懒人的分页实现（基于Hibernate）

前几天做页面，发现有大量的分页查询页面要做，而且都是基于单表的，一开始想，用Criteria的example查询轻松啊，可是实现的时候遇到一个问题，花了一上午没搞定，再加之项目进度比较急，就想着用反射来取查询VO里得值来拼装HQL，忙乎了2个小时，做出个雏形暂时先用着，今天回头看到这个实现，感到还有一些地方可以改进，先把最初版本放上来，作为一个留念，也暂且作为我的JAVAEYE的懒人BLOG的开粪堆之做吧。

所有QueryVO继承BaseVO

public abstract class BaseVO {
	public static final String ASC = "asc";
	public static final String DESC = "desc";
	private int pageNo = 1;
	private String pageOrder = DESC;
	private boolean fuzzyQuery = true;
	private int resultsPerPage = Constants.PAGE_SIZE;
	private int pagePerGroup = Constants.PAGE_GROUP_SIZE;
	private String orderBy = "id";

        public String getOrderBy() {
		return orderBy;
	}

	public void setOrderBy(String orderBy) {
		this.orderBy = orderBy;
	}
        ....

public class User extends BaseVO implements java.io.Serializable {

	/**
	 * 
	 */
	private static final long serialVersionUID = -8138345689576402414L;

	private Integer id;

	private String username;

	private String password;

	private String email;

	private String address;

	private String zip;

	private String mobilenum;

	private String tel;

        ......

DAO实现

public class BaseDAO extends HibernateDaoSupport {
	@SuppressWarnings( { "static-access", "unchecked" })
	public Page findPageByEntityQuery(final BaseVO entity) throws Exception {
		final int pageNo = entity.getPageNo();
		final int maxResults = entity.getResultsPerPage();
		final int pagePerGroup = entity.getPagePerGroup();

		HQLFittingShop hQLFittingShop = HQLFittingShop.getInstance(entity);

		final String _finalHql = hQLFittingShop.getHql();
		final String _finalCountHql = hQLFittingShop.getCounthql();
		final Object[] _finalValues = hQLFittingShop.getPram();

		Page resultPage = (Page) getHibernateTemplate().execute(
				(new HibernateCallback() {
					public Object doInHibernate(Session session) {
						final String finalHql = _finalHql;
						final String finalCountHql = _finalCountHql;
						final Object[] finalValues = _finalValues;
						Query query = session.createQuery(finalHql);
						Query countQuery = session.createQuery(finalCountHql);
						for (int i = 0; i < finalValues.length; i++) {
							Object tempVal = finalValues[i];
							query.setParameter(i, tempVal);
							countQuery.setParameter(i, tempVal);
						}
						int totalRecord = 0;
						totalRecord = ((Integer) countQuery.uniqueResult())
								.intValue();
						Pager pager = new QueryPager(query);
						return pager.getPage(maxResults, pageNo, pagePerGroup,
								totalRecord);

					}
				}));
		return resultPage;
	}
}
}

HQLFittingShop实现

public class HQLFittingShop {
	private final String hql;

	private final Object[] pram;

	private final String counthql;

	protected HQLFittingShop(final String finalHql, final Object[] finalPram,
			final String finalCountHql) {
		super();
		this.hql = finalHql;
		this.pram = finalPram;
		this.counthql = finalCountHql;
	}

	@SuppressWarnings( { "static-access", "unchecked" })
	public static HQLFittingShop getInstance(BaseVO entity)
			throws IllegalAccessException, InvocationTargetException,
			NoSuchMethodException, InstantiationException,
			ClassNotFoundException {
		String pageOrder = entity.getPageOrder();
		String orderBy = entity.getOrderBy();
		boolean fuzzyQuery = entity.isFuzzyQuery();
		String hql = "from " + entity.getClass().getName() + " a where 1=1 ";
		List valueList = new ArrayList();
		PropertyUtils pu = new PropertyUtils();
		PropertyDescriptor[] pd = pu.getPropertyDescriptors(entity.getClass());
		BeanUtils bu = new BeanUtils();
		PropertyUtils superpu = new PropertyUtils();
		PropertyDescriptor[] superpd = superpu
				.getPropertyDescriptors(BaseVO.class);

