java - 不能将 resultSet.setFetchDirection(ResultSet.TYPE_SCROLL_SENSITIVE) 与 spring jdbc DaoSupport 与 Oracle 一起使用

Question

我想使用可滚动的结果集，所以当我使用两行代码时:

 rs.setFetchDirection(ResultSet.TYPE_SCROLL_SENSITIVE);
rs.absolute(12);

在我的 DAOimpl 中，我遇到异常，请帮助解决它们，在此先感谢。

 import oracle.jdbc.OracleTypes;
    import org.springframework.jdbc.core.CallableStatementCallback;
    import org.springframework.jdbc.core.support.JdbcDaoSupport;
    import org.springframework.stereotype.Component;
    @Component
    public class MyDAOimpl extends JdbcDaoSupport implements
            MyDAO {

        public List<User> getList(final String where) throws Exception {

            return (List) getJdbcTemplate().execute(
                    "{call PKG_USER.getUser(?,?)}",
                    new CallableStatementCallback() {
                        public Object doInCallableStatement(CallableStatement cs)
                                throws SQLException {

                            cs.setString(1, where);
                            cs.registerOutParameter(2, OracleTypes.CURSOR);
                            cs.execute();

                            ResultSet rs = (ResultSet) cs.getObject(6);

                            rs.setFetchDirection(ResultSet.TYPE_SCROLL_SENSITIVE);
                            rs.absolute(12);

                            List<User> list = new ArrayList<User>();

                            while (rs.next()) {

                                User user = new User(
                                        rs.getString(1),
                                        rs.getString(2), 
                                        rs.getString(3));
                                list.add(user);
                            }
                            return list;
                        }
                    });

        }
    }

这是异常(exception)

java.sql.SQLException: Invalid argument(s) in call: setFetchDirection
    oracle.jdbc.driver.SQLStateMapping.newSQLException(SQLStateMapping.java:70)
    oracle.jdbc.driver.DatabaseError.newSQLException(DatabaseError.java:133)
    oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:199)
    oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:263)
    oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:271)
    oracle.jdbc.driver.BaseResultSet.setFetchDirection(BaseResultSet.java:128)

/////////////////////////////////////////////////////////////////////////////////////////

我像下面这样更改的地方，我没有得到任何结果，通常，我的程序返回 100 个用户:

return (List) getJdbcTemplate().execute(new CallableStatementCreator() {

            public CallableStatement createCallableStatement(
                    Connection connection) throws SQLException {
                return connection.prepareCall(
                        "{call PKG_USER.getUser(?,?)}",
                        ResultSet.TYPE_SCROLL_SENSITIVE,
                        ResultSet.TYPE_SCROLL_INSENSITIVE);
            }
        }, new CallableStatementCallback() {

            public Object doInCallableStatement(CallableStatement cs)
                    throws SQLException, DataAccessException {

                cs.setString(1, where);
                cs.registerOutParameter(2, OracleTypes.CURSOR);
                cs.execute();

                ResultSet rs = (ResultSet) cs.getObject(6);

                //////not run////
                rs.absolute(12);
                ////////////////

                List<User> list = new ArrayList<User>();

                while (rs.next()) 
                {   
                    List<User> list = new ArrayList<User>();

                            while (rs.next()) {

                                User user = new User(
                                        rs.getString(1),
                                        rs.getString(2), 
                                        rs.getString(3));
                                list.add(user);
                            }
                            return list;
            }
        });

Answer 1

首先，ResultSet.TYPE_SCROLL_SENSITIVE 是一个指示结果集类型 的常量，当然不是 setFetchDirection 的有效参数，它需要一个 < em>正确的方向。引用 ResultSet#setFetchDirection(int direction) 的 javadoc 的参数部分:

direction - an int specifying the suggested fetch direction; one of ResultSet.FETCH_FORWARD, ResultSet.FETCH_REVERSE, or ResultSet.FETCH_UNKNOWN

因此出现异常和消息“调用中的参数无效:setFetchDirection”。

顺便说一句，根据 Oracle 的“JDBC Developer's Guide and Reference”(所有版本都可以从 http://tahiti.oracle.com/ 获得)在 Processing a Scrollable Result Set 中:

Presetting the Fetch Direction

The JDBC 2.0 standard allows the ability to pre-specify the direction, known as the fetch direction, for use in processing a result set. This allows the JDBC driver to optimize its processing. The following result set methods are specified:

• void setFetchDirection(int direction) throws SQLException * int getFetchDirection() throws SQLException

The Oracle JDBC drivers support only the forward preset value, which you can specify by inputting the ResultSet.FETCH_FORWARD static constant value.

The values ResultSet.FETCH_REVERSE and ResultSet.FETCH_UNKNOWN are not supported. Attempting to specify them causes a SQL warning, and the settings are ignored.

readme 中也提到了这一点的 Oracle Database 11g Release 2 JDBC Drivers (撰写本文时的最终版本):

The scrollable result set implementation has the following limitation:

• setFetchDirection() on ScrollableResultSet does not do anything.

但所有这些都是一种旁注，使用 setFetchDiretion 根本不是获得可滚动结果集的方法。

要使用 Spring 的 JdbcTemplate 创建可滚动的结果集，您实际上应该使用方法 execute(CallableStatementCreator csc, CallableStatementCallback action)与自定义 CallableStatementCreator执行。在此实现中，使用方法 Connection.prepareCall(String sql, int resultSetType, int resultSetConcurrency)创建一个 CallableStatement，它将生成具有给定类型和并发性的 ResultSet 对象。最后，调用 rs.absolute()。

---

更新: connection.prepareCall() 调用有问题，第三个参数应该是并发类型(ResultSet.CONCUR_READ_ONLY 或 ResultSet.CONCUR_UPDATABLE)。试试这个:

            return connection.prepareCall(
                    "{call PKG_USER.getUser(?,?)}",
                    ResultSet.TYPE_SCROLL_SENSITIVE,
                    ResultSet.CONCUR_UPDATABLE);