Hibernate 分页应用

在项目中，分页是经常要用到的，详细记录Hibernate分页技术：

 

1.借用robbin的代码，稍做修改

   AbstractManager.java

package com.wygl.dao;

import java.io.Serializable;   
import java.util.List;   
  
import org.hibernate.Criteria;   
import org.hibernate.HibernateException;   
import org.hibernate.Session;   
import org.hibernate.criterion.DetachedCriteria;   
import org.hibernate.criterion.Projections;   
import org.springframework.orm.hibernate3.HibernateCallback;   
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;   
  
import com.wygl.service.*;   
  
public abstract class AbstractManager extends HibernateDaoSupport {   
  
    private boolean cacheQueries = false;   
  
    private String queryCacheRegion;   
  
    public void setCacheQueries(boolean cacheQueries) {   
        this.cacheQueries = cacheQueries;   
    }   
  
    public void setQueryCacheRegion(String queryCacheRegion) {   
        this.queryCacheRegion = queryCacheRegion;   
    }   
  
    public void save(final Object entity) {   
        getHibernateTemplate().save(entity);   
    }   
  
    public void persist(final Object entity) {   
        getHibernateTemplate().save(entity);   
    }   
  
    public void update(final Object entity) {   
        getHibernateTemplate().update(entity);   
    }   
  
    public void delete(final Object entity) {   
        getHibernateTemplate().delete(entity);   
    }   
  
    @SuppressWarnings("unchecked")
    public Object load(final Class entity, final Serializable id) {   
        return getHibernateTemplate().load(entity, id);   
    }   
  
    @SuppressWarnings("unchecked")
    public Object get(final Class entity, final Serializable id) {   
        return getHibernateTemplate().get(entity, id);   
    }   
  
    @SuppressWarnings("unchecked")
    public List findAll(final Class entity) {   
        return getHibernateTemplate().find("from " + entity.getName());   
    }   
  
    @SuppressWarnings("unchecked")
    public List findByNamedQuery(final String namedQuery) {   
        return getHibernateTemplate().findByNamedQuery(namedQuery);   
    }   
  
    @SuppressWarnings("unchecked")
    public List findByNamedQuery(final String query, final Object parameter) {   
        return getHibernateTemplate().findByNamedQuery(query, parameter);   
    }   
  
    @SuppressWarnings("unchecked")
    public List findByNamedQuery(final String query, final Object[] parameters) {   
        return getHibernateTemplate().findByNamedQuery(query, parameters);   
    }   
  
    @SuppressWarnings("unchecked")
    public List find(final String query) {   
        return getHibernateTemplate().find(query);   
    }   
  
    @SuppressWarnings("unchecked")
    public List find(final String query, final Object parameter) {   
        return getHibernateTemplate().find(query, parameter);   
    }   
  
    public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria) {   
        return findPageByCriteria(detachedCriteria, PaginationSupport.PAGESIZE, 0);   
    }   
  
    public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria, final int startIndex) {   
        return findPageByCriteria(detachedCriteria, PaginationSupport.PAGESIZE, startIndex);   
    }   
  
    @SuppressWarnings("unchecked")
    public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria, final int pageSize,   
            final int startIndex) {   
        return (PaginationSupport) getHibernateTemplate().execute(new HibernateCallback() {   
            public Object doInHibernate(Session session) throws HibernateException {   
                Criteria criteria = detachedCriteria.getExecutableCriteria(session);   
                int totalCount = ((Integer) criteria.setProjection(Projections.rowCount()).uniqueResult()).intValue();   
                criteria.setProjection(null);   
                List items = criteria.setFirstResult(startIndex).setMaxResults(pageSize).list();   
                PaginationSupport ps = new PaginationSupport(items, totalCount, pageSize, startIndex);   
                return ps;   
            }   
        }, true);   
    }   
  
    @SuppressWarnings("unchecked")
    public List findAllByCriteria(final DetachedCriteria detachedCriteria) {   
        return (List) getHibernateTemplate().execute(new HibernateCallback() {   
            public Object doInHibernate(Session session) throws HibernateException {   
                Criteria criteria = detachedCriteria.getExecutableCriteria(session);   
                return criteria.list();   
            }   
        }, true);   
    }   
  
    public int getCountByCriteria(final DetachedCriteria detachedCriteria) {   
        Integer count = (Integer) getHibernateTemplate().execute(new HibernateCallback() {   
            public Object doInHibernate(Session session) throws HibernateException {   
                Criteria criteria = detachedCriteria.getExecutableCriteria(session);   
                return criteria.setProjection(Projections.rowCount()).uniqueResult();   
            }   
        }, true);   
        return count.intValue();   
    }   
}  

 

 

PaginationSupport.java 

package com.wygl.service;

import java.util.List;   

public class PaginationSupport {   
  
	//每页数量
    public final static int PAGESIZE = 30;   
  
    private int pageSize = PAGESIZE;   
  
