下面这个类是获取数据库中一个字段的最大值。配置在数据库中。

public class NoFactory {

	private final static Logger cLogger = Logger.getLogger(NoFactory.class);

	protected static final byte cClusterId = 0;

	protected static final byte cClusterCount = 1;

private static final byte[] BLCTRANNOId = new byte[0];

	private static int BLCTRANNO;

	static {

		try {

			BLCTRANNO = Integer.parseInt(new ExeSQL().getOneValue("select max(to_number(BLCTRANNO)) from edorrenewalbalanceacc where mod(BLCTRANNO,"+cClusterCount+")="+cClusterId));

		} catch (Throwable ex) {

			cLogger.error("初始化最大号异常！", ex);

		}

	}

	public final static int nextBLCTRANNONo() {

		synchronized (BLCTRANNOId) {

			BLCTRANNO += cClusterCount;

		}

		return BLCTRANNO;

	} 

	public final static void setBLCTRANNONo(int pMaxNo) {

		synchronized (BLCTRANNOId) {

			BLCTRANNO = pMaxNo - pMaxNo%cClusterCount + cClusterId;

		}

	}

	}