new stream.Readable([options])
options
<Object>highWaterMark
<number> 在停止从底层资源读取之前存储在内部缓冲区中的最大字节数。 默认值:16384
(16KB) 或16
表示objectMode
流。encoding
<string> 如果指定,则缓冲区将使用指定的编码解码为字符串。 默认值:null
。objectMode
<boolean> 此流是否应表现为对象流。 这意味着stream.read(n)
返回单个值而不是大小为n
的Buffer
。 默认值:false
。emitClose
<boolean> 流被销毁后是否应该触发'close'
。 默认值:true
。read
<Function>stream._read()
方法的实现。destroy
<Function>stream._destroy()
方法的实现。autoDestroy
<boolean> 此流是否应在结束后自动调用自身的.destroy()
。 默认值:true
。
const { Readable } = require('stream');
class MyReadable extends Readable {
constructor(options) {
// 调用 stream.Readable(options) 构造函数。
super(options);
// ...
}
}
或者,当使用 ES6 之前的风格构造函数时:
const { Readable } = require('stream');
const util = require('util');
function MyReadable(options) {
if (!(this instanceof MyReadable))
return new MyReadable(options);
Readable.call(this, options);
}
util.inherits(MyReadable, Readable);
或者,使用简化的构造函数方法:
const { Readable } = require('stream');
const myReadable = new Readable({
read(size) {
// ...
}
});
options
<Object>highWaterMark
<number> The maximum number of bytes to store in the internal buffer before ceasing to read from the underlying resource. Default:16384
(16KB), or16
forobjectMode
streams.encoding
<string> If specified, then buffers will be decoded to strings using the specified encoding. Default:null
.objectMode
<boolean> Whether this stream should behave as a stream of objects. Meaning thatstream.read(n)
returns a single value instead of aBuffer
of sizen
. Default:false
.emitClose
<boolean> Whether or not the stream should emit'close'
after it has been destroyed. Default:true
.read
<Function> Implementation for thestream._read()
method.destroy
<Function> Implementation for thestream._destroy()
method.autoDestroy
<boolean> Whether this stream should automatically call.destroy()
on itself after ending. Default:true
.
const { Readable } = require('stream');
class MyReadable extends Readable {
constructor(options) {
// Calls the stream.Readable(options) constructor.
super(options);
// ...
}
}
Or, when using pre-ES6 style constructors:
const { Readable } = require('stream');
const util = require('util');
function MyReadable(options) {
if (!(this instanceof MyReadable))
return new MyReadable(options);
Readable.call(this, options);
}
util.inherits(MyReadable, Readable);
Or, using the simplified constructor approach:
const { Readable } = require('stream');
const myReadable = new Readable({
read(size) {
// ...
}
});