Getting SharePoint objects (spweb, splist, splistitem) from url string

You basically get anything in the object model with one full url:

//here is the site for the url
using (SPSite site = new SPSite("http://basesmcdev2/sites/tester1/tester4/A0805051340564172608.txt"))
{
       //here is the web for the url
       using (SPWeb web = site.OpenWeb())
       {
              //here is the file for the url
              SPFile file = web.GetFile("http://basesmcdev2/sites/tester1/tester4/A0805051340564172608.txt");
 
              //here is the list for the url
              SPList list = file.Item.ListItems.List;
 
              //here is the list item for the url
              SPListItem item = file.Item;
       }
}