node. JS (vi) "Buffer" "Stream"

Net Buffer Stream

1  NewBuffer (' Hello Pikachu ')2 //<buffer 6c 6c 6f E7 9a ae e5 8d A1 e4 B8 98>3 4 NewBuffer (' Hello Pikachu ', ' base64 ')5 //<buffer 1d E9 A1 af>6 7 varBUF =NewBuffer (' 123456 '); Console.log (BUF)8 //undefined9 Ten varBUF =NewBuffer (7); Buf.write (' 12345678 '); Console.log (buf.length) One //7, the Out-of-section will be ignored. A  -  varBUF =NewBuffer ([1,2,3,4]); Console.log (BUF) - //<buffer 04>

Buffer for binary data processing
At the beginning of the length is specified, no matter how the fight, the length will not change

1 varFS = require (' FS ');2 3Fs.readfile (' Imooc_class.jpg ',function(Err, origin_buffer) {4 Console.log (Buffer.isbuffer (Origin_buffer));5 6Fs.writefile (' imooc_buffer.jpg ', Origin_buffer,function(err) {7         if(Err) console.log (err);8     });9 Ten     varBase64image = origin_buffer.tostring (' base64 ')); One Console.log (base64image); A  -     varDecodedImage =NewBuffer (Base64image, ' base64 '); - Console.log (Buffer.compare (Origin_buffer, DecodedImage)); the  -Fs.writefile (' logo_decoded.jpg ', DecodedImage,function(err) { -         if(Err) console.log (err); -     }); +});

Stream flow
/**********************************/

1 varHTTP = require (' http ');2 varFS = require (' FS ');3 varRequest = require (' request '));4 5Http.createserver (function(req, res) {6     /*fs.readfile (' imooc_class.jpg ', function (err, res) {7 if (err) {8 res.end (' File not exist! ');9 }else {Ten Res.writeheader ($, {' Content-type ': ' text/html '}); One res.end (data); A         } -     });*/ -  the     //fs.createreadstream (' imooc_class.jpg '). pipe (res); -  -     //Crawl page pictures, output to a specified port -Request ('http://imgsrc.baidu.com/forum/w +  -%3d580/sign=e2f3b45fa086c91708035231f93c70c6/fb781bd5ad6eddc426e3e45c3edbb6fd53663399.jpg '). pipe (res); +}). Listen (8090);

/********************************************/

1 var fs = require (' FS '); 2 3 fs.createreadstream (' 1.mp3 '). Pipe (Fs.createwritestream (' 1-pipe.mp3 '));

/********************************************/

1 varStream = require (' stream ');2 3 varreadable =Stream. readable;4 varwritable =Stream. writable;5 6 //instantiation of7 varReadstream =Newreadable ();8 varWritstream =Newwritable ();9 Ten //Readable stream OneReadstream.push (' I '); AReadstream.push (' Love ')); -Readstream.push (' node\n '); - //Readable stream End theReadstream.push (NULL); -  - //Writable Stream -Writstream._write =function(chunk, encode, CB) { + Console.log (chunk.tostring ()); - CB (); + }; A  atReadstream.pipe (Writstream);

/***************************************/

1 //Custom Flow2 varStream = require (' stream ');3 //Tool Class4 varUtil = require (' util '));5 6 functionReadstream () {7Stream. Readable.call ( This);8 }9 Ten util.inherits (Readstream, stream. readable); One  AReadstream.prototype._read =function () { -     //Readable stream -      This. push (' I '); the      This. push (' love '); -      This. push (' node\n '); -     //Readable stream End -      This. Push (NULL); + }; -  + functionWritstream () { AStream. Writable.call ( This); at      This. _cached =NewBuffer (' '); - } -  - util.inherits (Writstream, stream. writable); -  -Writstream.prototype._write =function(chunk, encode, CB) { in Console.log (chunk.tostring ()); - CB (); to }; +  - //Convert Stream the functionTransformstream () { *Stream. Transform.call ( This); $ }Panax Notoginseng  - util.inherits (Transformstream, stream. Transform); the  +Transformstream.prototype._transform =function(chunk, encode, CB) { A      This. push (chunk); the CB (); + }; -  $Transformstream.prototype._flush =function(CB) { $      This. Push (' Oh Yeah '); - }; -  the varrs =NewReadstream (); - varWS =NewWritstream ();Wuyi varTS =NewTransformstream (); the  -Rs.pipe (TS). pipe (WS);

node. JS (vi) "Buffer" "Stream"