express随记01

系统变量的设置

• app.get(env) | process.env.NODE_ENV: 会自动判断当前环境类型;
• app.get(port) | process.env.PORT: 必须手动设置;

app.param([name], callback)

• 用来处理多个匹配

app.param('id', function (req, res, next, id) {
  console.log('CALLED ONLY ONCE');
  next();
})

app.get('/user/:id', function (req, res, next) {
  console.log('although this matches');
  next();
});

app.get('/user/:id', function (req, res) {
  console.log('and this matches too');
  res.end();
});

cookie

• 其默认值: { path: '/', httpOnly: true, secure: false, maxAge: null }

//注意获取和设置的不同

app.get('/', function (req, res) {
   if (!req.cookies.counter)
    res.cookie('counter', 0);
  else
    res.cookie('counter', parseInt(req.cookies.counter,10) + 1);
  res.status(200).send('cookies are: ', req.cookies);
})

• 签名加密的cookie

//会自动加密解密处理

app.use(cookieParser('test-sign'));
.........
app.get('/', function (req, res) {
  if (!req.signedCookies.counter)
    res.cookie('counter', 0, {signed: true});
  else
    res.cookie('counter', parseInt(req.signedCookies.counter,10) + 1, {signed: true});
  res.status(200).send('cookies are: ', req.signedCookies);
})

session

//将session保存到redis中

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

app.use(cookieParser());
app.use(session({
  resave: true,                             //是否强制保存session。即使没有被修改;
  saveUninitialized: true,             //是否强制保存不是初始化的session;
  name: 'connect.sid',                 //默认浏览器cookie保存的名称;
  store: new RedisStore({
    host: 'localhost',
    port: 6379
  }),
  secret: '0FFD9D8D-78F1-4A30-9A4E-0940ADE81645',
  cookie: { path: '/', maxAge: 3600000 }   
}));


app.get('/', function(req, res){
  console.log('Session ID: ', req.sessionID)
  if (req.session.counter) {
    req.session.counter = req.session.counter +1;
  } else {
    req.session.counter = 1;
  }
  res.send('Counter: ' + req.session.counter)
});

• 其中要控制的实效包括:ttl:session字段保存在数据库的实效;maxAge:cookie字段的有效时间;

• 如果设置cookie secure: true,那其只会在https时session才会去判断cookie值;

• session默认是httpOnly:true

• 一般要将saveUninitialized 设为false,避免未对session修改也被保存下来;

• express-session自带debug模式，运行时设置DEBUG=express-session开启;

• 一般流程

//登陆
login: fetching->no-session-found->[set]->saveing->split response->set-cookie
         [redirect]-> fetching->session-found->touching->split response->touched
//重新打开
reopen: fetching->session-found->touching->touched
//退出
logout:  fetching->session-found->[set]->no-session->
             [redirect]->fetching->no-session-found

全局参数

//两种形式

app.locals = {};
res.locals = {};

特殊的输出

• 设置头部

app.get('/set-csv', function(req, res) {
  var body = 'title, tags
' +
    'Practical Node.js, node.js express.js
' +
    'Rapid Prototyping with JS, backbone.js node.js mongodb
' +
    'JavaScript: The Good Parts, javascript
'
  res.set({'Content-Type': 'text/csv',
    'Content-Length': body.length,
    'Set-Cookie': ['type=reader', 'language=javascript']});
  res.end(body);
});

• 设置响应码

res.status(200).end();
res.status(200).send();
res.status(200).json();

• 数据流输出文件

app.get('/stream2', function(req, res) {
  var stream = fs.createReadStream(largeImagePath);
  stream.on('data', function(data) {
    res.write(data);
  });
  stream.on('end', function() {
    res.end();
  });
});

app.get('/stream1', function(req, res) {
  var stream = fs.createReadStream(largeImagePath);
  stream.pipe(res);
});

服务器开关

var server = http.createServer(app);
var boot = function () {
  server.listen(app.get('port'), function(){
    console.info('Express server listening on port ' + app.get('port'));
}); };
var shutdown = function() {
  server.close();
};

if (require.main === module) {
  boot();
} else {
  console.info('Running app as a module');
  exports.boot = boot;
  exports.shutdown = shutdown;
  exports.port = app.get('port');
}