} catch (Exception e) {}
rs = null;
}
if (stmt != null) {
try {
stmt.close();
} catch (Exception e) {}
stmt = null;
}
if (currentCon != null) {
try {
currentCon.close();
} catch (Exception e) {
}
currentCon = null;
}
}
return bean;
}
}
ConnectionManager.java
package ExamplePackage;
import java.sql.*;
import java.util.*;
public class ConnectionManager {
static Connection con;
static String url;
public static Connection getConnection()
{
try
{
String url = "jdbc:odbc:" + "logindb";
// assuming "DataSource" is your DataSource name
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
try
{
con = DriverManager.getConnection(url,"root","root");
// assuming your SQL Server's username is "username"
// and password is "password"
}
catch (SQLException ex)
{
ex.printStackTrace();
}
}
catch(ClassNotFoundException e)
{
System.out.println(e);
}
return con;
}
}
錯誤：
HTTP Status [404] – [Not Found]
Type Status Report
Message /LoginExample/LoginServlet
Description The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.
Apache Tomcat/9.0.0.M21
圍棋，並在網上辦理登機手續的servlet的Hello World程序，並努力實踐它，回來這個應用程序...這是初學者的好方法... – VNT