我需要连续运行两个命令,从同一个流中读取数据.
var spawn = require('child_process').spawn;
var fs = require('fs');
var request = require('request');
var inputStream = request('http://placehold.it/640x360');
var identify = spawn('identify',['-']);
inputStream.pipe(identify.stdin);
var chunks = [];
identify.stdout.on('data',function(chunk) {
chunks.push(chunk);
});
identify.stdout.on('end',function() {
var size = getSize(Buffer.concat(chunks)); //width
var convert = spawn('convert',['-','-scale',size * 0.5,'png:-']);
inputStream.pipe(convert.stdin);
convert.stdout.pipe(fs.createWriteStream('half.png'));
});
function getSize(buffer){
return parseInt(buffer.toString().split(' ')[2].split('x')[0]);
}
Request人对此抱怨
Error: You cannot pipe after data has been emitted from the response.
当然,将inputStream改为fs.createWriteStream
也会产生同样的问题.
有没有一种方法可以在可读流完成管道后重用它?