session会话

index.html

访问TestServlet




登录




注销用户

login.html

用户名：

密码：

package servlet;

import java.io.IOException;

import 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.HttpSession;
@WebServlet(“/TestServlet”)
public class TestServlet extends HttpServlet {

private static final long serialVersionUID = 1L;
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //判断用户是否登录，从session中获取用户登录标识user，若不为null表示已经登录，否则未登录
    request.setCharacterEncoding("UTF-8");
    //获取session对象
    HttpSession session=request.getSession();
    String name=(String)session.getAttribute("user");
    if(null!=name){
        //已登录
        System.out.println("已经登录，登录用户："+name+",可以访问！");
    }else {
        //未登录
        System.out.println("用户还未登录，禁止访问！");
    }
}

}

package servlet;

import java.io.IOException;

import 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.HttpSession;
@WebServlet(“/LoginServlet”)
public class LoginServlet extends HttpServlet {

private static final long serialVersionUID = 1L;
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //设置请求字符集
    request.setCharacterEncoding("UTF-8");
    String name=request.getParameter("loginName");
    String pwd=request.getParameter("loginPwd");
    //验证用户有效性
    if("admin".equals(name)&&"123".equals(pwd)||"张三".equals(name)&&"666".equals(pwd)){
        //登录成功
        //在session中存储用户登录的标识
        HttpSession session=request.getSession();
        session.setAttribute("user", name);
        //转发index页面
        request.getRequestDispatcher("index.html").forward(request, response);
    }else {
        //登录失败
        //转发login页面
        request.getRequestDispatcher("login.html").forward(request, response);

    }

}

}

package servlet;

import java.io.IOException;

import 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.HttpSession;
@WebServlet(“/LoginOutServlet”)
public class LoginOutServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //获取session对象，并将session销毁
    HttpSession session=request.getSession();
    session.invalidate();
    System.out.println("已经注销用户！");
    response.sendRedirect("index.html");
}

}