javascript Node.js 中的 URL 路由
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URL routing in Node.js
提问by Henrik Andersson
Homework done:
做的功课：
How do I get started with Node.js [closed]
Backstory: I wanted to try and write my own framework but I'm running into some troubles, most likely due to not understanding it fully.
背景故事：我想尝试编写自己的框架，但遇到了一些麻烦，很可能是因为没有完全理解它。
What I want to achieve is a syntax that looks like this:
我想要实现的是一个看起来像这样的语法：
var app = require('./app'); //this part is understood and it works in my current code.
app.get('/someUrl', function(){ //do stuff here });
app.post('/someOtherUrl', function(){ //do stuff here });
I know of the Express-framework that has this same syntax but reading their source code still eludes me.
我知道 Express 框架具有相同的语法，但我仍然无法阅读它们的源代码。
This might be a trivial task to achieve but I simply can't produce it, yet.
这可能是一项微不足道的任务，但我根本无法完成它。
Trying to require('./app');in a file deeper in the application produces a undefined object, so I'm guessing that a server is a singleton object.
尝试require('./app');在应用程序更深的文件中生成一个未定义的对象，所以我猜测服务器是一个单例对象。
So what have I tried?
那么我尝试了什么？
My current code looks like this, and somehow I feel like this is the way to go, but I can't apparently do it like this.
我当前的代码看起来像这样，不知何故我觉得这是要走的路，但我显然不能这样做。
I'm omitting all the require();statements to keep it more readable.
我省略了所有require();语句以使其更具可读性。
server.js:
服务器.js：
var app = module.exports = {
preProcess: function onRequest(request, response){
processor.preRequest(request); //this object adds methods on the request object
var path = urllib.parse(request.url).pathname;
router.route(urls, path, request, response);
},
createServer: function() {
console.log("Server start up done.");
return this.server = http.createServer(this.preProcess);
}
};
exports.app = app;
At the time of writing I'm experimenting with extending this object with a get()method.
在撰写本文时，我正在尝试用一种get()方法扩展这个对象。
index.js:
索引.js：
var app = require('./server');
app.createServer().listen('1337');
the router.route()bit basically sends the request onward into the application and inside the router.js-file I do some magic and route the request onward to a function that maps (so far) to the /urlThatWasRequested
该router.route()位基本上将请求向前发送到应用程序和 router.js 文件内部我做了一些魔术并将请求向前路由到映射（到目前为止）到 /urlThatWasRequested 的函数
This is the behavior I'd like to leave behind. I know this might be a pretty tall order but all my code is easily discardable and I'm not afraid of rewriting the entire codebase as this is my own project.
这是我想留下的行为。我知道这可能是一个很高的要求，但我所有的代码都很容易丢弃，而且我不害怕重写整个代码库，因为这是我自己的项目。
I hope this is sufficient in explaining my question otherwise, please say what I should add to make this a bit more clear.
我希望这足以解释我的问题，否则请说我应该添加什么以使这更清楚。
Thanks in advance!
提前致谢！
回答by freakish
I'm not exactly sure what your question is, but here's some thoughts:
我不确定你的问题是什么，但这里有一些想法：
1)You are creating a circular reference here:
1）您在此处创建循环引用：
var app = module.exports = {
// some other code
}
exports.app = app;
You add appas a property of app. There's no need for the last line.
您添加app为 的属性app。不需要最后一行。
2)You need to hold handlers in app. You can try something like this:
2）您需要将处理程序保存在app. 你可以尝试这样的事情：
var app = module.exports = {
handlers : [],
route : function(url, fn) {
this.handlers.push({ url: url, fn: fn });
},
preProcess: function onRequest(request, response){
processor.preRequest(request);
var path = urllib.parse(request.url).pathname;
var l = this.handlers.length, handler;
for (var i = 0; i < l; i++) {
handler = this.handlers[i];
if (handler.url == path)
return handler.fn(request, response);
}
throw new Error('404 - route does not exist!');
},
// some other code
}
Note that you may alter this line: if (handler.url == path)in such a way that handler.urlis a regular expression and you test pathagainst it. Of course you may implement .getand .postvariants, but from my experience it is easier to check whether a request is GETor POSTinsidethe handler. Now you can use the code above like this:
请注意，您可以更改此行：if (handler.url == path)以handler.url正则表达式的方式并path针对它进行测试。当然，您可以实现.get和.post变体，但根据我的经验，检查请求是否在处理程序中GET或POST在处理程序内部更容易。现在你可以像这样使用上面的代码：
app.route('/someUrl', function(req, res){ //do stuff here });
The other thing is that the code I've shown you only fires the firsthandler for a given URL it matches. You would probably want to make more complex routes involving many handlers (i.e. middlewares). The architecture would be a bit different in that case, for example:
另一件事是，我向您展示的代码仅针对它匹配的给定 URL触发第一个处理程序。您可能想要制作涉及许多处理程序（即中间件）的更复杂的路由。在这种情况下，架构会有所不同，例如：
preProcess: function onRequest(request, response){
var self = this;
processor.preRequest(request);
var path = urllib.parse(request.url).pathname;
var l = self.handlers.length,
index = 0,
handler;
var call_handler = function() {
var matched_handler;
while (index < l) {
handler = self.handlers[index];
if (handler.url == path) {
matched_handler = handler;
break;
}
index++;
}
if (matched_handler)
matched_handler.fn(request, response, function() {
// Use process.nextTick to make it a bit more scalable.
process.nextTick(call_handler);
});
else
throw new Error('404: no route matching URL!');
};
call_handler();
},
Now inside your route you can use
现在在您的路线内您可以使用
app.route('/someUrl', function(req, res, next){
//do stuff here
next(); // <--- this will take you to the next handler
});
which will take you to another handler (or throw exception if there are no more handlers).
这将带您到另一个处理程序（如果没有更多处理程序，则抛出异常）。
3)About these words:
3）关于这些话：
Trying to require('./app'); in a file deeper in the application produces a undefined object, so I'm guessing that a server is a singleton object.
试图要求('./app'); 在应用程序更深处的文件中产生一个未定义的对象，所以我猜测服务器是一个单例对象。
It isn't true. requirealways returns the reference to the module object. If you see undefined, then you've messed up something else (altered the module itself?).
这不是真的。require始终返回对模块对象的引用。如果你看到undefined，那么你已经搞砸了其他东西（改变了模块本身？）。
Final note:I hope it helps a bit. Writing your own framework can be a difficult job, especially since there already are excelent frameworks like Express. Good luck though!
最后一点：我希望它有点帮助。编写自己的框架可能是一项艰巨的工作，尤其是因为已经有像 Express 这样的优秀框架。不过祝你好运！
EDIT
编辑
Implementing .getand .setmethods is actually not difficult. You just need to alter routefunction like this:
实现.get和.set方法其实并不难。你只需要route像这样改变功能：
route : function(url, fn, type) {
this.handlers.push({ url: url, fn: fn, type: type });
},
get : function(url, fn) {
this.route(url, fn, 'GET');
},
post : function(url, fn) {
this.route(url, fn, 'POST');
},
and then in routing algorithm you check whether typeproperty is defined. If it is not then use that route (undefinedtype means: always route). Otherwise additionally check if a request's method matches type. And you're done!
然后在路由算法中检查是否type定义了属性。如果不是，则使用该路由（undefined类型表示：始终路由）。否则另外检查请求的方法是否与类型匹配。大功告成！
