获得数据库自动生成的主键

Connection conn = JdbcUtil.getConnection();

String sql = "insert into user(name,password,email,birthday) 
            values('abc','123','abc@sina.com','1978-08-08')";
PreparedStatement st = conn.
            prepareStatement(sql,Statement.RETURN_GENERATED_KEYS );//此参数仅对insert操作有效。

st.executeUpdate();
ResultSet rs = st.getGeneratedKeys();  //得到插入行的主键
if(rs.next())
    System.out.println(rs.getObject(1));