Node.js Stream(stream)

Learning points:

Read data from the stream

Write to the stream

Pipe stream

Chain stream

Node.js Stream(Stream)

Read data from the stream

Case: main.js

[code]var fs = require('fs');
var data = '';
// 创建可读流
var readerStream = fs.createReadStream('input.txt');
// 设置utf8编码
readerStream.setEncoding('UTF8');
// 处理流事件
// data 当有数据可读时触发
readerStream.on('data', function (chunk) {
    data += chunk;
});
// end 当没有数据读时触发
readerStream.on('end', function () {
    console.log(data);
});
// error  在接收和写入过程中发生错误时触发。
readerStream.on('error', function (err) {
    console.log(err.stack);
});
console.log('程序执行完毕。');

##Write to the stream

Case: main2.js

[code]var fs = require('fs');
var data = '我是谁？';
// 创建写入流
var writeStream = fs.createWriteStream('ouput.txt');
// 编码
writeStream.write(data, 'UTF8');
// 标记文件末尾
writeStream.end();
// 处理流事件
// finish 所有数据已被写入到底层系统时触发。
writeStream.on('finish', function () {
    console.log('写入完成');
});
// error 在读入和写入数据是触发
writeStream.on('error', function (err) {
    console.log(err.stack);
});
console.log('程序执行完毕。');

Pipeline flow

Input data from one stream into another stream

Case: pipe.js

[code]var fs = require('fs');
// 创建可读流
var readerStream = fs.createReadStream('input.txt');
// 创建写入流
var writeStream = fs.createWriteStream('ouput.txt');
// 管道读写
readerStream.pipe(writeStream);
console.log('程序执行完毕。');

Chain flow

is to connect multiple input and output streams

Case: compression File express.js

[code]var fs = require('fs');
var zlib = require('zlib');
// 将 input.txt 压缩为 input.gz
fs.createReadStream('input.txt')
    .pipe(zlib.createGzip())
    .pipe(fs.createWriteStream('input.gz'));
console.log('文件压缩完毕');

Case: Decompress the file decompress.js

[code]var fs = require('fs');
var zlib = require('zlib');
// 解压 input.gz 为 input.gz.txt
fs.createReadStream('input.gz')
    .pipe(zlib.createGunzip())
    .pipe(fs.createWriteStream('input.gz.txt'));
console.log('解压文件完毕');

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