node.js http服務

Http是互聯網時代使用最廣泛的協議，沒有之一。

Node.js內置了http模塊，因此使用node.js搭建一個http服務非常簡單。

一、http實例

照舊，先來一個http的"Hello world！"，創建http.js文件，代碼如下：

//調用http模塊
var http = require('http');

var server = http.createServer();
server.on('request', function(request, response) {
    // 發送 HTTP 頭部
    // HTTP 狀態值: 200 : OK
    // 內容類型: text/plain
    response.writeHead(200, {'Content-Type': 'text/plain'});

    // 發送響應數據 "Hello World ！"
    response.end('Hello World !');
}).listen(8000);

console.log('Http server is started.');

運行http.js：

lee@mypc ~/works/nodejs/study4 $ node http.js 
Http server is started.

這時可以看到程序打印完"Http server is started"並沒有結束，而是一直佔據進程（監聽8000端口）。

然後我們另起一個terminal，用curl測試http服務：

lee@mypc ~/works/nodejs/study4 $ curl "http://localhost:8000"
Hello World !

成功打印出"Hello world !"

二、get請求

創建另一個文件http_get.js。

然後實現邏輯，接收到http請求後先判斷request.method，如果不是GET則返回404。如果是GET請求，則用url模塊獲取參數，並返回接收到的參數。

代碼如下：

//調用http模塊
var http = require('http');
//調用url模塊
var url = require('url');

var server = http.createServer();
server.on('request', function(request, response) {
    if(request.method == 'GET') {
        var params = url.parse(request.url, true).query;
        params = JSON.stringify(params);
        //服務端打印參數
        console.log('Get params:'+params);
        // 發送 HTTP 頭部
        // HTTP 狀態值: 200 : OK
        // 內容類型: text/plain
        response.writeHead(200, {'Content-Type': 'text/plain'});

        // 把請求參數返回給客戶端
        response.end(params+'\n');
    }
    else{
        response.writeHead(404, {'Content-Type': 'text/plain'});
        response.end('Not found !\n');
    }
}).listen(8000);

console.log('Http server is started.');

運行http_get.js:

lee@mypc ~/works/nodejs/study4 $ node http_get.js 
Http server is started.

用curl測試get得到正確結果:

lee@mypc ~/works/nodejs/study4 $ curl "http://localhost:8000?id=1&name=2"
{"id":"1","name":"2"}

測試post請求則得到"Not found":

lee@mypc ~/works/nodejs/study4 $ curl -d "" "http://localhost:8000"
Not found !

三、post請求
創建一個文件http_post.js。

然後實現邏輯，接收到http請求後先判斷request.method，如果不是POST則返回404。如果是POST請求，則獲取http body，並返回接收到的內容。

代碼如下：


//調用http模塊
var http = require('http');

var server = http.createServer();
server.on('request', function(request, response) {
    if(request.method == 'POST') {
        var data_post = '';
        request.on('data', function(data){
            data_post += data;
        });
        request.on('end', function(){
            //服務端打印參數
            console.log('Get body:'+data_post);
            // 發送 HTTP 頭部
            // HTTP 狀態值: 200 : OK
            // 內容類型: text/plain
            response.writeHead(200, {'Content-Type': 'text/plain'});

            // 把請求參數返回給客戶端
            response.end(data_post+'\n');
        })

    }
    else{
        response.writeHead(404, {'Content-Type': 'text/plain'});
        response.end('Not found !\n');
    }
}).listen(8000);

console.log('Http server is started.');

運行http_post.js:

lee@mypc ~/works/nodejs/study4 $ node http_post.js 
Http server is started.

用curl測試post得到正確結果:

lee@mypc ~/works/nodejs/study4 $ curl -d '{"username":"lee","id":1}' "http://localhost:8000"
{"username":"lee","id":1}

測試get請求則得到"Not found":

lee@mypc ~/works/nodejs/study4 $ curl "http://localhost:8000?id=1&name=2"
Not found !

