• Nodejs in Visual Studio Code 02.学习Nodejs


    1.开始

    源码下载:https://github.com/sayar/NodeMVA

    在线视频:https://mva.microsoft.com/en-US/training-courses/using-node-js-with-visual-studio-code-13920

    2.事件驱动编程语言Nodejs

    阻塞与非阻塞(Blocking I/O and Non Blocking I/O)

    Blocking I/O

    var fs = require('fs');
    
    var contents = fs.readFileSync('package.json').toString();
    console.log(contents);

    Non Blocking I/O

    var fs = require('fs');
    
    fs.readFile('package.json', function (err, buf) {
         console.log(buf.toString());
    });

    Nodejs与C#相反,readFileSync表示阻塞线程,而readFile不阻塞线程异步执行方法,调用完成后执行callback方法。

    注:在c#中同步方法一般为object.action,同步方法会阻塞线程等待耗时操作执行完成,异步方法为object.actionAsyc,异步方法经常有个异步事件可以注册待异步方法执行结束后调用。

    3.Hello World

    打开源码文件夹01_HelloWorld,包含两个文件app.js和package.json

    app.js

    console.log('Hello world'); //在控制台中输出Hello World , 令人熟悉的console类
    

    package.json

    {
      "name": "_01_HelloWorld",
      "version": "0.0.0",
      "description": "Hello World",
      "main": "app.js",
      "author": {
        "name": "Rami Sayar",
        "email": ""
      }
    }
    

    打开CMD执行命令node app可以看到执行结果Hello World。

    $ cd 01_HelloWorld
    $ node app
    Hello World
    

      

    4.FileIO

    打开源码文件夹03_FILEIO

    app.js

    var fs = require('fs');
    
    //阻塞I/O toString 用起来很顺手,比学C#简单多了
    var contents = fs.readFileSync('package.json').toString();
    console.log(contents);
    
    //非阻塞I/O
    fs.readFile('package.json', function (err, buf) {
        console.log(buf.toString());
    });
    

      

    5.Streams

    打开源码文件夹06_Streams

    app.js

    var fs = require("fs");
    
    // Read File
    fs.createReadStream("package.json")
        // Write File
        .pipe(fs.createWriteStream("out-package.json"));

    6.HelloWorldHttp

    打开源码文件夹02_HelloWorldHttp

    app.js

    var http = require('http');
    
    //处理http请求,返回200ok hello world
    var server = http.createServer(function (request, response) {
        response.writeHead(200, { "Content-Type": "text/plain" });
        response.end("Hello World
    ");
    });
    
    //侦听7000端口
    server.listen(7000);
    

    7.HelloWorldTCP

    打开源码文件夹05_HelloWorldTCP

    server.js

    var net = require('net');
    
    // The handler argument is automatically set as a listener for the 'connection' event
    var server = net.createServer(function (socket) {
        console.log("Connection from " + socket.remoteAddress);
        socket.end("Hello World
    ");
    });
    
    server.listen(7000, "127.0.0.1");

    client.js

    var net = require('net');
    
    var client = new net.Socket();
    
    client.connect(7000, "127.0.0.1");
    
    client.on('data', function (data) {
        console.log('Data: ' + data);
        client.destroy();
    });
    
    // Add a 'close' event handler for the client socket
    client.on('close', function () {
        console.log('Connection closed');
    });
    

    打开两个CMD窗口,这两个窗口将会互相通讯。

    $ cd 05_HelloWorldTCP
    $ node server
    

      

    $ cd 05_HelloWorldTCP
    $ node client
    

    8.Requests

    打开源码文件夹10_Requests

    app.js

    var request = require("request");
     
    request("http://www.bing.com", function(error, response, body) {
      console.log(body);
    });
    

      

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  • 原文地址:https://www.cnblogs.com/mengkzhaoyun/p/5355186.html
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