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);

当用户访问 127.0.0.1:3000的时候，页面会输出hello world

2. 加个路径试试。

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

当用户访问 127.0.0.1:3000/toolmao的时候，就会输出welcome to toolmao

3. 更为复杂一点的，可以把路径作为参数。

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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);

当用户访问 127.0.0.1:3000/user/gainover 的时候，就会输出 user gainover

4. 3中的代码，也可以写为正则表达式的形式。

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

这里可以根据你的需要进行正则的自定义。正则中的匹配结果，存储在req.params参数中。

一个更复杂的正则的例子，如下：含有2个匹配。

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

请求时，输出如下：

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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. 如果我们想指定参数为id，同时又想用正则进行限制，可以写为：

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

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Route的依次执行

1. 当一个请求，能够匹配到多个route时，我们可以调用内置的next函数，来依次进行处理。

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                        });

当用户请求，/users/gainover时，可以进行某种处理，而当用户请求为/users/, id 不存在，则会调用next()函数，进而调用 app.get("/users/", ....);

2. 一个route里可以有多个处理函数。例如：

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

一个实际的例子可能如下：

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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);            });

当用户访问：/user/gainover/edit时，首先会调用第一个处理函数loadUser，判断用户是否存在于users中，如果不存在，通过next(new Error(msg)); 的方式抛出异常，否则，执行next()，而next此时实际就是指向 andRestrictToSelf 函数，然后判断当前登录的id和被编辑的id是否等同，如果等同，则继续next()，从而执行 res.send( ...);