Loading properties file from WEB-INF folder in a log4j appender
InputStream stream = Thread.currentThread().getContextClassLoader()
                    .getResourceAsStream("jdbc.properties");

String  path =Thread.currentThread().getContextClassLoader().getResource("/").toURI().resolve("../jdbc.properties").getPath();
 Properties ps=new Properties();
 ps.load(new FileInputStream(path));

ServletContext ctx = ...
InputStream stream = ctx.getResourceAsStream("/WEB-INF/jdbc.properties");