转：按日期递增序列号工具类（java）

最新推荐文章于 2022-12-27 11:58:53 发布

chenshou6444

最新推荐文章于 2022-12-27 11:58:53 发布

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文章标签： java 数据库

原文链接：https://my.oschina.net/xf1025/blog/856689

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本文介绍了一个使用Java实现的流水号生成器，该生成器能够根据日期和前缀生成唯一的流水号，适用于需要唯一标识符的场景。通过同步机制确保了多线程环境下的安全性，并利用HashMap缓存实例，提高了效率。

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import java.text.Format;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

//按日期生成流水号，每次重启后需要在config afterJFinalStart 启动之后调用id初始化代码 
//1.如果数据有数据，取当日最大值加1 ，2。如果数据无数据，初始化为1
//调用：SerialUtil.newInstance("BDCID", new Date()).toString();
//BFCID 为调取那个表格的标识，代码区分标识调用
/*显示当前日期 20160101
 long date = DateUtil.getYear() * 10000 + DateUtil.getMonth() * 100
 + DateUtil.getDay();
 // 系统启动后获取数据库业务流水号
 BigDecimal dBG = Db
 .queryBigDecimal("SELECT MAX(bdid) FROM (SELECT MAX(BDID) as BDID FROM BUSI_DATA WHERE CONVERT(VARCHAR(10),BARCHTIME,23)= CONVERT(VARCHAR(10),GETDATE(),23) UNION ALL SELECT MAX(BDID) as BDID FROM busi_data_allot WHERE CONVERT(VARCHAR(10),BARCHTIME,23)= CONVERT(VARCHAR(10),GETDATE(),23)) as B");
 if (dBG != null) {
 long ret = dBG.longValue() - (date * 100000000);
 SerialUtil.newInstance("BDID", new Date()).setNumber((int) ret);
 }
 */

public class SerialUtil {
	private static final int MAX_VALUE = 99999999;

	private static final String FORMAT = "yyyyMMdd";

	private static final Format DF = new SimpleDateFormat(FORMAT);

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

	private String prefix = null;

	private Date date = null;

	private int number = 1;

	private static Map<String, SerialUtil> map = new HashMap<String, SerialUtil>();
	
	public static void main(String [] args){
		
		System.out.println(SerialUtil.newInstance("BDCID", new Date()).toString());
		System.out.println(SerialUtil.newInstance("BDCID", new Date()).toString());
		System.out.println(SerialUtil.newInstance("BDCID", new Date()).toString());
		System.out.println(SerialUtil.newInstance("BDCID", new Date()).toString());
		
		
		System.out.println(SerialUtil.newInstance("BDID", new Date()).toString());
		System.out.println(SerialUtil.newInstance("BDID", new Date()).toString());
		System.out.println(SerialUtil.newInstance("BDID", new Date()).toString());
		System.out.println(SerialUtil.newInstance("BDID", new Date()).toString());
	}

	private SerialUtil(String prefix, Date date) {
		this.prefix = prefix;
		this.date = date;
	}

	public static SerialUtil newInstance(String prefix) {
		Date date = new Date();
		return newInstance(prefix, date);
	}

	public static SerialUtil newInstance(String prefix, Date date) {

		SerialUtil o = null;
		synchronized (lock) {

			String key = getKey(prefix, date);
			if (map.containsKey(key)) {
				o = map.get(key);
				int number = o.getNumber();
				if (number < MAX_VALUE) {
					o.setNumber(number + 1);
				} else {
					o.setNumber(1);
				}
			} else {

				o = new SerialUtil(prefix, date);
				map.put(key, o);
			}
		}
		return o;
	}

	private static String getKey(String prefix, Date date) {
		return prefix + format(date);
	}

	private static String format(Date date) {
		return DF.format(date);
	}

	public String toString() {
		prefix = "";
		return prefix + format(date) + String.format("%08d", number);
	}

	public void setNumber(int number) {
		this.number = number;
	}

	public int getNumber() {
		return number;
	}
}

转载于:https://my.oschina.net/xf1025/blog/856689