如何关闭可读流（结束之前）？

如何关闭一个可读流在 Node.js 中？

var input = fs.createReadStream('lines.txt');

input.on('data', function(data) {
   // after closing the stream, this will not
   // be called again

   if (gotFirstLine) {
      // close this stream and continue the
      // instructions from this if
      console.log("Closed.");
   }
});

这会比：

input.on('data', function(data) {
   if (isEnded) { return; }

   if (gotFirstLine) {
      isEnded = true;
      console.log("Closed.");
   }
});

但这不会停止阅读过程......

Edit:好消息！从 Node.js 8.0.0 开始readable.destroy正式可用：https://nodejs.org/api/stream.html#stream_read_destroy_error

ReadStream.destroy

您可以致电ReadStream.destroy随时发挥作用。

var fs = require("fs");

var readStream = fs.createReadStream("lines.txt");
readStream
    .on("data", function (chunk) {
        console.log(chunk);
        readStream.destroy();
    })
    .on("end", function () {
        // This may not been called since we are destroying the stream
        // the first time "data" event is received
        console.log("All the data in the file has been read");
    })
    .on("close", function (err) {
        console.log("Stream has been destroyed and file has been closed");
    });

公共职能ReadStream.destroy没有记录（Node.js v0.12.2），但你可以看看GitHub 上的源代码 (2012 年 10 月 5 日提交).

The destroy函数内部标记ReadStream实例被销毁并调用close函数来释放文件。

您可以收听关闭事件确切地知道文件何时关闭。这结束事件除非数据完全消耗，否则不会触发。

请注意，destroy（以及close) 函数特定于fs.ReadStream。没有通用的部分流.可读“界面”。