小编atr*_*thi的帖子

我使用JDBC批量插入插入许多记录.有没有办法获得每条记录的生成密钥？我可以使用ps.getGeneratedKeys()批量插入吗？

我在用 oracle.jdbc.OracleDriver

final String insert = "Insert into Student(RollNumber, Name, Age) values(StudentSEQ.nextval, ? , ?)";
final int BATCH_SIZE = 998;
int count = 0;
Connection con = null;
PreparedStatement ps =  null;
try {
    con = getConnection();
    ps = con.prepareStatement(insert);
    for (Student s : students) {
        ps.setString(1, s.getName());
        ps.setInt(2, s.getAge());
        ps.addBatch();
        count++;
        if (count % BATCH_SIZE == 0) {
        // Insert records in batches
            ps.executeBatch();
        }
    }
    // Insert remaining records
    ps.executeBatch();
} finally {
    if(ps != …

我必须使用hibernate将大量对象保存到数据库中.我想在会话中出现n(BATCH_SIZE)对象时提交,而不是一次提交所有这些对象.

Session session = getSession();
session.setCacheMode(CacheMode.IGNORE);
for(int i=0;i<objects.length;i++){
    session.save(objects[i]);
    if( (i+1) % BATCH_SIZE == 0){
        session.flush();
        session.clear();
    }
}

我会尝试类似上面的东西,但我读到session.flush()它没有提交数据库的更改.这是以下代码正确的方法吗？

Session session = getSession();
session.setFlushMode(FlushMode.COMMIT);
session.setCacheMode(CacheMode.IGNORE);
session.beginTransaction();
for(int i=0;i<objects.length;i++){
    session.save(objects[i]);
    if( (i+1) % BATCH_SIZE == 0){
        session.getTransaction().commit();
        session.clear();
        //should I begin a new transaction for next batch of objects?
        session.beginTransaction();
    }
}
session.getTransaction().commit();

我是否需要手动关闭从休眠会话中获得的连接？

如果我这样做，我会关闭连接池中的一个连接吗？

如果我不这样做，休眠会自动关闭连接吗？

            Connection con = null;
            PreparedStatement ps = null;
            ResultSet rs = null;

            String query = "sql query";
            try {
                Session session = this.sessionFactory.getCurrentSession();
                con = session.connection();
                ps = con.prepareStatement(query);
                rs = ps.executeQuery();
                while (rs.next()) {
                    //read result set
                }
            } catch (SQLException exp) {
                log.error("Error: ", exp);
            } finally{
               if(ps != null)
                   ps.close();
               if(con != null)
                   con.close();  //Is this required?
            }

我有一个阵列

String[] grades = new String[]{"D","C-","C","C+","B-","B","B+","A-","A","A+"};

我想检查字符串是否是这些值之一.

我可以遍历数组来实现这一目标,但我希望通过正则表达式完成.