How to read a file into a variable in shell?

I want to read a file and save it in variable, but I need to keep the variable and not just print out the file.
How can I do this? I have written this script but it isn’t quite what I needed:

#!/bin/sh
while read LINE  
do  
  echo $LINE  
done <$1  
echo 11111-----------  
echo $LINE  

In my script, I can give the file name as a parameter, so, if the file contains “aaaa”, for example, it would print out this:

aaaa
11111-----

But this just prints out the file onto the screen, and I want to save it into a variable!
Is there an easy way to do this?