数据量大时处理。

// 生成自测成绩 lizhuang 2012年8月6日
	@SuppressWarnings("unchecked")
	public String makeTestScore() {
		dbpool pool = new dbpool();
		Connection conn = pool.getConn();
		Statement ps = null;
		try {
		
			ps = conn.createStatement();
			for (int j = 0; j < stuList.size(); j++) {
				String sql = "UPDATE pe_bzz_examscore t  SET t.test_score=IFNULL((select round(s.AVG_test_score,1) from stat_study_summary s" + " where s.student_id=0;";
				ps.addBatch(sql);
				
				if (StringUtils.isNotBlank(stuList.get(j).getTotal_score())) {
					Double total_score = (Double.parseDouble(exam_score) * exam_scale + Double.parseDouble(test_score) * test_scale) / 100;
					String totalScore = df.format(total_score);
					sql = "update pe_bzz_examscore t set t.total_score=" + totalScore + " where t.id='" + stuList.get(j).getId() + "';";
					ps.addBatch(sql);
				}
				// 如果考核等级不为空，同步更新
				if (StringUtils.isNotBlank(stuList.get(j).getTotal_grade())) {
					String grade = null;
					Double total_score = Double.parseDouble(stuList.get(j).getTotal_score());
					if (total_score < 60) {
						grade = "不及格";
					} else if (total_score >= 60 && total_score < 75) {
						grade = "合格";
					} else if (total_score >= 75 && total_score < 90) {
						grade = "良好";
					} else if (total_score >= 90) {
						grade = "优秀";
					}
					sql = "update pe_bzz_examscore t set t.total_grade='" + grade + "'where t.id='" + stuList.get(j).getId() + "';";
					ps.addBatch(sql);
				}
				if (j == stuList.size() - 1) {// 如果到达末尾，全部提交
					ps.executeBatch();
					break;
				}
				if (j % 200 == 0 && j != 0) {// 每200条批量提交一次
					ps.executeBatch();
				}
			}
			ps.close();
			conn.close();
		} catch (Exception e1) {
			e1.printStackTrace();
			request().setAttribute("msg", "生成失败。");
			return "extmsg";
		}
		request().setAttribute("msg", "全部生成成功！");
		// request().setAttribute("url",
		// "/entity/exam/peBzzExamScore.action?tag=search");
		return "extmsg";
	}

addBatch