新手来求教之四_一些设计上的疑惑,该如何处理

public abstract class AbstBaseQuerySpec implements HibernateCallback,
        Serializable {
    /** 当前页码数 */
    protected Paginate paginate = new Paginate();

    /** 是否需要分页支持 */
    protected boolean paginary = true;

    /**
     * 重置查询条件
     */
    public void resetSpec() {
        paginate.reset();
        reset();
    }
    public Object doInHibernate(Session session) throws HibernateException,
            SQLException {
        return null;
    }
    protected void applyNamedParameterToQuery(Query queryObject,
            String paramName, Object value) throws HibernateException {
        if (value instanceof Collection) {
            queryObject.setParameterList(paramName, (Collection) value);
        } else if (value instanceof Object[]) {
            queryObject.setParameterList(paramName, (Object[]) value);
        } else {
            queryObject.setParameter(paramName, value);
        }
    }

    /**
     * reset spec
     */
    protected abstract void reset();

    /**
     * 执行查询后，通过此方法取得分页信息
     * 
     * @return
     */
    public Paginate getPaginate() {
        return paginate;
    }

    /**
     * @param paginate
     *            The paginate to set.
     */
    public void setPaginate(Paginate paginate) {
        this.paginate = paginate;
    }

    /**
     * @param paginary
     *            The paginary to set.
     */
    public void setPaginary(boolean paginary) {
        this.paginary = paginary;
    }
}


// 基于Hibernate查询规则限定条件
public abstract class AbstQueryStringSpec extends AbstBaseQuerySpec {
    /**   */
    private Map<String, Object> params = new HashMap<String, Object>();

    /**
     * Named hql queryName
     * 
     * @return
     */
    public abstract String queryString();

    /**
     * 
     * @param session
     * @return
     * @throws HibernateException
     * @throws SQLException
     * @see org.springframework.orm.hibernate3.HibernateCallback#doInHibernate(org.hibernate.Session)
     */
    public Object doInHibernate(Session session) throws HibernateException,
            SQLException {
        params.clear();
        Query query = session.createQuery(queryString());
        Iterator<Map.Entry<String, Object>> pIt = params.entrySet().iterator();
        while (pIt.hasNext()) {
            Map.Entry<String, Object> entry = pIt.next();
            applyNamedParameterToQuery(query, entry.getKey(), entry.getValue());
        }
        if (paginary) {
            List total = query.list();
            int totalRows = total.size();
            paginate.setTotalRow(totalRows);
            query.setFirstResult(paginate.getStartIndex());
            query.setMaxResults(paginate.getPageLine());
        }
        List result = query.list();
        return result;
    }

    /**
     * 设置Query接口命名参数
     * 
     * @param name
     * @param value
     */
    protected void setParam(String name, Object value) {
        this.params.put(name, value);
    }
}


/**
 * 功能概述：<br>
 * 机柜统计查询类
 * 
 *  以下是查询类，具体查询数据时
 * 
 */
//public class CabinetStatisticSpec extends AbstQueryStringSpec {
    /** 机房ID */
    private Integer compLocaId;
    @Override
    public String queryString() {
        // hql 查询
        StringBuffer hql = new StringBuffer(
                "select cl.name, "
                        + "sum(case when nc.useHigh=null or nc.useHigh=0 then 1 else 0 end) as unusedCabinet, "
                        + "sum(case when nc.useHigh>0 and nc.useHigh<nc.height then 1 else 0 end) as nofullCabinet, "
                        + "sum(case when nc.useHigh>=nc.height then 1 else 0 end) as fullCabinet, "
                        + "count(*) as totalCabinet "
                        + "FROM NetworkCabinets nc,ComputerLocation cl "
                        + "WHERE nc.compLocaId=cl.id ");

        if (QuerySpecUtil.valid(compLocaId)) {
            hql.append(" AND nc.compLocaId=:compLocaId ");
            this.setParam("compLocaId", compLocaId);
        }
        hql.append(" group by cl.name ");
        return hql.toString();

    @Override
    protected void reset() {
        compLocaId = null;
    }

    public Integer getCompLocaId() {
        return compLocaId;
    }

    public void setCompLocaId(Integer compLocaId) {
        this.compLocaId = compLocaId;
    }

}

spec在struts2 action中作为属性，调用service时作为参数，service中直接用DAO查询，参数就是从action中传过来的spec

我感觉这个设计还是很好的，遂给出部分代码。希望对大家有一点参考作用
















 


 



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