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.javapackage 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>