NJM78L09UA alternative
You can find equivalents at Digikey or Mouser, and others, as the links above indicate. 

A 9V battery cannot give you a stable 9V output with a linear regulator such as an LM78L09. If the current is modest, a 5V output (using LM78L05) is possible with reasonable battery life. Here, from a typical alkaline 9V cell, you can see the lifetime vs. EOL voltage. 



A 78L05 would give you 5V with maybe 40 hours life with 10mA (including the few mA the regulator draws) but a better LDO regulator could give you more like 75 hours life (and closer to 90 hours if it was a low power CMOS type). At $2/battery the better regulator pays for itself pretty quickly.