    //查出的记录
    @SuppressWarnings("unchecked")
	private List items;   
  
    //记录总数
    private int totalCount;   
  
    private int[] indexes = new int[0];   
  
    //开始索引号
    private int startIndex = 0;   
    
    //当前页数
    private int page = 0;
    
    public void setPage(int page){
    	this.page = page;
    }
    
    public int getPage(){
    	return startIndex / pageSize + 1;
    }
    
    //总页数
    private int totalPage = 0;
    
    public void setTotalPage(int totalPage){
    	this.totalPage = totalPage;
    }
    
    public int getTotalPage(){
    	int count = totalCount / pageSize;   
        if (totalCount % pageSize > 0)   
            count++;   
        return count;
    }
    
    @SuppressWarnings("unchecked")
    public PaginationSupport(List items, int totalCount) {   
        setPageSize(PAGESIZE);   
                setTotalCount(totalCount);   
        setItems(items);           
        setStartIndex(0);   
    }   
  
    @SuppressWarnings("unchecked")
    public PaginationSupport(List items, int totalCount, int startIndex) {   
                setPageSize(PAGESIZE);   
        setTotalCount(totalCount);   
        setItems(items);           
        setStartIndex(startIndex);   
    }   
  
    @SuppressWarnings("unchecked")
    public PaginationSupport(List items, int totalCount, int pageSize, int startIndex) {   
                setPageSize(pageSize);   
        setTotalCount(totalCount);   
        setItems(items);   
        setStartIndex(startIndex);   
    }   
  
    @SuppressWarnings("unchecked")
    public List getItems() {   
        return items;   
    }   
  
    @SuppressWarnings("unchecked")
    public void setItems(List items) {   
        this.items = items;   
    }   
  
    public int getPageSize() {   
        return pageSize;   
    }   
  
    public void setPageSize(int pageSize) {   
        this.pageSize = pageSize;   
    }   
  
    public int getTotalCount() {   
        return totalCount;   
    }   
  
    public void setTotalCount(int totalCount) {   
        if (totalCount > 0) {   
            this.totalCount = totalCount;   
            int count = totalCount / pageSize;   
            if (totalCount % pageSize > 0)   
                count++;   
            indexes = new int[count];   
            for (int i = 0; i < count; i++) {   
                indexes[i] = pageSize * i;   
            }   
        } else {   
            this.totalCount = 0;   
        }   
    }   
  
    public int[] getIndexes() {   
        return indexes;   
    }   
  
    public void setIndexes(int[] indexes) {   
        this.indexes = indexes;   
    }   
  
    public int getStartIndex() {   
        return startIndex;   
    }   
  
    public void setStartIndex(int startIndex) {   
        if (totalCount <= 0)   
            this.startIndex = 0;   
        else if (startIndex >= totalCount)   
            this.startIndex = indexes[indexes.length - 1];   
        else if (startIndex < 0)   
            this.startIndex = 0;   
        else {   
            this.startIndex = indexes[startIndex / pageSize];   
        }   
    }   
  
    public int getNextIndex() {   
        int nextIndex = getStartIndex() + pageSize;   
        if (nextIndex >= totalCount)   
            return -1;   
        else  
            return nextIndex;   
    }   
  
    public int getPreviousIndex() {   
        int previousIndex = getStartIndex() - pageSize;   
        if (previousIndex < 0)   
            return -1;   
        else  
            return previousIndex;   
    }   
  
}  

 

 

写好2个类后，下来就是应用

 

2. Action中这样

UserManagerAction.java

	/** 
	 * DD注释： 显示所有用户
	 * 分页显示！
	 * @param mapping
	 * @param form
	 * @param request
	 * @param response
	 * @return
	 */
	public ActionForward doShowUser(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response){
		int startIndex;    //每页开始索引号
		int pageSize = 1;  //每页记录数
		//获取要访问的页数，第一次访问第一页
		String strPage = request.getParameter("page");
		if(strPage==""||strPage==null){
			startIndex = 0;
		}else{
			startIndex = Integer.parseInt(strPage);
		}
		//查找并返回PaginationSupport类型ps，将ps抛到web层
		PaginationSupport ps = userService.findUser(pageSize,startIndex);
		request.setAttribute("ps", ps);
		System.out.println("2");
		return mapping.findForward("showUser");
	}

 

UserService.java

	/**
	 * 查找所有用户，分页！
	 * @param pageSize 每页记录数
	 * @param startIndex 开始索引号
	 * @return
	 */
	public PaginationSupport findUser(int pageSize,int startIndex){
		//构造DetachedCriteria动态查询条件
		DetachedCriteria detachedCriteria = DetachedCriteria.forClass(User.class);
		return userDAO.findPageByCriteria(detachedCriteria, pageSize, startIndex);
	}
	

