hibernate 3 ID策略生成器自定义,可用于注释 - 规则: 九位业务编号 + 六位日期 + 六位自增长序列

/**
*hibernate ID策略生成器 自定义 -  规则: 业务编号 + 日期 + 六位自增长序列
*/
public class MyKeyGenerator implements IdentifierGenerator, Configurable {

    private static final Log log = LogFactory.getLog(MyKeyGenerator.class);

    private long next;

    private String sql;
    private String table;
    private String column;
    private String schema;

   
    public synchronized Serializable generate(SessionImplementor session,
            Object object) throws HibernateException {
        SimpleDateFormat f = new SimpleDateFormat("yyMMdd");
        String preDate = f.format(new Date());
        LogAction logaction = new LogAction();
        // String bh = logaction.getBh();
        String bh = "123456789";
        return bh + preDate + getNext(session, bh,table);

    }

    public void configure(org.hibernate.type.Type type, Properties params,
            Dialect d) throws MappingException {
        table = params.getProperty("table");
        if (table == null)
            table = params.getProperty(PersistentIdentifierGenerator.TABLE);
        column = params.getProperty("column");
        if (column == null)
            column = params.getProperty(PersistentIdentifierGenerator.PK);
        schema = params.getProperty(PersistentIdentifierGenerator.SCHEMA);

    }
    /**
     * 得到当前表ID的最后六位的最大数
     *
     * @param session
     * @param jsbh
     * @return
     */
    private String getNext(SessionImplementor session, String bh,String table) {
        sql = "select  max(substr("+column+",16)) from "+(schema == null ? table : schema + '.' + table)+" where substr("+column+",10,6) = to_char(sysdate,'yyMMdd') and substr("+column+",0,9) = '" + bh + "' and  length("+column+")=21 ";
        log.info("fetching initial value: " + sql);
       
        try {
            PreparedStatement st = session
                    .getBatcher()
                    .prepareSelectStatement(
                            sql);
            try {
                ResultSet rs = st.executeQuery();
                try {
                    if (rs.next()) {
                        next = rs.getLong(1) + 1;
                        if (rs.wasNull())
                            next = 1;
                    } else {
                        next = 1;
                    }
                    sql = null;
                    log.debug("first free id: " + next);
                } finally {
                    rs.close();
                }
            } finally {
                session.getBatcher().closeStatement(st);
            }
            return toString(6, next);
        } catch (SQLException sqle) {
            throw JDBCExceptionHelper.convert(session.getFactory()
                    .getSQLExceptionConverter(), sqle,
                    "could not fetch initial value for increment generator",
                    sql);
        }
    }

    /**
     * 格式化数字不足补齐
     *
     * @param num
     * @param value
     * @return
     */
    public static String toString(int num, long value) {
        String result = (new Long(value)).toString();
        while (num > result.length()) {
            result = "0" + result;
        }
        return result;
    }



JAVA中注解使用方法:



@Id @GeneratedValue(generator="custom-id")
@GenericGenerator(name="custom-id", strategy = "javacommon.base.AwdKeyGenerator")
@Column(name = "ID", unique = true, nullable = false, insertable = true, updatable = true, length = 21)
public java.lang.String getId() {
  return this.id;
}

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1 楼 lvshuding 2011-08-05  

这样每次都从数据库中读，录入数据库频繁的时候效率是不是会低呀