具体代码如下所示：

var request=require("request");
var fs=require("fs");
function download1(url,filename,fn){
request(url).pipe(fs.createWriteStream(filename).on("close",function(err,res){
if(err){
console.log(err);
}else{
fn&&fn();
}
}))
}
function download2(url,filename,fn){
request.get({uri:url, encoding:'binary'},function(err,res){
if(!err){
fs.writeFile(filename,res.body,"binary",function(err,res){
if(!err){
fn&&fn();
}else{
console.log(err);
}
})
}
})
}

ps：下面看下nodejs 下载远程图片的实现代码，具体代码如下所示：

var express = require('express');
var request = require('request');
var http = require('http');
var url = require('url');
var fs = require("fs");
var router = express.Router();
/* GET home page. */
router.get('/', function (req, res, next) {
 var url = "http://www.valu.cn/images/1.gif";
 //request('http://www.valu.cn/images/1.gif').pipe(fs.createWriteStream('./public/upload/downImg/logonew.png'));
 var req = http.get(url, function (res) {
 var imgData = "";
 res.setEncoding("binary"); //一定要设置response的编码为binary否则会下载下来的图片打不开
 res.on("data", function (chunk) {
 imgData += chunk;
 });
 res.on("end", function () {
 fs.writeFile("./public/upload/downImg/logonew.png", imgData, "binary", function (err) {
 if (err) {
 console.log("保存失败");
 }
 console.log("保存成功");
 });
 });
 res.on("error", function (err) {
 console.log("请求失败");
 });
 });
 req.on('error', function (err) {
 console.log("请求失败2" + err.message);
 });
 res.render('index', {title: '首页2'});
});
module.exports = router;