将多个文件通过管道传输到单个流 [英] pipe multipe files to a single stream

问题描述

所以我有一个文件名数组.

so i have an array of filenames.

我需要遍历每一个，将其作为一个流读取，一个接一个地通过管道传输到最后一个流.

I need to go through each of those, read it as a stream, pipe one by one to a final stream.

错误地，代码看起来像这样:

Erroneously, the code would look something like this:

var files = ['file1.txt', 'file2.txt', 'file3.txt'];
var finalStream = fs.createReadStream()//throws(i need a file path here)
(function pipeSingleFile(file){
    var stream = fs.createReadStream(file);
    stream.on('end', function(){
      if(files.length > 0){
        pipeSingleFile( files.shift() );
      }
    });
    stream.pipe(finalStream);
})( files.shift() )

finalStream.pipe(someOtherStream);
finalStream.on('end', function(){
  //all the contents were piped to outside
});

有没有办法做到这一点?

Is there anyway to achieve this?

推荐答案

我没有测试您提出的递归解决方案，但它可能不起作用，因为您正在修改原始 files 数组(在每次迭代中调用 files.shift()) 两次:在将其传递给您的函数时以及在函数内部时.这是我的建议:

I didn't test the recursive solution you proposed, but it may not work since you're modifying the original files array (calling files.shift()) two times on each iteration: when passing it to your function and also inside. Here's my suggestion:

var files = ['file1.txt', 'file2.txt', 'file3.txt'];

var writableStream = fs.createWriteStream('output.txt');

function pipeNext (files, destination) {
    if (files.length === 0) {
        destination.end();

        console.log('Done!');
    } else {
        var file = files.shift();
        var origin = fs.createReadStream(file);

        origin.once('end', function () {
            pipeNext(files, destination);
        });
        origin.pipe(destination, { end: false });

        console.log('piping file ' + file);
    }
}

pipeNext(files, writableStream);

我在文件上使用了 Writable 流作为示例，但您可以使用任何您想要的.您可以将此逻辑包装到另一个函数中，并将您的 Writable 流传递给它.

I used a Writable stream on a file just as an example, but you could use whatever you want. You can wrap this logic into another function and pass your Writable stream to it.

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