Node.js stream.Writable 关闭事件
stream.Writable 关闭事件是 Stream 模块的内置应用程序编程接口,用于在关闭流及其任何隐藏资源(例如,文件描述符)时发出。此事件意味着不会发出更多事件,并且不会发生进一步的计算。
句法:
Event: 'close'
返回值:如果在此事件之后调用 writable.destroy() 方法或关闭文件描述符,则发出此事件,否则不发出。
下面的例子说明了 Node.js 中stream.Writable close 事件的使用:
示例 1:
// Node.js program to demonstrate the
// close event
// Including stream module
const stream = require('stream');
// Creating a stream and creating
// a write function
const writable = new stream.Writable({
// Write function with its
// parameters
write: function(chunk, encoding, next) {
// Converting the chunk of
// data to string
console.log(chunk.toString());
next();
}
});
// Writing data
writable.write('GeeksforGeeks');
// Emitting close event
writable.on('close', () => {
console.log("No further operations will be performed!");
});
// Calling destroy function
writable.destroy();
// Shows that the program ends
console.log("program is ended.");
输出:
GeeksforGeeks
program is ended.
No further operations will be performed!
在上面的示例中,在关闭事件之后调用 writable.destroy() 方法,因此它被发出。
示例 2:
// Node.js program to demonstrate the
// close event
// Including stream module
const stream = require('stream');
// Creating a stream and creating
// a write function
const writable = new stream.Writable({
// Write function with its
// parameters
write: function(chunk, encoding, next) {
// Converting the chunk of
// data to string
console.log(chunk.toString());
next();
}
});
// Writing data
writable.write('GeeksforGeeks');
// Emitting close event
writable.on('close', () => {
console.log("No further operations will be performed!");
});
// Shows that the program ends
console.log("program is ended.");
输出:
GeeksforGeeks
program is ended.
因此,此处未调用 writable.destroy()函数,因此未执行关闭事件。
参考: https://nodejs.org/api/stream.html#stream_event_close