Database of legal materials from India includes an international database (left side-bar) with materials from Sri Lanka including case law from Supreme Courts, and other courts, as well as National Legislation.
From Sri Lankan government printing office. Contains full text (free PDF downloads) of acts from 1980-2014-- almost all are in Sinhala, Tamil, and English. This site is very comprehensive in all three languages. (Still in the process of migrating old files to the new site. See old: http://www.documents.gov.lk/old/actspg/acts2006.htm)