Java 调用 Oracle 存储过程返回结果集

Oracle 存储过程返回结果集用 ref cursor 实现。
试验步骤如下：
1. 建立 ref cursor 类型和过程
CREATE OR REPLACE PACKAGE types
AS
    TYPE ref_cursor IS REF CURSOR;
END;
/
CREATE TABLE STOCK_PRICES(
    RIC VARCHAR(6) PRIMARY KEY,
    PRICE NUMBER(7,2),
    UPDATED DATE );
/
CREATE OR REPLACE FUNCTION sp_get_stocks(v_price IN NUMBER)
    RETURN types.ref_cursor
AS
    stock_cursor types.ref_cursor;
BEGIN
    OPEN stock_cursor FOR
    SELECT ric,price,updated from stock_prices WHERE price < v_price;
    RETURN stock_cursor;
END;
2. 用 sqlplus 测试过程
SQL> var results refcursor
SQL> exec :results := sp_get_stocks(20.0)
SQL> print results
3. 从 Java 调用
import java.sql.*;
import java.io.*;
import oracle.jdbc.driver.*;
public class JDBCDemo {
    /**
    * Compile-time flag for deciding which query to use
    */
    private boolean useOracleQuery = true;
    /**
    * Class name of Oracle JDBC driver
    */
    private String driver = "oracle.jdbc.driver.OracleDriver";
    /**
    * Initial url fragment
    */
    private String url = "jdbc:oracle:thin:@";
    /**
    * Standard Oracle listener port
    */
    private String port = "1521";
    /**
    * Oracle style of calling a stored procedure
    */
    private String oracleQuery = "begin ? := sp_get_stocks(?); end;";
    /**
    * JDBC style of calling a stored procedure
    */
    private String genericQuery = "{ call ? := sp_get_stocks(?) }";
    /