express手工实现session原理

 1 var express = require('express');
 2 var cookieParser = require('cookie-parser');
 3 var bodyParser = require('body-parser');
 4 var app = express();
 5 app.use(bodyParser.json());
 6 app.use(bodyParser.urlencoded({ extended: false }));
 7 app.use(cookieParser())
 8 
 9 
10 var sessions = {  };
11 var key = ' session_id ';
12 var EXPIRES = 20 * 60 * 1000;
13 var generate = function(){
14   var session = {};
15   session.id = (new Date().getTime() + Math.random());
16   session.cookie = {
17     expire : new Date().getTime() + EXPIRES
18   }
19   sessions[session.id] = session;
20   return session;
21 }
22 
23 
24 app.use("/",function(req, res,next){
25 
26   var id = req.cookies.id;
27   if(!id){
28     console.log("无ID");
29     req.session = generate();
30     console.log(req.session);
31   }else{
32     console.log("有ID");
33     var session = sessions[id];
34       if(session){
35         console.log("有session");
36         req.session = session;
37       }else{
38         req.session = generate();
39       }
40   }
41   res.setHeader('Set-Cookie',['id='+req.session.id,'aaa="bbbb"','path=/', 'max-age=360000','expires='+req.session.cookie.expire]);
42   next()
43 
44 });
45 app.get("/",function(req,res){
46   if(!req.session.isvist){
47     req.session.isvist = true;
48     res.send("第一次登陆")
49   }else{
50     console.log(sessions)
51     res.send("再次登陆")
52   }
53 })
54 
55 app.listen(8080);

修正后：将app.use(“/”)改为app.use("*")

var express = require('express');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var app = express();
var user = require('./modules/user');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(cookieParser());

console.log(user);
var sessions = {  };
var key = ' session_id ';
var EXPIRES = 20 * 60 * 1000;
var generate = function(){
  var session = {};
  session.id = (new Date().getTime() + Math.random());
  session.cookie = {
    expire : new Date().getTime() + EXPIRES
  }
  sessions[session.id] = session;
  return session;
}

//通过中间件实现在每一个路由中都生成session
app.use("*",function(req, res,next){
  req.aa = "aaaaa";
  var id = req.cookies.id;
  if(!id){
    console.log("无ID");
    req.session = generate();
    console.log(req.session);
  }else{
    console.log("有ID");
    var session = sessions[id];
      if(session){
        console.log("有session");
        req.session = session;
      }else{
        req.session = generate();
      }
  }
  res.setHeader('Set-Cookie',['id='+req.session.id,'aaa="bbbb"','path=/', 'max-age=360000','expires='+req.session.cookie.expire]);
  next()

});
app.get("/",function(req,res){
  if(!req.session.isvist){
    req.session.isvist = true;
    res.send("第一次登陆")
  }else{
    console.log(sessions)
    res.send("再次登陆")
  }
})
app.get('/a',function(req,res){

})

app.listen(8080);

基本逻辑就是，用户进入路由先判断cookie中有没有ID；

没有Id的话生成一个新的session；

有ID的话根据ID去内存或数据库查找session

若没有session生成一个新的session；

若有session查看其过期时间，若过期生成新的session

若没有过期，更新其时间；

最后将session赋值给req.session；

这样在其他路由里就可以访问session了，并且req.session可以挂载任何属性，比方说用户登录后将用户信息挂载到req.session上

坚持下去就能成功