 

3. 在页面这样应用

showUser.jsp

		<c:if test="${ps.page-1 !=0 }">
			<a href="userManager.do?command=showUser&page=0">首页</a>
		</c:if>
		<c:if test="${ps.previousIndex != -1 }">
			<a href="userManager.do?command=showUser&page=${ps.previousIndex }">上一页</a>
		</c:if>
		共查到${ps.totalCount }个用户，共${ps.totalPage }页 第${ps.page }页
		<c:if test="${ps.nextIndex != -1}">
			<a href="userManager.do?command=showUser&page=${ps.nextIndex }">下一页</a>
		</c:if>
		<c:if test="${ps.page != ps.totalPage }">
			<a href="userManager.do?command=showUser&page=${ps.totalPage -1 }">末页</a>
		</c:if>
		

评论

4 楼 phenom 2008-11-01  

浪费了你的资源，把情况说明白点。开始是这样的:
输出用户
9* zxcvzxc* 985211* [e-mail]
4* wsh* 985211* [e-mail]
1* wrfwsh* 985211* [e-mail]
struts 输出页码
第[0]页 第[1]页 第[2]页 第[3]页
totalCount:11
startIndex:0
点第二页是这样的：
输出用户
2* archko* 985211* [e-mail]
5* arch* 985211* [e-mail]
10* aftwy* 985211* [e-mail]
struts 输出页码

totalCount:0
startIndex:0

3 楼 phenom 2008-11-01  

对了，把你在DAO里的实现方法放在BaseDAOHibernate里

2 楼 phenom 2008-11-01  

我觉得不是这样用的、定义这样一个父类
public class BaseDAOHibernate extends HibernateDaoSupport implements Dao{}
子类：public class UserDaoHibernate extends BaseDAOHibernate implements UserDao{}
子类的接口：public interface UserDao extends Dao{
public PaginationSupport findPageByCriteria(
            final DetachedCriteria detachedCriteria);
    public PaginationSupport findPageByCriteria(
            final DetachedCriteria detachedCriteria,final int startIndex);
    public PaginationSupport findPageByCriteria(
            final DetachedCriteria detachedCriteria,final int pageSize,
            final int startIndex);
}
这样就行了。因为它没有依赖任何的DAO类。查询的DetachedCriteria 也是外面构造的。既然是复用，当然不能只用一次了。只要DAO实现类继承了BaseDaoHibernate就有 了这个方法，在其接口上定义就行了？ 我是这样就可以成功的。其它代码不变。
有一个问题：
我直接抄它的PanigationSUpport类，没有改变，然后action是：
{
int pageSize=3;
		int startIndex;
		String strPage=request.getParameter("startIndex");
		if(strPage==""||strPage==null){
			startIndex = 0;
		}else{
			startIndex = Integer.parseInt(strPage);
		}
PaginationSupport ps=mgr.findUserByCriteria(pageSize,startIndex);
		System.out.println("每页大小"+ps.getPageSize());
		System.out.println("开始索引"+ps.getStartIndex());
		System.out.println("数据总数"+ps.getTotalCount());
		System.out.println("索引数组长度"+ps.getIndexes().length);
		request.setAttribute("ps",ps);
		request.setAttribute("comments",ps.getItems());
		request.setAttribute("indes",ps.getIndexes());
		request.setAttribute("totalCount",ps.getTotalCount());
		request.setAttribute("startIndex",ps.getStartIndex());
		return mapping.findForward("viewAllComments");

}
打印来的只有startIndex为0时才有 数据：：
每页大小3
开始索引0
数据总数11
索引数组长度4
而点击第二页或是其它的话：Hibernate: select this_.id as id0_1_, this_.username as username0_1_, this_.password as password0_1_, this_.email as email0_1_, picture2_.id as id4_0_, picture2_.pname as pname4_0_, picture2_.premark as premark4_0_, picture2_.pcontent as pcontent4_0_, picture2_.userid as userid4_0_ from wrf.bloguser this_ left outer join wrf.blogpicture picture2_ on this_.id=picture2_.id order by this_.username desc limit ?, ?
Hibernate: select count(*) as y0_ from wrf.bloguser this_ order by this_.username desc limit ?, ?
每页大小3
开始索引0
数据总数0
索引数组长度0
JSP页面是这样的。：：只有页码。其它略。
<logic:iterate id="item" name="indes" indexId="index">
			<a href="viewAllComments.do?startIndex=<bean:write name="item" />">
			第[<bean:write name="index" />]页</a>
		</logic:iterate>
点第二页，出现的是第二页的内容，但上面打印出来 的结果却不正确的。而且第二页就没有了页码了。都显示为0。哪里出错了？请指教。

1 楼 wjhlangzi 2008-10-16  

分页是实现了。中间少点数字。。。
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