Java Web Session 登录实例

 package cn.com.login;

 import java.io.IOException;
 import java.io.PrintWriter;
 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;


 public class Login extends HttpServlet {
     private static final long serialVersionUID = 1L;

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         response.setCharacterEncoding("UTF-8");
         response.setContentType("text/html;charset=UTF-8");

         String userName=request.getParameter("userName");
         String password=request.getParameter("password");
         PrintWriter out=response.getWriter();

         List list=Db.getAll();
         for(User user:list)
         {
             if(user.getUserName().equals(userName)&&user.getPassword().equals(password))
             {
                 request.getSession().setAttribute("user", user);
                 response.sendRedirect("/Session/index.jsp");
                 return ;
             }

         }
         out.write("用户名或者密码错误！");

     }

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         doGet(request,response);
     }

 }
 class Db
 {
     public static List list=new ArrayList();
     static
     {
         list.add(new User("aaa","123"));
         list.add(new User("bbb","123"));
         list.add(new User("ccc","123"));
     }
     public static List getAll()
     {
         return list;
     }
 }
 package cn.com.login;

 public class User {

     private String userName;
     private String password;

     public User() {
         super();
         // TODO Auto-generated constructor stub
     }
     public User(String userName, String password) {
         super();
         this.userName = userName;
         this.password = password;
     }
     public String getUserName() {
         return userName;
     }
     public void setUserName(String userName) {
         this.userName = userName;
     }
     public String getPassword() {
         return password;
     }
     public void setPassword(String password) {
         this.password = password;
     }


 }
 package cn.com.login;

 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 LogOut
  */
 public class LogOut extends HttpServlet {
     private static final long serialVersionUID = 1L;

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         HttpSession session=request.getSession(false);
         if(session==null)
         {
             response.sendRedirect("/Session/index.jsp");
             return ;
         }
         session.removeAttribute("user");
         response.sendRedirect("/Session/index.jsp");
     }


     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         doGet(request,response);
     }

 }



     Index.html

     "keywords" content="keyword1,keyword2,keyword3">
     "description" content="this is my page">
     "content-type" content="text/html; charset=UTF-8">







   "/Session/Login">

     用户名："text" name="userName"/>
     密码："password" name="password"/>
     "submit" value="登录" name="login"/>