我正在尝试实现可读流的._read函数,当调用._read并且没有数据时会发生问题,文档说我可以推送(”)直到有更多数据出现,我应该只返回当流将永远不会有更多数据时为false. https://nodejs.org
https://nodejs.org/api/stream.html#stream_readable_read_size_1
但它也说,如果我需要这样做,那么我的设计就会出现严重问题.
https://nodejs.org/api/stream.html#stream_stream_push
但我无法找到替代方案.
码:
var http = require('http'); var https = require('https'); var Readable = require('stream').Readable; var router = require('express').Router(); var buffer = []; router.post('/', function(clientRequest, clientResponse) { var delayedMSStream = new Readable; delayedMSStream._read = function() { var a=buffer.shift(); if(typeof a === 'undefined'){ this.push(''); return true; } else { this.push(a); if(a===null) { return false; } return true; } }; //I need to get a url from example.com https.request({hostname:'example.com'}, function(exampleResponse){ data=''; exampleResponse.on('data',function(chunk){data+=chunk}); exampleResponse.on('end',function(){ var MSRequestOptions = {hostname: data, method: 'POST'}; var MSRequest = https.request(MSRequestOptions, function(MSResponse){ MSResponse.on('end', function () { console.log("MSResponse.on(end)");//>>> });//end MSResponse.on(end) }); //end MSRequest delayedMSStream.pipe(MSRequest); }); }); clientRequest.on('data', function (chunk) { buffer.push(chunk); }); clientRequest.on('end', function () {//when done streaming audio buffer.push(null); }); });//end router.post('/')
说明:
客户端向我的服务器发送POST请求流音频,我的服务器从example.com请求一个URL,当example.com用url响应时,我的服务器将音频流传输给它.
什么是更聪明的方法呢?
因此,如果我正确地执行代码,您:>收到请求,
>向远程端点发出您自己的请求并获取URL
>对该URL发出新请求并将其传递给原始响应.
有其他方法可以做到这一点,如果你只是改善命名,甚至你的方式对我来说会更清洁.此外,将大量请求拆分为一些具有较小责任范围的函数可能会有所帮助.
我会这样做端点:
let http = require('http'); let https = require('https'); let Readable = require('stream').Readable; let router = require('express').Router(); let buffer = []; /** * Gets some data from a remote host. Calls back when done. * We cannot pipe this directly into your stream chain as we need the complete data to get the end result. */ function getHostname(cb) { https.request({ hostname: 'example.com' }, function(response) { let data = ''; response.on('error', err => cb(err)); // shortened for brewity response.on('data', function(chunk) { data = data + chunk; }); response.on('end', function() { // we're done here. cb(null, data.toString()); }); }); } router.post('/', function(request, response) { // first let's get that url. getHostname(function(err, hostname) { if (err) { return response.status(500).end(); } // now make that other request which we can stream. https.request({ hostname: hostname, method: 'POST' }, function(dataStream) { dataStream.pipe(response); }); }); });
现在,正如评论中所说,使用streams2,您不必管理您的流.对于0.10之前的节点版本,您必须收听“读取”,“数据”等事件,并使用较新的节点版本进行处理.此外,你甚至不需要它,溪流足够聪明,可以自己处理背压.