angular2+nodejs实现图片上传

在使用angular2进行图片上传的时候，遇到了各种各样的问题。在多番尝试之后最终成功上传图片，下面将我的方法分享给大家：

nodejs 后台代码

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');
});

angular2前台代码

 //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));
   }