如何使用 Node.js createReadStream 和 createWriteStream 写入多个文件

Question

好的，这就是这段代码的总体目标。我正在使用 TinyPNG 的 API 来压缩 png 文件的文件夹。我有一个输入文件夹，其中包含许多名为 filename.png 的文件。此代码将文件名目录读取到数组文件中，然后为这些文件创建读取和写入流，以发送到 API、处理并返回，以便将其写入输出文件夹中的文件。我知道该代码适用于一个文件，但除此之外还会引发 write after end 异常，因为管道在第一个文件之后自动关闭。我尝试将输入和输出设置为数组，但这只会引发另一个异常。

任何关于如何设置多个读取和写入流的提示都非常棒，对每个人都非常有用:)。

当前代码：

var fs = require('fs');
var inputFolder = "input/";
var outputFolder = "output/";
var https = require("https");

var key = "GETYOUROWNFREEONEFROMTINYPNG.ORG";

process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";

var options = require("url").parse("https://api.tinypng.com/shrink");
options.auth = "api:" + key;
options.method = "POST";

console.log("Reading files...");

fs.readdir("./input", function (err, files) {

  if (err) throw err;

  console.log(files.length + " files read...");

  var input;
  var output;
  var request;

      for(var i = 0; i < files.length; i++)
      {
        input = fs.createReadStream(inputFolder + files[i]);
        output = fs.createWriteStream(outputFolder + files[i]);

          request = new https.request(options, function(response) {
            if (response.statusCode === 201) {
              /* Compression was successful, retrieve output from Location header. */
              https.get(response.headers.location, function(response) {
                response.pipe(output);
              });
            } else {
              /* Something went wrong! You can parse the JSON body for details. */
              console.log("Compression failed");
            }
          });

          input.pipe(request);
      }

});

感谢@Wyatt提供的答案，这是供其他人使用的固定文件：

var fs = require('fs');
var inputFolder = "input/";
var outputFolder = "output/";
var https = require("https");

var key = "WotZ46HnxPl_HwpT3uZjtY_0f8fMEiSR";

process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";

var options = require("url").parse("https://api.tinypng.com/shrink");
options.auth = "api:" + key;
options.method = "POST";

console.log("Reading files...");

fs.readdir("./input", function (err, files) {

  if (err) throw err;

  console.log(files.length + " files read...");

  var input, request;

  for(var i = 0; i < files.length; i++){
    input = fs.createReadStream(inputFolder + files[i]);
    request = closureRequest(fs.createWriteStream(outputFolder + files[i]));
    input.pipe(request);
  }

});


function closureRequest(output){
    return new https.request(options, function(response) {
        if (response.statusCode === 201) {
          /* Compression was successful, retrieve output from Location header. */
          https.get(response.headers.location, function(response) {
            response.pipe(output);
          });
        } else {
          /* Something went wrong! You can parse the JSON body for details. */
          console.log("Compression failed");
        }
    });
} 

Answer 1

您在循环中反复重新分配输出变量，而请求回调试图引用它。您可以捕获闭包中的每个值来解决此问题。

...

function closureRequest(output){
    return new https.request(options, function(response) {
        if (response.statusCode === 201) {
          /* Compression was successful, retrieve output from Location header. */
          https.get(response.headers.location, function(response) {
            response.pipe(output);
          });
        } else {
          /* Something went wrong! You can parse the JSON body for details. */
          console.log("Compression failed");
        }
    });
}

var input
  , request
  ;

for(var i = 0; i < files.length; i++){
    input = fs.createReadStream(inputFolder + files[i]);
    request = closureRequest(fs.createWriteStream(outputFolder + files[i]));
    input.pipe(request);
 }