基于servlet的登陆验证并实现增删改查、验证码等功能

package logic; import java.io.IOException; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import model.User; public class LoginServlet extends HttpServlet { @Override public void init() throws ServletException { List<User> users = (List<User>) getServletContext().getAttribute("USERS"); if(users == null) { users = new ArrayList<User>(); //这里初始化产生用户 users.add(new User("Jay","111",true)); users.add(new User("Linda","111",false)); users.add(new User("Tom","111",true)); users.add(new User("Jack","111",false)); users.add(new User("Rose","111",true)); users.add(new User("Jim","111",false)); users.add(new User("Bob","111",true)); users.add(new User("Logen","111",true)); users.add(new User("Kobe","111",false)); getServletContext().setAttribute("USERS", users); } } @Override public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req,resp); } @Override public void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { HttpSession session = req.getSession(); String username = req.getParameter("username"); String password = req.getParameter("password"); String strCode = req.getParameter("code"); String savedCode = (String)session.getAttribute("code"); String ret = ""; if("".equals(username)) { ret = "emptyErr";//空用户名错误 } else if("".equals(password)) { ret = "passEmptyErr";//空密码错误 } else if("".equals(strCode)) { ret = "codeEmptyErr";//空验证码错误 } else if(!strCode.equals(session.getAttribute("code"))) { ret = "codeErr";//验证码输入错误 } else{ User user = new User(ret, ret, false); user.setName(username); user.setPassword(password); List<User> users = (List<User>) getServletContext().getAttribute("USERS"); boolean bFound = false; for(User u : users) { if(u.equals(user)) { bFound = true; if(u.getPassword().equals(user.getPassword())) { if(u.getAdmin()) ret = "admin"; else ret = "user"; } else ret = "passwordErr"; break; } } if(!bFound) ret = "userNotExits"; } if("emptyErr".equals(ret)) { req.setAttribute("emptyErr", new Object()); req.getRequestDispatcher("/login.jsp").forward(req, resp); } else if("passEmptyErr".equals(ret)) { req.setAttribute("passEmptyErr", new Object()); req.getRequestDispatcher("/login.jsp").forward(req, resp); } else if("codeEmptyErr".equals(ret)) { req.setAttribute("codeEmptyErr", new Object()); req.getRequestDispatcher("/login.jsp").forward(req, resp); } else if("codeErr".equals(ret)) { req.setAttribute("codeErr", new Object()); req.getRequestDispatcher("/login.jsp").forward(req, resp); } else if("admin".equals(ret)) { req.getRequestDispatcher("/admin?flag=login").forward(req, resp); } else if("user".equals(ret)) { //req.getRequestDispatcher("/user").forward(req, resp); req.getRequestDispatcher("/user.jsp").forward(req, resp); } else if("passwordErr".equals(ret)) { req.setAttribute("passwordErr", new Object()); req.getRequestDispatcher("/login.jsp").forward(req, resp); } else { req.setAttribute("userNotExits", username); req.getRequestDispatcher("/login.jsp").forward(req, resp); } } }