我有一个目录结构
projectName
    | - bower_components/
    | - public/
        | - css
        | - js
        | - index.html
    | - Gruntfile.js
    | - package.json
    | - bower.json
    | - app.js
我想启动我的应用程序并使用 node.js 服务index.html。所以在app.js我有:
var express = require('express');
var port = process.env.PORT || 3000;
var app = express();
app.configure(function(){
    // Serve up content from public directory
    app.use(express.static(__dirname + '/public'));
    app.use(app.router);
    app.use(express.logger()); 
});
app.listen(port, function(){
    console.log('Express server listening on port ' + port);
});
在index.html我的底部有:
<script src="../bower_components/jquery/jquery.js"></script>
<script src="../bower_components/d3/d3.js"></script>
<script src="../bower_components/bootstrap/dist/js/bootstrap.js"></script>
<script src="bower_components/spin.js/spin.js"></script>
<script src="bower_components/mustache/mustache.js"></script>
当我启动服务器时,index.html显示但没有加载上述库。我收到错误(404):
GET http://localhost:3000/bower_components/jquery/jquery.js 404 (Not Found) localhost/:32
GET http://localhost:3000/bower_components/d3/d3.js 404 (Not Found) localhost/:33
GET http://localhost:3000/bower_components/bootstrap/dist/js/bootstrap.js 404 (Not Found) localhost/:34
GET http://localhost:3000/bower_components/spin.js/spin.js 404 (Not Found) localhost/:35
GET http://localhost:3000/bower_components/mustache/mustache.js 404 (Not Found) 
如何从 bower_components 提供文件?