Attach a File to an Object in Apex

I left out the visual force, but here is the apex code.  In this case I'm associating the attachment to a new case that's created.

   1:  public class MyController{

   2:   

   3:      public Attachment attachment {

   4:        get {

   5:            if (attachment == null){

   6:              attachment = new Attachment();

   7:            }

   8:            return attachment;

   9:          }

  10:        set;

  11:      }

  12:      

  13:      

  14:      public void myFunction() {

  15:        try{

  16:              

  17:          Case c = new Case;

  18:          /* Do all the stuffs to the case object */

  19:          INSERT c;

  20:               

  21:          attachment.OwnerId = UserInfo.getUserId();

  22:          attachment.ParentId = c.id;

  23:          attachment.IsPrivate = false;

  24:          try {

  25:            insert attachment;

  26:          } catch (DMLException e) {

  27:            ApexPages.addMessage(new ApexPages.message(ApexPages.severity.ERROR,'Error uploading attachment'));

  28:          } finally {

  29:            attachment = new Attachment(); 

  30:          }  

  31:        }

  32:      }

  33:  }