jdbc连接oracle数据库问题

下面是JDBC连接oracle数据库流程：
String dbURL = “jdbc:oracle:thin:@url:1521:service_name”;

    String userName = &#34;数据库名&#34;;<br/>
    String userPwd = &#34;密码&#34;;<br/>
    Connection con = null;<br/>
    Statement st = null;<br/>
    ResultSet rs = null;    

try {

        Class.forName(&#34;oracle.jdbc.driver.OracleDriver&#34;);<br/>
        con = DriverManager.getConnection(dbURL, userName, userPwd);<br/>
        System.out.println(&#34;加载数据库驱动成功！&#34;);<br/>
        System.out.println(&#34;数据库连接成功！&#34;);<br/>
        st = con.createStatement();

String sql = “select * from ETL.BD_PSNDOC”;//数据库表名前面尽量加上数据库名字 rs = st.executeQuery(sql);

        while (rs.next()) {<br/>
          .......................<br/>
         }<br/>
    }catch(Exception e){<br/>
        e.printStackTrace();<br/>
    }<br/>
    try {<br/>
        if(rs!=null){<br/>
            rs.close();<br/>
        }<br/>
        if (st != null) {<br/>
            st.close();<br/>
        }<br/>
        if (con != null) {<br/>
            con.close();<br/>
        }<br/>
    } catch (Exception e) {<br/>
        e.printStackTrace();<br/>
    }