JDBC 批处理 无法回滚

 /**
		 * 预编译+批处理模式更新数据
		 * */
		@SuppressWarnings("deprecation")
		private boolean batchExecuteInsertTest(){
			boolean isok = true;
			Session session = this.getHibernateTemplate().getSessionFactory().openSession();
			Connection conn=null;//连接
			PreparedStatement pstm=null; //预编译语句
			String pstmSql = null;
			Savepoint sp = null;
			try {
				conn = session.connection();
				conn.setAutoCommit(false); // 设置不自动提交  
				sp = conn.setSavepoint();//设置回滚点
				pstmSql =  "insert into  test(id,name) values (?,?)";
				pstm = conn.prepareStatement(pstmSql);
				
				int recordNum = 1; // 计数器  
	            int commit_size = 2;// 每次提交记录数2
	            pstm.setString(1, "5");//			
	            pstm.setString(2, "5——列数据");		
	            pstm.addBatch();

	            int total = 5;
				//循环队列  
				for (int i = 1; i <= total; i++) {
					recordNum++; // 计数 
					pstm.setString(1, i+"");//
					pstm.setString(2, i+"列数据");//
					pstm.addBatch();
					// 每1000次提交一次
					if (recordNum %  commit_size == 0) {// 可以设置不同的大小；如50，100，500，1000等等
						pstm.executeBatch();
						conn.commit();
						pstm.clearBatch();
						conn.setAutoCommit(false);  
						pstm = conn.prepareStatement(pstmSql); 
					}
					
				} 
				if (recordNum % commit_size != 0) { //执行剩余的批处理
					pstm.executeBatch();  
	                conn.commit();  
	            }  
				
			} catch (Exception e) {
				isok = false;
				e.printStackTrace();
				try {  
	                if (conn != null) {  // 回滚事务   
	                	conn.rollback(sp);//回滚到那个事务点上去
	                    conn.commit();
	                }
	             } catch(Exception e2){
	         	 } 
			}finally{
				try {
					if (pstm != null) {
						pstm.close();
						pstm = null;
					}
					if (conn != null) {
						conn.close();
						conn = null;
					}
					if (session != null) {
						session.close();
						session = null;
					}
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
			return isok;
		}

 

我设置2条记录进行提交，当执行到第6条语句时，由于主键唯一性，无法执行。却没有事务回滚，不知道怎么回事？希望各位高手指点！