		for (int i = 0; i < pd.length; i++) {
			if (bu.getProperty(entity, pd[i].getName()) != null) {
				boolean hasThisProprty = false;
				for (int j = 0; j < superpd.length; j++) {
					if (superpd[j].getName().equals(pd[i].getName())) {
						hasThisProprty = true;
						break;
					}
				}
				if (!hasThisProprty) {
					if (fuzzyQuery
							&& "java.lang.String".equals(pd[i]
									.getPropertyType().getName())) {
						hql += "and a." + pd[i].getName() + " like ? ";
						valueList.add("%"
								+ bu.getProperty(entity, pd[i].getName())
										.trim() + "%");
					} else {
						if (!("id".equals(pd[i].getName()) && "0".equals(bu
								.getProperty(entity, pd[i].getName())))) {
							hql += "and a." + pd[i].getName() + " = ? ";
							Object obj = ConstructorUtils.invokeConstructor(
									Class.forName(pd[i].getPropertyType()
											.getName()), bu.getProperty(entity,
											pd[i].getName()));
							valueList.add(obj);
						}
					}
				}
			}
		}

		hql += "order by a." + orderBy + " " + pageOrder;

		Object[] values = new Object[valueList.size()];
		for (int j = 0; j < values.length; j++) {
			values[j] = valueList.get(j);
		}

		final String finalHql = hql;
		final Object[] finalPram = values;
		return new HQLFittingShop(finalHql, finalPram, "select count(a.id) "
				+ hql);
	}

	public String getHql() {
		return hql;
	}

	public Object[] getPram() {
		return pram;
	}

	public String getCounthql() {
		return counthql;
	}

}

Pager实现

public class QueryPager implements Pager {

	private final Query query;

	public QueryPager(final Query query) {
		this.query = query;
	}

	public Page getPage(final int maxResults, final int pageNumber, final int pagePerGroup,final int totalPageNumber) throws HibernateException {
		query.setFirstResult((pageNumber-1)*maxResults);
		query.setMaxResults(maxResults);
		List results = query.list();
		Page pageImpl = new PageImpl(results, pageNumber, maxResults,pagePerGroup,totalPageNumber);
		return pageImpl;

	}

}

Page实现

public class PageImpl implements Page {

	private final List results;
	private final int pageNumber;
	private final int groupNumber;
	private final int resultsPerPage;
	@Deprecated
	private final int pageGroupNumber;
	private final boolean last;
	private final boolean first;
	private final boolean lastGroup;
	private final boolean firstGroup;
	private final int pagePerGroup;
	private final int[] pageGroup;
	private final int lastGroupNumber;
	private final int firstGroupNumber = 1;
	private final int lastGroupPageNumber;
	private final int firstGroupPageNumber = 1;
	private final int lastPageNumber;
	private final int firstPageNumber = 1;
	private final int totalPageNumber;
	private final int totalResultsNumber;
	private final int beforeGroupPageNumber;
	private final int afterGroupPageNumber;
	
