express4.x中路由中间件和挂载路径的关系

express4.x 中一个路由中间件可以挂载到多个路由上，一个路由也可以绑定多个路由中间件，如:

//多个路由匹配一个路由中间件
app.use(['/gre+t', '/hel{2}o'], greet);

var greet = express.Router();

greet.get('/jp', function (req, res) {
  console.log(req.baseUrl); // /greet
  res.send('Konichiwa!');
});

app.use('/greet', greet);

//多个中间件匹配一个路由
app.use('/rtest', [r1, r2]);

var r1 = express.Router();
r1.get('/', function (req, res, next) {
  console.log("r1 router");
  next();
})

var r2 = express.Router();
r2.get('/', function (req, res, next) {
  console.log('r2 router ');
  res.send("r2 router " + req.app.get("view engine"))
  // next();
})