node-express自动构建项目详解

app.js文件 搭建后自动生成的入口文件

 

var createError = require('http-errors');

var express = require('express');

var path = require('path');

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

//cookie解析者解析cookie数据

//引入带有cookie-parser这种叫做中间件

//express中间件（当获取数据时对相应的数据流做预处理 ）

 

var logger = require('morgan');

//logger代表着后台输出的一些数据

//下面的路由可以提取出去写在js文件中格式如下：

//var express = require('express');

//var router = express.Router();

//router.get('/', function(req, res, next) {

//res.render('index', { title: 'Express' });

//})

//module.exports = router;

var indexRouter = require('./routes/index');

var usersRouter = require('./routes/users');

 

var app = express();

 

// view engine setup

//设置文件默认的路径

app.set('views', path.join(__dirname, 'views'));

app.set('view engine', 'ejs');//设置模板引擎ejs

 

app.use(logger('dev'));

app.use(express.json());

app.use(express.urlencoded({ extended: false }));

//use方法加载中间件

//post 把数据放在 body get把数据放在协议里

app.use(cookieParser());

app.use(express.static(path.join(__dirname, 'public')));

 

app.use('/', indexRouter);

app.use('/users', 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;