nodejs express route 的用法

From: http://node-js.diandian.com/post/2012-07-03/40029072624

nodejs express route 的用法

1. 首先是最基本的用法。

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var app=require( 'express' ).createServer();                                                     app.get( "/" , function (req,res){                                                          res.send( "hello world" );                                                     });                                                     app.listen(3000);

當用戶訪問 127.0.0.1:3000的時候，頁面會輸出hello world

2. 加個路徑試試。

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var app=require( "express" ).createServer();                                                                                                                                                   app.get( "/toolmao" , function (req,res){                                                     res.send( "welcome to toolmao" );                                                });                                                                                                                                                   app.listen(3000);

當用戶訪問 127.0.0.1:3000/toolmao的時候，就會輸出welcome to toolmao

3. 更爲複雜一點的，能夠把路徑做爲參數。

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var app=require( "express" ).createServer();                                                                                                                                       app.get( '/user/:id' , function (req, res){                                                 res.send( 'user ' + req.params.id);                                            });                                                                                                                                       app.listen(3000);

當用戶訪問 127.0.0.1:3000/user/gainover 的時候，就會輸出 user gainover

4. 3中的代碼，也能夠寫爲正則表達式的形式。

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var app=require( "express" ).createServer();                                                                                                                           app.get(/\/user\/([^\/]+)\/?/, function (req, res){                                             res.send(req.params);                                        });                                                                                                                           app.listen(3000);

這裏能夠根據你的須要進行正則的自定義。正則中的匹配結果，存儲在req.params參數中。

一個更復雜的正則的例子，以下：含有2個匹配。

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app.get(/^\/users?(?:\/(\d+)(?:\.\.(\d+))?)?/, function (req, res){                                        res.send(req.params);                                   });

請求時，輸出以下：

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$ curl http: //dev:3000/user                                 [ null , null ]                                 $ curl http: //dev:3000/users                                 [ null , null ]                                 $ curl http: //dev:3000/users/1                                 [ "1" , null ]                                 $ curl http: //dev:3000/users/1..15                                 [ "1" , "15" ]

5. 若是咱們想指定參數爲id，同時又想用正則進行限制，能夠寫爲：

/user/:id([0-9]+)

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Route的依次執行

1. 當一個請求，可以匹配到多個route時，咱們能夠調用內置的next函數，來依次進行處理。

例如：

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app.get( '/users/:id?' , function (req, res, next){                             var id = req.params.id;                             if (id) {                                 // do something                             } else {                                 next();                             }                        });                                                                           app.get( '/users' , function (req, res){                             // do something else                        });

當用戶請求，/users/gainover時，能夠進行某種處理，而當用戶請求爲/users/, id 不存在，則會調用next()函數，進而調用 app.get("/users/", ....);

2. 一個route裏能夠有多個處理函數。例如：

app.get('/users/:id/edit/',function1,function2,...);

一個實際的例子可能以下：

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function loadUser(req, res, next) {               // You would fetch your user from the db               var user = users[req.params.id];               if (user) {                 req.user = user;                 next();               } else {                 next( new Error( 'Failed to load user ' + req.params.id));               }            }            function andRestrictToSelf(req, res, next) {               req.authenticatedUser.id == req.user.id                 ? next()                 : next( new Error( 'Unauthorized' ));            }                                       app.get( '/user/:id/edit' , loadUser, andRestrictToSelf, function (req, res){               res.send( 'Editing user ' + req.user.name);            });

當用戶訪問：/user/gainover/edit時，首先會調用第一個處理函數loadUser，判斷用戶是否存在於users中，若是不存在，經過next(new Error(msg)); 的方式拋出異常，不然，執行next()，而next此時實際就是指向 andRestrictToSelf 函數，而後判斷當前登陸的id和被編輯的id是否等同，若是等同，則繼續next()，從而執行 res.send( ...);