Easy to create Nodejs server (5): event handler _node.js

To make a different response to the difference, we introduce an event handler module.

The module is named Requesthandlers, and we add start () and upload () two placeholder functions.

The Requesthandlers.js code is as follows:

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function Start () {
Console.log (this is called when accessing/star.) ");
}

function upload () {
Console.log (this is called when accessing/upload.) ");
}

Exports.start = start;
Exports.upload = upload;

In real applications, the number of request handlers will increase, and we certainly do not want to have a new URL or request handler every time, in order to complete the request in the route

To the mapping of the handler and toss it back and forth.

In addition, we don't want to have a lot of If Request = X then call handler y in the route, which makes the code look messy and unprofessional.

Here I will use the concept of associative arrays to handle this requirement, we pass a series of request handlers through an object, and we need to inject this object into the route () function in a loosely coupled way.

Let's first introduce this object into the main file index.js:

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var server = require ("./server");
var router = require ("./router");
var requesthandlers = require ("./requesthandlers");

var handle = {};
handle["/"] = Requesthandlers.start;
handle["/start"] = Requesthandlers.start;
handle["/upload"] = requesthandlers.upload;

Server.start (Router.route, handle);

For example, I would like to add a/show mapping, directly adding a sentence handle["/show"] requesthandlers.show;

Haha, so the code is not simple and more orderly?!

Next we pass the handle object to the server, server.js the following modifications:

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var http = require ("http");
var url = require ("url");
function start (route, handle) {
function onrequest (request, Response) {
var pathname = Url.parse (request.url). Pathname;
Console.log ("Request for" + Pathname + "received.");
Route (handle, pathname);
Response.writehead ({"Content-type": "Text/plain"});
Response.Write ("Hello World");
Response.End ();
}
Http.createserver (ONrequest). Listen (8888);
Console.log ("Server has started.");
}
Exports.start = start;

Modify the route () function in the Route.js file accordingly:

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function route (handle, pathname) {
Console.log ("About to route a request for" + pathname);
if (typeof handle[pathname] = = ' function ') {
Handle[pathname] ();
} else {
Console.log ("No request handler found for" + pathname);
}
}
Exports.route = route;

We will handle object as parameters to the server, and then by the route received, and finally by routing to determine the current path of the corresponding request handler exists, the existence of the call to the corresponding function.

We can get the request handler function from the passed object in the same way that we get the element from the associative array. So there is a concise and fluent form like handle[pathname] (), the expression, the feeling is as mentioned in the front: "Hey, please help me deal with this path."

In this way, we can make different processing according to different requests.

In the next section, we will further transform the code to allow the server to make some actual feedback operations.