Jsp+Servlet实现简单登录注册查询（jsp作用域有哪些）这样也行？

public class UserDao { private Connection conn=null; private PreparedStatement ps=null; private int result=0; private ResultSet rs=null; //用户注册 public int register(User user){ String sql=”insert into users(name,password,age) value (?,?,?)”; try { //获取数据库连接对象 conn=JDBCUtil.getConnection(); //获取数据库操作对象 ps=conn.prepareStatement(sql); ps.setString(1,user.getName()); ps.setString(2,user.getPassword()); ps.setInt(3,user.getAge()); //执行sql result=ps.executeUpdate(); } catch (Exception e) { e.printStackTrace(); }finally { JDBCUtil.close(null,ps,conn); } return result; } //登录验证用户信息 public int login(String userName,String password){ String sql=”select count(*) from users where name=? and password=?”; try { conn=JDBCUtil.getConnection(); ps=conn.prepareStatement(sql); ps.setString(1,userName); ps.setString(2,password); rs=ps.executeQuery(); while (rs.next()){ result=rs.getInt(“count(*)”); } } catch (Exception e) { e.printStackTrace(); } finally { JDBCUtil.close(rs,ps,conn); } return result; } //根据用户名 显示用户名、密码、年龄 public User findByName(String userName){ String sql=”select name,password,age from users where name=?”; User user=null; try { conn=JDBCUtil.getConnection(); ps=conn.prepareStatement(sql); ps.setString(1,userName); rs=ps.executeQuery(); while (rs.next()){ String name=rs.getString(“name”); String password=rs.getString(“password”); int age=rs.getInt(“age”); user=new User(name,password,age); } } catch (Exception e) { e.printStackTrace(); }finally { JDBCUtil.close(null,ps,conn); } return user; } }

public class User { private int id; private String name; private String password; private int age; //set… //get… //constructor… }

public class UserServiceImpl implements UserService { UserDao userDao=new UserDao(); // 注册 @Override public int register(User user) { return userDao.register(user); } // 登陆 @Override public int login(String userName, String password) { return userDao.login(userName,password); } // 根据用户名查找信息 @Override public User findByName(String userName) { return userDao.findByName(userName); } }

// FindByNameServlet public class FindByNameServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String name=request.getParameter(“name”); UserService userService=new UserServiceImpl(); User user=userService.findByName(name); //将查询结果放入request作用域 request.setAttribute(“userInfo”,user); request.getRequestDispatcher(“/jsp/index.jsp”).forward(request,response); } } // LoginServlet public class LoginServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1 获取 String userName=request.getParameter(“userName”); String password=request.getParameter(“password”); //2 service调用dao对数据库操作 UserService userService=new UserServiceImpl(); int result=userService.login(userName, password); //3 成功跳转到查询页面，失败跳转到失败页面 if (result>0){ response.sendRedirect(“/jsp/index.jsp”); }else{ response.sendRedirect(“/login_error.html”); } } } // RegisterServlet public class RegisterServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { UserService userService=new UserServiceImpl(); User user=null; int result=0; //1【调用请求对象】读取【请求头】参数信息，得到用户注册信息 String userName, password, age; userName=request.getParameter(“userName”); password=request.getParameter(“password”); age=request.getParameter(“age”); user=new User(userName, password, Integer.valueOf(age)); //2 调用userService——>userDao // 先查询用户是否存在 User byName=userService.findByName(userName); if (byName!=null){ request.setAttribute(“info”,”用户已存在！”); request.getRequestDispatcher(“/jsp/register.jsp”).forward(request,response); } // 注册 result=userService.register(user); //3 设置编码格式，防止乱码 response.setContentType(“text/html;charset=utf-8”); PrintWriter out=response.getWriter(); //注册成功：——>跳转至登录页面进行登录 //注册失败：——>注册页面提示：注册失败 if (result==1) { response.sendRedirect(“/login.html”); } else { request.setAttribute(“info”,”注册失败！”); request.getRequestDispatcher(“/jsp/register.jsp”).forward(request,response); } } }

public class JDBCUtil { private JDBCUtil(){} //静态代码块在类加载时执行，并且执行一次。 static{ try { Class.forName(“com.mysql.cj.jdbc.Driver”); } catch (ClassNotFoundException e) { e.printStackTrace(); } } //获取数据库连接对象 public static Connection getConnection() throws Exception{ String url=”jdbc:mysql://127.0.0.1:3306/zy?&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true”; String user=”root”; String password=”rootroot”; return DriverManager.getConnection(url,user,password); } public static void close(ResultSet rs, Statement ps, Connection conn){ if (rs !=null) { try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } } if (ps !=null) { try { ps.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn !=null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } }

