模板方法模式 生成唯一编号

模板抽象类

/** * 编码生成器 */public abstract class AbstractNumberGenerator {    private int leastSerialNoLength = 6;    /**     * 生成编码     * @return     */    public String generateNumber() throws Exception {        return new StringBuilder().append(getPrefix()).append(getBusinessCode()).append(getWrapperSerialNo()).toString();    }    /**     * 前缀     * @return     */    public abstract String getPrefix();    /**     * 业务码     * @return     */    public abstract String getBusinessCode();    /**     * 顺序号     * @return     */    public abstract int getSerialNo() throws Exception ;    /**     * 顺序号最少位数     * @param length     */    protected void setLeastSerialNo(int length){        this.leastSerialNoLength = length;    }    /**     * 顺序号不足补位     * @return     */    protected String getWrapperSerialNo() throws Exception {        String format = "%0"+ leastSerialNoLength +"d";        return String.format(format, getSerialNo());    }}

数据库实现顺序号

/** * 通过数据库的索引机制，建表生成相关数据 */public class CustomerNumberCounterGenerator extends AbstractNumberGenerator {    private static final Logger LOGGER = LoggerFactory.getLogger(CustomerNumberCounterGenerator.class);    @Override    public String getPrefix() {        return "K";    }    @Override    public String getBusinessCode() {        return DateUtils.format(new Date(), "yyMMdd");    }    /**     * 获取顺序号。注：数据库建立的唯一索引机制，获取多并发的情况会报错，因此尝试第二次获取。     * @return     * @throws Exception     */    @Override    public int getSerialNo() throws Exception {        int serialNo = Integer.MIN_VALUE;        try {            serialNo = getCustomSerialNo();        } catch (Exception e) {            try {                serialNo = getCustomSerialNo();            } catch (Exception e1) {                throw new Exception("getSerialNo is failed.", e1);            }        }        return serialNo;    }    public int getCustomSerialNo() throws Exception {        String prefix = getPrefix();        String businessCode = getBusinessCode();        CustomerNumberCounter numberCounter = CustomerNumberCounter.findFirst(CustomerNumberCounter.class, "prefix=? and timeCode=?", new Object[]{prefix, businessCode});        if (null == numberCounter){            numberCounter = new CustomerNumberCounter();            numberCounter.setPrefix(prefix);            numberCounter.setTimeCode(businessCode);            numberCounter.setSerialNo(1);            numberCounter.create();            return 1;        }        try {            BaseDomain.beginTransaction(CustomerNumberCounter.class);            int execute = BaseDomain.execute(BaseDomain.class, "update t_customer_number_counter set serialNo = serialNo+1 where id = ?", new Object[]{numberCounter.getId()});            if (execute != 1)                throw new IllegalAccessException("更新计数器报错");            return CustomerNumberCounter.find(CustomerNumberCounter.class, numberCounter.getId()).getSerialNo();        }catch (Exception e){            BaseDomain.rollback(CustomerNumberCounter.class);            if (LOGGER.isErrorEnabled())                LOGGER.error("to generate customer number occur error.", e);        }finally {            if (BaseDomain.getCurrentTransaction(CustomerNumberCounter.class) != null)                BaseDomain.commit(CustomerNumberCounter.class);        }        throw new IllegalAccessException("生成客户编码失败");    }}