[SalesForce] Get xls File on Remote Server and Send as Email Attachment APEX

I have an xls file sitting on www.mysite.com/files/myfile.xls. I would like to have SalesForce via APEX grab (Not Read) this file and send it as an attachment to an email.

I know how to send emails in SalesForce via APEX, however I'm not sure how to:
1. Grab a file on a remote server with APEX
2. Attach this file to an email and send from APEX.

I have looked over the web for solutions on the first and have only come across a few unanswered questions.

I have looked over the below info about attachments, but not sure if xls files can be used in the getContent() method. First thing I wanted to get figured out is the grabbing a file from a server.
http://www.salesforce.com/us/developer/docs/pages/Content/pages_email_sending_attachments.htm

I believe I could POST the file from that server via PHP to SalesForce and invoke an APEX class, but I was hoping to do it all from SF to avoid logging in as a user.

Any help is greatly appreciated.

I've tested out the solution below, but I believe I am not putting in the correct URL. My code is below, and the error I receive is:

Error:

A problem with the OnClick JavaScript for this button or link was encountered:

{faultcode:'soapenv:Client', faultstring:'System.VisualforceException: No Visualforce context has been established!

Class.AccountExcelGetAndEmail.getExcelFile: line 18, column 1', }

Code:

global class AccountExcelGetAndEmail {


WebService static void getExcelFile(string id){

List<User>Users = [SELECT id From User Where email = 'infoSys@mycompany.com' AND name = 'API Admin'];
User testUser = Users[0];


PageReference ref = new PageReference('http://dev.mysite.com/sf/PHPExcel_1_7_9/testCSV%20-%20Copy.xls');
system.debug('Page Ref'+ref);
Blob b = ref.getContent();
Messaging.SingleEmailMessage m = new Messaging.SingleEmailMessage();
m.setTargetObjectId(testUser.id);
Messaging.EmailFileAttachment a = new Messaging.EmailFileAttachment();
a.setBody(b);
a.setContentType('application/vnd.ms-excel');
a.setFileName('some-file.xls');
a.setInline(false);
m.setFileAttachments(new Messaging.EmailFileAttachment[] { a } );
m.setSubject('Test');
m.setPlainTextBody('See attachment');
m.setSaveAsActivity(false);
Messaging.sendEmail(new Messaging.SingleEmailMessage[] { m } );

}

}

However, per this page, I am referencing a page properly.

http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_pages_pagereference.htm

Update: Its not because I am calling a file vs a web page. If I set the page reference to

PageReference ref = new PageReference('http://www.mysite.com');

The same error still occurs.

Solution

I ended up using HTTP Request/Response as suggested it could be done this way over PageReference. Never did figure out why PageReference would not work but HTTP Request/Response does?
Code is below: ( I removed wrapper class and webservice class. this code would go in the webservice class)

        List<User>Users = [SELECT id From User Where email = 'testUser@gmail.com'];
    User testUser = Users[0];
    // Instantiate a new http object
        Http h = new Http();
        String url = 'http://mysite.com;
    // Instantiate a new HTTP request, specify the method (GET) as well as the endpoint
        HttpRequest req = new HttpRequest();
        req.setEndpoint(url);
        req.setMethod('GET');

    // Send the request, and return a response
        HttpResponse res = h.send(req);
        //system.debug(res.getBody());


    Blob myBlob = res.getBodyAsBlob(); 
    Messaging.SingleEmailMessage m = new Messaging.SingleEmailMessage();
    m.setTargetObjectId(testUser.id);
    Messaging.EmailFileAttachment a = new Messaging.EmailFileAttachment();
    a.setBody(myBlob);
    a.setFileName('some-file.xls');
    a.setInline(false);
    m.setFileAttachments(new Messaging.EmailFileAttachment[] { a } );
    m.setSubject('Test');
    m.setPlainTextBody('See attachment');
    m.setSaveAsActivity(false);
    Messaging.sendEmail(new Messaging.SingleEmailMessage[] { m } );

Thank you sfdcfox!