node.js http服务

Http是互联网时代使用最广泛的协议，没有之一。

Node.js内置了http模块，因此使用node.js搭建一个http服务非常简单。

一、http实例

照旧，先来一个http的"Hello world！"，创建http.js文件，代码如下：

//调用http模块
var http = require('http');

var server = http.createServer();
server.on('request', function(request, response) {
    // 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 !');
}).listen(8000);

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

运行http.js：

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

这时可以看到程序打印完"Http server is started"并没有结束，而是一直占据进程（监听8000端口）。

然后我们另起一个terminal，用curl测试http服务：

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

成功打印出"Hello world !"

二、get请求

创建另一个文件http_get.js。

然后实现逻辑，接收到http请求后先判断request.method，如果不是GET则返回404。如果是GET请求，则用url模块获取参数，并返回接收到的参数。

代码如下：

//调用http模块
var http = require('http');
//调用url模块
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);
        //服务端打印参数
        console.log('Get params:'+params);
        // 发送 HTTP 头部
        // HTTP 状态值: 200 : OK
        // 内容类型: text/plain
        response.writeHead(200, {'Content-Type': 'text/plain'});

        // 把请求参数返回给客户端
        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.');

运行http_get.js:

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

用curl测试get得到正确结果:

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

测试post请求则得到"Not found":

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

三、post请求
创建一个文件http_post.js。

然后实现逻辑，接收到http请求后先判断request.method，如果不是POST则返回404。如果是POST请求，则获取http body，并返回接收到的内容。

代码如下：


//调用http模块
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(){
            //服务端打印参数
            console.log('Get body:'+data_post);
            // 发送 HTTP 头部
            // HTTP 状态值: 200 : OK
            // 内容类型: text/plain
            response.writeHead(200, {'Content-Type': 'text/plain'});

            // 把请求参数返回给客户端
            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.');

运行http_post.js:

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

用curl测试post得到正确结果:

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

测试get请求则得到"Not found":

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

Node.js提供了一个简单的模块系统，可以让node.js的文件可以相互调用。模块是node.js应用程序的基本组成部分，文件与模块一一对应。也就是说一个文件就是一个模块，这些文件可以是JavaScript、json或者编译过的c/c++文件。

模块调用

有一个模块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>

又有一个主模块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>

在以上代码中，hello.js 通过 exports 对象把 sayhello 作为模块的访问接口，在 main.js 中通过 require('./hello') 加载这个模块，然后就可以直接访问 hello.js 中 exports 对象的成员函数了。

运行效果如下：

<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>

另一种写法，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>

路径

跟其它编程语言一样，有相对路径和绝对路径

相对路径之当前目录:

<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>

相对路径之上级目录:

<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>

绝对路径:

<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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