Node.js提供了一個簡單的模塊系統，可以讓node.js的文件可以相互調用。模塊是node.js應用程序的基本組成部分，文件與模塊一一對應。也就是說一個文件就是一個模塊，這些文件可以是JavaScript、json或者編譯過的c/c++文件。

模塊調用

有一個模塊hello.js:

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;">exports<span class="token punctuation">.</span>sayhello <span class="token operator">=</span> <span class="token keyword" style="color: rgb(102, 217, 239);">function</span><span class="token punctuation">(</span>name<span class="token punctuation">)</span><span class="token punctuation">{</span>
    console<span class="token punctuation">.</span><span class="token function" style="color: rgb(230, 219, 116);">log</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'Hello, '</span><span class="token operator">+</span>name <span class="token operator">+</span><span class="token string" style="color: rgb(166, 226, 46);">'.'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span></code>

又有一個主模塊main.js:

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;"><span class="token keyword" style="color: rgb(102, 217, 239);">var</span> hello <span class="token operator">=</span> <span class="token function" style="color: rgb(230, 219, 116);">require</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'./hello'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

hello<span class="token punctuation">.</span><span class="token function" style="color: rgb(230, 219, 116);">sayhello</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'James'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code>

在以上代碼中，hello.js 通過 exports 對象把 sayhello 作爲模塊的訪問接口，在 main.js 中通過 require('./hello') 加載這個模塊，然後就可以直接訪問 hello.js 中 exports 對象的成員函數了。

運行效果如下：

<code class=" language-bash" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;">lee@mypc ~/works/nodejs/study5 $ node main.js
Hello, James.
</code>

另一種寫法，main2.js:

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;"><span class="token keyword" style="color: rgb(102, 217, 239);">var</span> sayhello <span class="token operator">=</span> <span class="token function" style="color: rgb(230, 219, 116);">require</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'./hello'</span><span class="token punctuation">)</span><span class="token punctuation">.</span>sayhello<span class="token punctuation">;</span>

<span class="token function" style="color: rgb(230, 219, 116);">sayhello</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'James'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code>

路徑

跟其它編程語言一樣，有相對路徑和絕對路徑

相對路徑之當前目錄:

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;"><span class="token keyword" style="color: rgb(102, 217, 239);">var</span> hello <span class="token operator">=</span> <span class="token function" style="color: rgb(230, 219, 116);">require</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'./hello'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code>

或

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;"><span class="token keyword" style="color: rgb(102, 217, 239);">var</span> hello <span class="token operator">=</span> <span class="token function" style="color: rgb(230, 219, 116);">require</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'./hello.js'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code>

相對路徑之上級目錄:

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;"><span class="token keyword" style="color: rgb(102, 217, 239);">var</span> hello <span class="token operator">=</span> <span class="token function" style="color: rgb(230, 219, 116);">require</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'../study5/hello'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code>

或

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;"><span class="token keyword" style="color: rgb(102, 217, 239);">var</span> hello <span class="token operator">=</span> <span class="token function" style="color: rgb(230, 219, 116);">require</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'../study5/hello.js'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code>

絕對路徑:

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;"><span class="token keyword" style="color: rgb(102, 217, 239);">var</span> hello <span class="token operator">=</span> <span class="token function" style="color: rgb(230, 219, 116);">require</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'/home/lee/works/nodejs/study5/hello'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code>

或

<code class=" language-javascript" style="padding: 0px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; direction: ltr; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; background-color: transparent;"><span class="token keyword" style="color: rgb(102, 217, 239);">var</span> hello <span class="token operator">=</span> <span class="token function" style="color: rgb(230, 219, 116);">require</span><span class="token punctuation">(</span><span class="token string" style="color: rgb(166, 226, 46);">'/home/lee/works/nodejs/study5/hello.js'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code>

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