req.query

req.body

var session = require('express-session');
var cookieParser = require('cookie-parser');

app.use(cookieParser());
app.use(session({
  resave: true, // don't save session if unmodified
  saveUninitialized: false, // don't create session until something stored
  secret: 'admin', //密钥
  name: 'testapp', //这里的name值得是cookie的name，默认cookie的name是：connect.sid
  cookie: {
    maxAge: 80000
  } //设置maxAge是80000ms，即80s后session和相应的cookie失效过期
}));

app.use(function(req, res, next) {
  if (!req.session.user) {
    if (req.url == "/login") {
      next(); //如果请求的地址是登录则通过，进行下一个请求
    } else {
      res.redirect('/login');//跳转到登录页面
    }
  } else if (req.session.user) {
    next();//如果已经登录，则可以进入
  }
});

app.get('/login', function(req, res) {
  res.render("login");
});
app.post('/login', function(req, res) {
  if (req.body) {//判断时候有传值
    var user = {
      'username': req.body.username//获取用户名并赋值，这里之前可以自己做判断
    };
    req.session.user = user;//赋值session，自动跳转页面
    res.redirect('/admin');
  } else {
    res.redirect('/login');
  }
});
app.get('/logout', function(req, res) {//做的登出页面
  req.session.user = null;
  res.redirect('/login');
});