So close. opendir/readdir is the equivalent of ls or dir; it just lists the directory content. Assuming you want to read the contents of the file, you need to open them, too, a la:

foreach my $file (@files) {
    next unless -f "$directory/$file";
    open my $fh, '<', "$directory/$file" or die "Open failed on $file:
+ $!";
    while (<$fh>) {
        next if /^\s$/;        # skip blank lines
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Also note the use of -f to check that you're dealing with an ordinary file before opening and actually testing that the file open worked.