	public PageImpl(final List results, final int pageNumber, final int resultsPerPage, final int pagePerGroup,final int totalResultsNumber) {
		super();
		this.results = results;
		this.pageNumber = pageNumber;
		this.resultsPerPage = resultsPerPage;
		this.pageGroupNumber = pagePerGroup;
		this.totalResultsNumber = totalResultsNumber;
		if(0 == totalResultsNumber % resultsPerPage){
			this.totalPageNumber = totalResultsNumber/resultsPerPage;
		}else{
			this.totalPageNumber = totalResultsNumber/resultsPerPage + 1;
		}
		this.pagePerGroup = pagePerGroup;
		if(pageNumber * resultsPerPage >= totalPageNumber){
			this.last = true;
		}else{
			this.last = false;
		}
		if(pageNumber == 1){
			this.first = true;
		}else{
			this.first = false;
		}
		if(pageNumber <= pagePerGroup){
			this.firstGroup = true;
		}else{
			this.firstGroup = false;
		}
		if(0 == totalPageNumber % pagePerGroup){
			this.lastGroupNumber = totalPageNumber/pagePerGroup;
			this.lastGroupPageNumber = lastGroupNumber*pagePerGroup;
		}else{
			this.lastGroupNumber = totalPageNumber/pagePerGroup + 1;
			this.lastGroupPageNumber = (lastGroupNumber-1)*(pagePerGroup) + 1;
		}
		if(0 == pageNumber % pagePerGroup){
			if(pageNumber/pagePerGroup - 1 == lastGroupNumber - 1){
				this.lastGroup = true;
			}else{
				this.lastGroup = false;
			}
		}else{
			if(pageNumber/pagePerGroup == lastGroupNumber - 1){
				this.lastGroup = true;
			}else{
				this.lastGroup = false;
			}
		}
		if(0 == pageNumber % pagePerGroup){
			this.groupNumber = pageNumber/pagePerGroup;
		}else{
			this.groupNumber = pageNumber/pagePerGroup + 1;
		}
		if(lastGroup){
			pageGroup = new int[totalPageNumber % pagePerGroup];
			int allReNo = this.totalPageNumber;
			for(int i=pageGroup.length;i>0;i--){
				pageGroup[i-1] = allReNo--;
			}
		}else{
			pageGroup = new int[pagePerGroup];
			for(int i=0;i<pagePerGroup;i++){
				pageGroup[i] = (groupNumber-1)*pagePerGroup + 1 + i;
			}
		}
		this.lastPageNumber = totalPageNumber;
		if(this.firstGroup){
			this.beforeGroupPageNumber = 1;
		}else{
			this.beforeGroupPageNumber = (this.groupNumber-1)*this.pagePerGroup - (this.pagePerGroup-1);
		}
		if(this.lastGroup){
			this.afterGroupPageNumber = this.lastGroupPageNumber;
		}else{
			this.afterGroupPageNumber = (this.groupNumber+1)*this.pagePerGroup - (this.pagePerGroup-1);
		}
	}
	
	public int getAfterGroupPageNumber() {
		return afterGroupPageNumber;
	}

	public int getBeforeGroupPageNumber() {
		return beforeGroupPageNumber;
	}

	public int getGroupNumber() {
		return groupNumber;
	}

	public int getPagePerGroup() {
		return pagePerGroup;
	}

	public int getTotalResultsNumber() {
		return totalResultsNumber;
	}

	public int getFirstPageNumber() {
		return firstPageNumber;
	}

	public int getLastPageNumber() {
		return lastPageNumber;
	}

	public int getLastGroupPageNumber() {
		return lastGroupPageNumber;
	}

	public int getFirstGroupPageNumber() {
		return firstGroupPageNumber;
	}

	public int[] getPageGroup() {
		return pageGroup;
	}

	public int getResultsPerPage() {
		return resultsPerPage;
	}

	public boolean isFirst() {
		return first;
	}

	public boolean isFirstGroup() {
		return firstGroup;
	}

	public boolean isLast() {
		return last;
	}

	public boolean isLastGroup() {
		return lastGroup;
	}

	public int getPageGroupNumber() {
		return pageGroupNumber;
	}

	public int getPageNumber() {
		return pageNumber;
	}

	public List getResults() {
		return results;
	}

	public int getTotalPageNumber() {
		return totalPageNumber;
	}

	public int getFirstGroupNumber() {
		return firstGroupNumber;
	}

	public int getLastGroupNumber() {
		return lastGroupNumber;
	}
	
}

页面上的处理

		<script language="javascript">
		function initial(init){
		var pageno = document.getElementById('trresearch.pageNo');
		if (pageno) {
			pageno.value = init;
		};
		document.form.submit();
		}
		</script>
		
		<html:hidden property="pageNo"/>
		<html:hidden property="pageOrder"/>
		<html:hidden property="fuzzyQuery"/>
		
<a href="javaScript:initial('1')">第一页</a> 
<a href="javaScript:initial('${page.beforeGroupPageNumber }')">前一组</a> 
                
                
<c:forEach items="${page.pageGroup}" var="pageNo">
<c:if test="${pageNo eq page.pageNumber}">
<span class="当前页">
<a href="javaScript:initial('${pageNo}')">${pageNo}</a>
</span>
</c:if>
<c:if test="${pageNo ne page.pageNumber}">
<a href="javaScript:initial('${pageNo}')">${pageNo}</a>
</c:if>
</c:forEach>
                
<a href="javaScript:initial('${page.afterGroupPageNumber }')">后一组</a> 
<a href="javaScript:initial('${page.lastPageNumber }')">最后页</a>