1、JavaWeb 實現登錄注冊（超詳細附代碼）前相信剛學Javaweb的伙伴第個接觸的個項都是從項的登錄注冊開始的。 下個項中的登錄注冊將會帶家從零開始學習怎么設計登錄注冊流程.登錄注冊設計流程注冊的數據流程那么我們的前端數據是怎么傳向后端的？ 1.先這我們是 表單傳遞 通過form提交2.在這，我們輸的姓名和密碼，點擊注冊按鈕。此時輸的這三個數據，我們可以看做成是個表單的數據，這些數據會提交到服務器上：3.此時，個叫Tomcat的東西會處理這個請求，4.得到請求之后，Tomcat會將這個請求交由Servlet來進處理5.Servlet調Dao層寫的各種實現法，與數據庫進交互（curd調仔）那么

2、下就是注冊操作的主要調流程圖register.jspregistServletUserDB第步第步第三步4.登錄的數據流程登錄操作的主要調流程圖Login.jspLoginServletUserDB第步第步第三步第四步部分代碼的展register.jsp注冊頁 通過表單實現跳轉到servlet123456789world message board of the future10 11 1213Register14 15 16 171819202122232425 26 27 28 2930 31 32 33 3435$message36 37 38 39 40 復制代碼RegisterSer

3、vlet.java業務層：處理注冊業務12package Sevlet;3import java.io.IOException;4import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http

4、.HttpSession;567891011 import javaBean.User;12 import useBean.UserDB;1314 WebServlet(/RegistServlet)15 public class RegistServlet extends HttpServlet 16 private static final long serialVersionUID = 1L;17 String message =;17 String message =;1819202122public RegistServlet() super();23 protected void

5、doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 242526272829303132request.setCharacterEncoding(utf-8);/獲取隱藏域的信息String action = request.getParameter(action);String url =register.jsp;if(action.equals(regist)url = registerUser(request,response);getS

6、ervletContext().getRequestDispatcher(url).forward(request, response);33 /注冊函數34 private String registerUser(HttpServletRequest request,HttpServletResponse response) 3536373839404142434445464748495051525354555657585960616263646566676869707172String username = request.getParameter(username);String pas

7、sword = request.getParameter(password);String password2 = request.getParameter(password2);String message = ;/HttpSession類型的對象HttpSession session = request.getSession();/User對象User user = new User();user.setusername (username);user.setpassword(password);String url = /login.jsp;if(password.equals(pass

8、word2)if( !UserDB.UserExists(username) ) message = Registration successful! and login in;session.setAttribute(message, message);/將注冊戶信息寫數據庫UserDB.insert(user);return url;elsemessage = The user name already exists;url = /register.jsp;session.setAttribute(message, message);return url;elsemessage = The

9、 password is inconsistent;session.setAttribute(message, message);url = /register.jsp;return url;73 復制代碼Dao層實現判斷戶名是否存在和插數據庫的法 UserDB.java12/注冊時判斷戶名是否存在public static boolean UserExists(String username) /可以建個連接池保存定數量的連接，當有對象需要數據庫連接時，直接將這個連接返回給該對象，ConnectionPool pool = ConnectionPool.getInstance();Conne

10、ction connection = pool.getConnection();PreparedStatement ps = null;34567ResultSet rs = null;89String qr = SELECT username FROM User + WHERE username = ?;101112131415161718192021222324try ps = connection.prepareStatement(qr);ps.setString(1, username);rs = ps.executeQuery();return rs.next(); catch (S

11、QLException e) System.out.println(e);return false; finally DBUtil.closeResultSet(rs);DBUtil.closePreparedStatement(ps);pool.freeConnection(connection);25 /將注冊戶信息保存數據庫26 public static int insert(User user) 27282930313233343536373839404142434445464748ConnectionPool pool = ConnectionPool.getInstance();

12、Connection connection = pool.getConnection();PreparedStatement ps = null;String qr = INSERT INTO User (username, password)+VALUES (?, ?);try ps = connection.prepareStatement(qr);ps.setString(1, user.getusername();ps.setString(2, user.getpassword();return ps.executeUpdate(); catch (SQLException e) Sy

13、stem.out.println(e);return 0; finally DBUtil.closePreparedStatement(ps);pool.freeConnection(connection);49 復制代碼login.jsp登錄界 通過表單實現跳轉到servlet12345world message board of the future67891011 12 1314login15 16 171819202122232425262728 2930register31 32 33 3435$message36 37 38 39 40 復制代碼LoginServlet.java

14、業務層：處理登錄業務123456789package Sevlet;import java.io.IOException;import java.util.List;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;10 import javax.servlet.http.HttpServletRequest;11 import javax.s

15、ervlet.http.HttpServletResponse;12 import javax.servlet.http.HttpSession;1314 import javaBean.Message;15 import javaBean.User;16 import useBean.UserDB;17 /*18 * Servlet implementation class Login19 */20 WebServlet(/LoginServlet)/LoginServlet完整路徑21 public class LoginServlet extends HttpServlet 22 pri

16、vate static final long serialVersionUID = 1L;23 String message=;/定義個變量24252627public LoginServlet() super();28 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 2930313233343536373839404142434445String url =/login.jsp;String action =

17、 request.getParameter(action);System.out.println(action: + action);/ 打印測試/設置編碼request.setCharacterEncoding(utf-8);/檢測頁是否完成提交if(action = null)url=/login.jsp;else if(action.equals(login)/login()函數返回個路徑url = login(request,response);/設置登是否成功的提信息request.setAttribute(message, message);/forward()法，轉發請求getS

18、ervletContext().getRequestDispatcher(url).forward(request, response);46 /login()函數47 private String login(HttpServletRequest request, HttpServletResponse response) 484950515253545556575859606162636465666768697071727374757677787980818283/()String username = request.getParameter(username);String passw

19、ord = request.getParameter(password);/HttpSession類型的對象HttpSession session = request.getSession();String userid=;/user的信息User user = UserDB.selectUser(username);String url = /register.jsp;if(user != null) /,較密碼if(user.getpassword().equals(password) /于記錄該戶狀態/cookie加戶名Cookie u = new Cookie(userid,usern

20、ame);/設置有效期u.setMaxAge(60*60*24*365*2);/設置路徑u.setPath(/);/cookie加瀏覽器response.addCookie(u);userid = user.getid();session.setAttribute(userid, userid);/selectUmessage表中讀出所有數據List mL = UserDB.selectU();/ml信息request.setAttribute(MessageList, mL);url=/MessageList.jsp;else message = Wrong password;url=/lo

21、gin.jsp;848586878889909192else message = The user does not exist;url = /login.jsp;return url;93 復制代碼UserDB.java Dao層實現查找戶的法DB.java123/usernameuserpublic static User selectUser(String username) 4/可以建個連接池保存定數量的連接，當有對象需要數據庫連接時，直接將這個連接返回給該對象，5ConnectionPool pool = ConnectionPool.getInstance();6Connection connection = pool.getConnection();7PreparedSta