nodejs+express+multer搭建文件上传文件预览功能

var express = require('express');
var app = express();
app.get('/', function (req, res) {
	res.sendStatus(200)
})
//创建实例
var server = app.listen(8081, function () {
	var port = server.address().port
	console.log("应用实例，访问地址为 http://127.0.0.1:%s", port)
})

var fs = require('fs');//文件管理相关
var multer = require('multer');//nodejs中间件，用于处理上传文件
// 创建 multer 实例并设置存储引擎
const storage = multer.diskStorage({
	destination: function (req, file, cb) {
		// 指定文件上传的目录
		cb(null, 'uploads/');
	},
	filename: function (req, file, cb) {
		cb(null, file.originalname);
	}
});
/*设置过滤器,可以上传哪类文件*/
const fileFilter = (req, file, cb) => {
	if (file.mimetype === 'image/jpeg' || file.mimetype === 'image/png') {
		cb(null, true);
	} else {
		cb(null, false);
	}
}
const upload = multer({ storage: storage, fileFilter: fileFilter });

// 单个文件上传
app.post('/upload', upload.single('file'), (req, res) => {
	console.log(req.file)
	if (req.file) {
		let file = req.file;
		let date = Date.now();
		// 重命名文件
		fs.renameSync('./uploads/' + file.filename, './uploads/' + date + file.originalname);
		res.json({code:200, msg: '上传成功', imgUrl: 'http://127.0.0.1:8081' + '/uploads/' + date + file.originalname })
	}
	else {
		res.json({code:401,msg:'上传失败,请上传正确格式的图片', data: null})
	}
});

//设置访问静态文件目录
app.use('/uploads', express.static('uploads'));

//跨越设置
app.use(cors());
app.all('*',function(req,res,next){
	res.header("Access-Control-Allow-Origin", "*");
	res.header("Access-Control-Allow-Headers", "X-Requested-With");
	res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
	next()
});