Node.js | Router(路由)

簡介

我們要為路由提供請求的URL和其他需要的GET及POST參數，隨後路由需要根據這些資料來執行相應的程式。

因此，我們需要查看HTTP請求，從中提取出請求的URL以及GET/POST參數。這一功能應當屬於路由還是伺服器(甚至作為一個模組自身的功能)確實值得探討，但這裡暫定其為我們的HTTP伺服器的功能。

我們需要的所有資料都會包含在request對像中，該對像作為onRequest()回調函數的第一個參數傳遞。但是為了解析這些資料，我們需要額外的Node.JS模組，它們分別是url和querystring模組。

                   url.parse(string).query
                                           |
           url.parse(string).pathname      |
                       |                   |
                       |                   |
                     ------ -------------------
http://localhost:8888/start?foo=bar&hello=world
                                ---       -----
                                 |          |
                                 |          |
              querystring.parse(queryString)["foo"]    |
                                            |
                         querystring.parse(queryString)["hello"]

範例

index.js

var server = require("./server");
var router = require("./router");
 
server.start(router.route);

server.js

var http = require("http");
var url = require("url");
 
function start(route) {
  function onRequest(request, response) {
    var pathname = url.parse(request.url).pathname;
    console.log("Request for " + pathname + " received.");
 
    route(pathname);
 
    response.writeHead(200, {"Content-Type": "text/plain"});
    response.write("Hello World");
    response.end();
  }
 
  http.createServer(onRequest).listen(8888);
  console.log("Server has started.");
}
 
exports.start = start;

router.js

function route(pathname) {
  console.log("About to route a request for " + pathname);
}
 
exports.route = route;

執行

1 2	$ node index.js Server has started.

瀏覽localhost:888：

瀏覽結果如下：

Request for / received.
About to route a request for /

// 以下是robots.txt和favicon.ico的Request
Request for /robots.txt received.
About to route a request for /robots.txt
Request for /favicon.ico received.
About to route a request for /favicon.ico

補充

修改server.js將pathname和queryString取出並印出。

server.js

var http = require("http");
var url = require("url");
var querystring = require("querystring");
 
function start(route) {
  function onRequest(request, response) {
    var pathname = url.parse(request.url).pathname;
    console.log("Request for " + pathname + " received.");
 
    route(pathname);

    var queryString = url.parse(request.url).query;
    console.log("Request queryString: " + queryString);
    console.log("Request queryString abcd value: " + querystring.parse(queryString)["abcd"]);
    console.log("Request queryString efgh value: " + querystring.parse(queryString)["efgh"]);
 
    response.writeHead(200, {"Content-Type": "text/plain"});
    response.write("Hello World");
    response.end();
  }
 
  http.createServer(onRequest).listen(8888);
  console.log("Server has started.");
}
 
exports.start = start;

瀏覽http://localhost:8888/test?abcd=1234&efgh=5678：

瀏覽結果如下：

Request for /test received.
About to route a request for /test
Request queryString: abcd=1234&efgh=5678
Request queryString abcd value: 1234
Request queryString efgh value: 5678
Request for /favicon.ico received.
About to route a request for /favicon.ico
Request queryString: null
Request queryString abcd value: undefined
Request queryString edgh value: undefined