Download file in Attachments in Salesforce

public class ex_file_inSF { 

public void getExcelReport() {

String AccId = ApexPages.currentPage().getParameters().get('id'); 

Account acc = [Select Id from Account where Id =: AccId]; 

Http h = new Http(); 

HttpRequest req = new HttpRequest(); 

string url = 'URL_Path'; url = url.replace(' ', '%20');

req.setEndpoint(url); 

req.setMethod('GET'); 

req.setHeader('Content-Type', 'application/xls'); 

// To download Pdf 'application/pdf' 

// To download Document 'application/doc' 

// To download img 'image/jpeg' 

req.setCompressed(true); 

req.setTimeout(120000); 

HttpResponse res = null; 

res = h.send(req);

/*string responseValue = ''; 

responseValue = res.getBody(); 

system.debug('Response Body for File: ' + responseValue); */ 

blob file = res.getBodyAsBlob(); 

Attachment n = new Attachment(); 

n.ParentId = AccId; //set where you want to Save/Attach file 

n.Name = 'Excel_Report.xls'; 

n.Body = file; 

n.contentType = 'application/xls'; 

// To download Pdf 'application/pdf' 

// To download Document 'application/doc' 

// To download img 'image/jpeg' insert n; 

} 

}

Reference: http://nanostuffs.com/Blog/?p=1451