上面一片文章已经介绍怎样创建nodejs服务端服务，这篇将express搭建路由第一章搭建nodejs服务

配置app.js引入相关中间件

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

//文件读取
var fs = require("fs");

//gzip压缩
var compression = require('compression');

//处理异常
var domain = require('domain');

var app = express();

设置模板引擎

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

使用相关中间件

// uncomment after placing your favicon in /public
app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
//log日志
app.use(logger('dev'));
//HTTP请求体解析中间
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: false
}));
//对http传入的cookie进行解析后赋值给req.cookies
app.use(cookieParser());
//引入public文件里面的静态资源包括css,js,image etc.
app.use(express.static(path.join(__dirname, 'public')));

引入路由文件

//路由文件读取
var file = fs.readdirSync('./routes');
for (var i in file) {
    var name = file[i].replace('.js', '');
    require('./routes/' + name)(app, domain);
}

抓取错误信息

// catch 404 and forward to error handler
app.use(function(req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});

错误处理，渲染404页面

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.statusCode = 404;
    res.render('htmlerror');
});

抛出模块

module.exports = app;

下一章express搭建前端项目3