servletbean.java
package com.bean;
import java.io.IOException;
import java.sql.*;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class servletbean
*/
@WebServlet("/servletbean")
public class servletbean extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html;charset=UTF-8");
String id=request.getParameter("userm");
String pwd=request.getParameter("pwd");
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); //驱动程序名
String username="saa";
String password="123";
String url="jdbc:sqlserver://localhost:1433;databaseName=gaokao";
Connection conn = DriverManager.getConnection(url,username,password);
if (conn != null) {
response.getWriter().print("数据库连接成功！");
response.getWriter().print("<br />");
Statement stmt = null;
ResultSet rs = null;
stmt = conn.createStatement();
String sql = "SELECT * FROM user where username='"+id+"' and password='"+pwd+"'"; //查询语句
rs = stmt.executeQuery(sql);
response.getWriter().print("查询结果：");
response.getWriter().print("<br />");
boolean isTrue=false;
Bean user=new Bean();
while (rs.next()) {
isTrue=true;
//将查询结果输出
user.setUsername(rs.getString(1));
user.setPassword(rs.getString(2));
user.setSex(rs.getString(3));
user.setRank(rs.getString(4));
}
if(isTrue) {
request.getSession().setAttribute("user",user);
response.sendRedirect("../hello1.jsp");
}
} else {
response.sendRedirect("../error1.jsp");
}
} catch (Exception e) {
response.getWriter().print("数据库连接异常！" + e.getStackTrace().toString());
}
}
}
hello1.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" import="com.bean.Bean"
pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
<title>hello</title>
</head>
<body>
<%
Bean user=(Bean)session.getAttribute("user");
%>
<% out.println(user); %>
<%=user.getUsername() %>
<%=user.getPassword() %>
<%=user.getSex() %>
<%=user.getRank() %>
</body>
</html>
login1.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="java.sql.*" %>
<!DOCTYPE html>
<html>
<head>
<title>Insert title here</title>
</head>
<body>
<form action="../servletbean" method="post">
用户名：<input type="text" name="userm">
密码：<input type="password" name="pwd">
<input type="submit" name="登录">
</form>
</body>
</html>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<display-name>LoginS</display-name>
<welcome-file-list>
<welcome-file>login1</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>servletbean.java</servlet-name>
<servlet-class>com.bean</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>servletbean.java</servlet-name>
<url-pattern>/Login.html</url-pattern>
</servlet-mapping>
</web-app>
为啥会出现这样的错误，求解🙏