<%@ page import=”entity.User” %> <%@ page contentType=”text/html;charset=UTF-8″ language=”java” %> <html> <head> <title>查询页面</title> </head> <body> <div align=”center”> <h2/>输入用户名，查询信息 <form action=”/findByName” method=”get”> <input type=”text” name=”name” id=”name”> <input type=”submit” value=”查询”> </form> <% User userInfo=(User) request.getAttribute(“userInfo”); %> <% if (userInfo !=null) { %> <table border=”3″> <tr> <th>用户名</th> <th>密码</th> <th>年龄</th> </tr> <tr> <td>     <%=userInfo.getName()%>    </td> <td>     <%=userInfo.getPassword()%>    </td> <td>     <%=userInfo.getAge()%>    </td> </tr> </table> <% } %> </div> </body> </html>

<%@ page import=”com.mysql.cj.util.StringUtils” %> <%@ page contentType=”text/html;charset=UTF-8″ language=”java” %> <html> <head> <title>Title</title> </head> <body> <br> <br> <% String info=(String) request.getAttribute(“info”); %> <% if (!StringUtils.isNullOrEmpty(info)){ %> <h1 style=”color: red;text-align: center” ><%=info%></h1> <% } %> <div align=”center”> <form action=”/register” method=”post”> <table border=”2″> <tr> <th>用户名</th> <td><input type=”text” name=”userName”/></td> </tr> <tr> <th>密码</th> <td><input type=”password” name=”password”/></td> </tr> <tr> <th>年龄</th> <td><input type=”text” name=”age”/></td> </tr> <tr> <td colspan=”2″ align=”center”> <input type=”submit” value=”注册”/> <input type=”reset” value=”清空”/> </td> </tr> </table> </form> </div> </body> </html>

<?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_4_0.xsd” version=”4.0″> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>servlet.LoginServlet</servlet-class> </servlet> <servlet> <servlet-name>RegisterServlet</servlet-name> <servlet-class>servlet.RegisterServlet</servlet-class> </servlet> <servlet> <servlet-name>FindByNameServlet</servlet-name> <servlet-class>servlet.FindByNameServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/login</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>RegisterServlet</servlet-name> <url-pattern>/register</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>FindByNameServlet</servlet-name> <url-pattern>/findByName</url-pattern> </servlet-mapping> <!–设置默认欢迎文件规则–> <welcome-file-list> <welcome-file>login.html</welcome-file> <!–servlet 作为默认欢迎文件 ‘/’需要去掉–> </welcome-file-list> </web-app>

<!DOCTYPE html> <html lang=”en”> <head> <meta charset=”UTF-8″> <title>登陆界面</title> </head> <body> <div align=”center”> <font size=”10px” color=”#00008b”>用户登录</font> <form action=”/login” method=”post”> <table border=”2″> <tr> <th>用户名</th> <td><input type=”text” name=”userName”/></td> </tr> <tr> <th>密码</th> <td><input type=”password” name=”password”/></td> </tr> <tr> <td colspan=”2″ align=”center”> <input type=”submit” value=”登录”/> <input type=”reset” /> </td> </tr> </table> </form> <a href=”https://www.jb51.net/jsp/register.jsp” style=”text-align: left”>立即注册</a> </div> </body> </html>

<!DOCTYPE html> <html lang=”en”> <head> <meta charset=”UTF-8″> <title>登录验证</title> </head> <body> <div align=”center”> <font size=”10px” color=”#00008b”>用户登录</font><br> <font size=”5px” color=”red”>登录信息不存在，请重新登陆！！！</font> <form action=”/login” method=”post”> <table border=”2″> <tr> <th>用户名</th> <td><input type=”text” name=”userName” /></td> </tr> <tr> <th>密码</th> <td><input type=”password” name=”password” /></td> </tr> <tr> <td colspan=”2″ align=”center”> <input type=”submit” value=”登录”/> <input type=”reset”> </td> </tr> </table> </form> <a href=”https://www.jb51.net/jsp/register.jsp” style=”text-align: left”>立即注册</a> </div> </body> </html>

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