angular2和nodejs实现图片上传的的的功能

var express = require("express");
//网络请求模块
var request = require("request");
//引入nodejs文件系统模块
const fs = require('fs');
//引入body-parser
//包含在请求正文中提交的键/值对数据。 
//默认情况下，它是未定义的，并在使用body-parser中间件时填充。
var bodyParser = require('body-parser');
var app = express();
//解析 application/x-www-form-urlencoded，limit:'20mb'用于设置请求的大小
//解决nodejs Error: request entity too large问题
app.use(bodyParser.urlencoded({ limit:'20mb',extended: true })); 
//设置跨域访问
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");
 res.header("Content-Type", "application/json;charset=utf-8");
 next();
});
//上传图片
app.post('/upload',function(req,res){
 var imgData = req.body.url;
 var base64Data = imgData.replace(/^data:image\/\w+;base64,/, "");
 var dataBuffer = new Buffer(base64Data, 'base64');
 fs.writeFile("image.png", dataBuffer, function(err) {
 if(err){
 res.send(err);
 }else{
 res.send("保存成功！");
 }
 });
})

var server = app.listen(4444, function() {
 console.log('监听端口 4444');
});

 //上传图片
 /*
 * let data = {
 * size: '125422',
 * type: 'image/jpeg',
 * name: 'test.jpg',
 * url: base64
 * };
 *获取图片的base64码可以通过FileReader获取
 */

 uploadImage(data) {
 return new Promise((resolve, reject) => {
 let headers = new Headers({
 'Content-Type': 'application/x-www-form-urlencoded'
 });
 let options = new RequestOptions({
 headers: headers
 });
 this.http.post("http://localhost:4444/upload", this.toQueryString(data),options)
 .map(res => res.json())
 .subscribe(data => { resolve(data), error => { reject(error) } })
 })
 }


// JSON参数序列化
 private toQueryString(obj) {
 let result = [];
 for (let key in obj) {
 key = encodeURIComponent(key);
 let values = obj[key];
 if (values && values.constructor == Array) {
 let queryValues = [];
 for (let i = 0, len = values.length, value; i < len; i++) {
 value = values[i];
 queryValues.push(this.toQueryPair(key, value));
 }
 result = result.concat(queryValues);
 } else {
 result.push(this.toQueryPair(key, values));
 }
 }
 return result.join('&');
 }
 private toQueryPair(key, value) {
 if (typeof value == 'undefined') {
 return key;
 }
 return key + '=' + encodeURIComponent(value === null ? '' : String(value));
 }