Hibernate Session 获取connection

Hibernate Session 获取connection

由于最近一个项目要用到一条辅助的SQL ,hibernate里面的SQLQuery API 总的SQL语句不能包含 : 冒号, 固放弃Hibernate, 直接使用JDBC.

Hibernate3.3.2版本中getSession().connection()已被弃用，替代方法

SessionFactoryUtils.getDataSource(getSessionFactory()).getConnection()

原有方法

getSession().connection()

来自类org.springframework.orm.hibernate3.SessionFactoryUtils

例子：

      

  java.sql.Connection c = null;
        java.sql.PreparedStatement ps = null;
        java.sql.ResultSet rs = null;

public List method(String sql) {
        List ret = new ArrayList();
        try {
        c = SessionFactoryUtils.getDataSource(getSessionFactory()).getConnection();
            ps = c.prepareStatement(sql);
            rs = ps.executeQuery();
            while(rs.next()) {
                 .....
                }
                ret.add(ro);
            }
        } catch (Exception e) {
             e.printStackTrace();

       } finally {
           close();
        }
        return ret;
    }

我的demo

/**
     * 
     * 
     * @author mjorcen
     * @email mjorcen@gmail.com
     * @dateTime Jul 4, 2014 5:43:05 PM
     * @version 1
     * @throws SQLException
     */
    private void getTop() throws SQLException {
        StringBuilder sb = new StringBuilder();
        sb.append("SELECT X.COMMENT_ID, X.TOTAL_NO, X.ORDER_NO, IFNULL(X.ORDER_NO / X.TOTAL_NO, 1) AS PERCENTAGE_NO  ");
        sb.append("FROM (SELECT @rowNum := @rowNum + 1 AS ORDER_NO, @rowCount AS TOTAL_NO, t.COMMENT_ID, t.COMMENT_SPENDING  ");
        sb.append("    FROM T_SD_COMMENT t, (SELECT @rowNum := 0  ");
        sb.append("        ) b, (SELECT @rowCount := (  ");
        sb.append("                SELECT COUNT(*)  ");
        sb.append("                FROM T_SD_COMMENT  ");
        sb.append("                WHERE to_days(CREATE_TIME) >= to_days(now())  ");
        sb.append("                )  ");
        sb.append("        ) c  ");
        sb.append("     WHERE to_days(t.CREATE_TIME) >= to_days(now()) ORDER BY t.COMMENT_SPENDING ,t.COMMENT_ID ");
        sb.append("    ) X  ");
        sb.append("WHERE X.COMMENT_ID = ?  ");
        Connection c = this.commentService.getSession().connection();
        PreparedStatement ps = c.prepareStatement(sb.toString());
        ps.setInt(1, this.paramComment.getCommentId());
        ResultSet rs = ps.executeQuery();
        if (rs.next()) {
            System.out.println("COMMENT_ID = " + rs.getInt("COMMENT_ID"));
            System.out.println("TOTAL_NO = " + rs.getInt("TOTAL_NO"));
            System.out.println("ORDER_NO = " + rs.getInt("ORDER_NO"));
            System.out.println("PERCENTAGE_NO = " + rs.getDouble("PERCENTAGE_NO"));
        }
    }

Hibernate API中让使用doWork(Work,work)，描述如下：

connection() 
          Deprecated. (scheduled for removal in 4.x). Replacement depends on need; for doing direct JDBC stuff use doWork(org.hibernate.jdbc.Work); for opening a 'temporary Session' use (TBD).

Work接口的execute()方法用于执行直接通过JDBC API来访问数据库的操作：

public interface Work {
    // 直接通过JDBC API来访问数据库的操作
    public void execute(Connection connection) throws SQLException;
}

 Session的doWork(Work  work)方法用于执行Work对象指定的操作，即调用Work对象的execute()方法。

 Session会把当前使用的数据库连接传给execute()方法。

 过程如下：

Transaction tx = session.beginTransaction();
    // 定义一个匿名类，实现了Work接口
    Work work = new Work() {
        public void execute(Connection connection) throws SQLException {
            // 通过JDBC API执行用于批量更新的SQL语句
            PreparedStatement stmt = connection
                    .prepareStatement("update CUSTOMERS set AGE=AGE+1 "
                            + "where AGE>0 ");
            stmt.executeUpdate();
        }
    };

执行work

session.doWork(work);
tx.commit();

当通过JDBC API中的PreparedStatement接口来执行SQL语句时，SQL语句中涉及到的数据不会被加载到Session的缓存中，因此不会占用内存空间。