text: var createError = require('http-errors');
  var express = require('express');
  var path = require('path');
  var cookieParser = require('cookie-parser');
  var logger = require('morgan');
  
  var indexRouter = require('./routes/index');
  var usersRouter = require('./routes/users');
  
  var app = express();
  
  // 模板引擎
  app.engine('html', require('express-art-template'));
  app.set('view engine', 'html');
  
  // 中间键 解析post请求参数
  var bodyParser = require('body-parser')
  app.use(bodyParser.urlencoded({ extended: true }))
  
  app.use(logger('dev'));
  app.use(express.json());
  app.use(express.urlencoded({ extended: false }));
  app.use(cookieParser());
  // 托管静态资源
  app.use('/public', express.static('public'));
  app.use('/node_modules', express.static('node_modules'));
  
  // 路由容器
  app.use('/', indexRouter);
  app.use(usersRouter);
  
  // catch 404 and forward to error handler
  app.use(function (req, res, next) {
    next(createError(404));
  });
  
  // error handler
  app.use(function (err, req, res, next) {
    // set locals, only providing error in development
    res.locals.message = err.message;
    res.locals.error = req.app.get('env') === 'development' ? err : {};
  
    // render the error page
    res.status(err.status || 500);
    res.render('error');
  });
  
  module.exports = app;
  