You can do something similar to PhoenixRuntime.decodeColumnValues() to do that. It'd be something like this:
public static Object[] decodeColumnValues(Connection conn, String fullTableName, byte[] value) throws SQLException {
PTable table = getTable(conn, fullTableName);
RowKeySchema schema = table.getRowKeySchema();
ImmutableBytesWritable ptr = new ImmutableBytesWritable(value);
schema.iterator(ptr);
int i = 0;
List<Object> values = new ArrayList<Object>();
while(schema.next(ptr, i, maxOffset) != null) {
values.add(schema.getField(i).getDataType().toObject(ptr));
i++;
}
return values.toArray();
}