Node.js基础代码示例，带注释

'use strict';var http = require('http');//端口号var port = process.env.PORT || 1337;/** * 回调函数的使用 *///回调函数var fs = require("fs");//回调函数fs.readFile('./input.txt', function (err, data) {    if (err) return console.error(err);    console.log(data.toString());});/************end**************//** * 事件驱动程序 *///引入events模块var events = require('events');//创建eventEmitter对象var eventEmitter = new events.EventEmitter();//创建时间处理程序var connectHandler = function conneted() {    console.log("connect success.");    //触发 data_received 事件    eventEmitter.emit('data_received');}//绑定connection 事件处理程序eventEmitter.on('connection', connectHandler);//使用匿名函数绑定data_received事件eventEmitter.on('data_received', function () {    console.log('received data1 success.');});eventEmitter.on('data_received', function () {    console.log('received data2 success.');});//触发connection事件setTimeout(function () {    eventEmitter.emit('connection');}, 1000);console.log('program run over.');/************end**************//************Buffer对象************/var buf = Buffer.alloc(26);for (var i = 0; i < 26; i++) {    buf[i] = i + 97;}console.log(buf.toString('ascii'));// 输出: abcdefghijklmnopqrstuvwxyzconsole.log(buf.toString('ascii', 0, 5)); // 输出: abcdeconsole.log(buf.toString('utf8', 0, 5));    // 输出: abcdeconsole.log(buf.toString(undefined, 0, 5)); // 使用 'utf8' 编码, 并输出: abcde//buffer转Jsonvar buffer2json = Buffer.from('aabbc!');var _json = buffer2json.toJSON(buffer2json);console.log("The Buffer2Json is " + _json);//缓冲区合并var buffer1 = Buffer.from('Me');var buffer2 = Buffer.from(' QinShiHuang');var buffer3 = Buffer.from(' DaQian');var buffer4 = Buffer.concat([buffer1, buffer2, buffer3]);console.log("The concat result is " + buffer4.toString());//缓冲区比较//返回一个数字，表示 buf 在 otherBuffer 之前，之后或相同。var cBuffer1 = Buffer.from('ABC');var cBuffer2 = Buffer.from('ABCD');console.log("The compare result is ")var compareResult = cBuffer1.compare(cBuffer2);if (compareResult < 0) {    console.log(cBuffer1 + ' at before of ' + cBuffer2);} else if (compareResult == 0) {    console.log(cBuffer1 + ' at after of ' + cBuffer2);} else {    console.log(cBuffer1 + ' is equal of ' + cBuffer2);}//拷贝缓冲区var copyBuffer1 = Buffer.from('I Hate You!');var copyBuffer2 = Buffer.from('Love');//将 buf2 插入到 buf1 指定位置上copyBuffer2.copy(copyBuffer1, 2);console.log("The copy content is " + copyBuffer1.toString());//缓冲区裁剪var sliceBuffer1 = Buffer.from('you are');var sliceBuffer2 = sliceBuffer1.slice(0, 3);console.log("sliceBuffer2 content : " + sliceBuffer2.toString());/************end**************//*******************Stream流start**********************/var streamData = '';//创建可读流var readerStream = fs.createReadStream('./input.txt');//设置编码为utf-8readerStream.setEncoding('UTF8');//处理流事件-->data,end,and errorreaderStream.on('data', function (chunk) {    streamData += chunk;});readerStream.on('end', function () {    console.log(streamData);});readerStream.on('error', function (err) {    console.log(err.stack);});console.log('stream run over!');//写入流var writeData = 'this is a very good thing,dont worry';// 创建一个可以写入的流，写入到文件 output.txt 中var writeStream = fs.createWriteStream('./output.txt');// 使用 utf8 编码写入数据writeStream.write(writeData, 'UTF8');// 标记文件末尾writeStream.end();// 处理流事件 --> finish, and errorwriteStream.on('finish', function () {    console.log('Write success.');});writeStream.on('error', function (err) {    console.log(err.stack);});//管道流//读取一个文件并写入另一个文件//创建一个可读流var rStream = fs.createReadStream('./input.txt');//创建一个可写流var wStream = fs.createWriteStream('./output1.txt');//管道读写操作//读取input.txt的文件内容，并将内容写入output.txt文件中rStream.pipe(wStream);console.log("Read and Write Over!");//链式流//压缩文件var zlib = require('zlib');//压缩input.txt文件为input.txt.gzfs.createReadStream('./input.txt')    .pipe(zlib.createGzip())    .pipe(fs.createWriteStream('./input.txt.gz'));console.log('zip complete!');//解压文件//fs.createReadStream('./input.txt.gz')//    .pipe(zlib.createGunzip())//    .pipe(fs.createWriteStream('./zip_input.txt'));//console.log('zipGun complete!');/*******************Stream流end**********************//*******************模块系统创建对象start**********************/var Hello = require('./hello');var hello = new Hello();hello.setName('Wang Da Niang');hello.sayHello();/*******************模块系统创建对象end**********************//*******************Node.js函数start**********************///一个函数可以作为另一个函数的参数function say(word) {    console.log(word);}function execute(someFunction, value) {    someFunction(value);}execute(say, 'WoZhenDeAiNi!');//匿名函数,方法隐藏在参数中execute(function (word) { console.log('NiMing:' + word); }, 'BuXiangShuoHua')/*******************Node.js函数end**********************//*******************Node.js全局对象start **********************///输出全局变量_filename的值，__filename 表示当前正在执行的脚本的文件名。它将输出文件所在位置的绝对路径，且和命令行参数所指定的文件名不一定相同。 如果在模块中，返回的值是模块文件的路径。console.log(__filename);// 输出全局变量 __dirname 的值，__dirname 表示当前执行脚本所在的目录。console.log(__dirname);//Process属性//输出到终端process.stdout.write("Hello World!\n")//通过参数读取process.argv.forEach(function (val, index, array) {    console.log(index + ':' + val);});//获取执行路径console.log(process.exePath);//平台信息console.log(process.platform);//Process方法//输出当前目录console.log('current direction is :' + process.cwd());//输出当前版本console.log('current version is :' + process.version);//输出内存使用情况console.log('current neicun is :'+process.memoryUsage());/*******************Node.js全局对象end**********************//************util.inherits继承方法start**************/var util = require('util');function Base() {    this.name = 'GuoJia';    this.base = 1995;    this.sayHello = function () {        console.log('Hello' + this.name);    };}Base.prototype.showName = function () {    console.log(this.name);}function Sub() {    this.name = 'Ai';}//使Sub继承于Baseutil.inherits(Sub, Base);var objBase = new Base();objBase.showName();objBase.sayHello();console.log(objBase);var objSub = new Sub();objBase.showName();//objSub.sayHello();console.log(objSub);/************util.inherits继承方法end**************//************util.inspect方法start**************///将任意对象转换 为字符串的方法，通常用于调试和错误输出function Person() {    this.name = 'LiXiuQi';    this.toString = function () {        return this.name;    };}var obj = new Person();console.log(util.inspect(obj));console.log(util.inspect(obj, true));/************util.inspect方法end**************//*******************启动服务start**********************/var url = require("url");var route = require('./route.js');function start(route) {    function onRequest(request, response) {        var pathname = url.parse(request.url).pathname;        console.log("Request for " + pathname + " received.");        //处理url地址参数        route(pathname);        // 发送 HTTP 头部         // HTTP 状态值: 200 : OK        // 内容类型: text/plain        response.writeHead(200, { 'Content-Type': 'text/plain' });        // 发送响应数据 "Hello World"        response.end('Hello World\n');    }    //创建服务    http.createServer(onRequest).listen(port);}start(route.route);/*******************启动服务end**********************/// 终端打印信息console.info("hi this is the first application!");