Java, universal language in Internet, used in everywhere and every field, makes people charming in the broad, wonderful world of Internet. This paper makes a deep research into the connectivity of Java and DB,and gives some way by which Java programmes visit DB, especially how JDBC sets up a connection with DB,how data are got and saved and how to deal with exception. What is move, by some examples, this paper shows in details the proccess Java programmes visit DB by JDBC.