| Hibernate3
提供了DetachedCriteria,使得我们可以在Web层构造detachedCriteria,然后调用业务层Bean,进行动态条件查询,根
据这一功能,我设计了通用的抽象Bean基类和分页类支持,代码来自于Quake
Wang的javaeye-core包的相应类,然后又做了很多修改。 
 分页支持类:
 
 
 
												
														
																| java代码: |  
																| 
																				
 package com.javaeye.common.util;
 
 import java.util.List;
 
 publicclass PaginationSupport {
 
 publicfinalstaticint PAGESIZE = 30;
 
 privateint pageSize = PAGESIZE;
 
 privateList items;
 
 privateint totalCount;
 
 privateint[] indexes = newint[0];
 
 privateint startIndex = 0;
 
 public PaginationSupport(List items, int totalCount){
 setPageSize(PAGESIZE);
 setTotalCount(totalCount);
 setItems(items);
 setStartIndex(0);
 }
 
 public PaginationSupport(List items, int totalCount, int startIndex){
 setPageSize(PAGESIZE);
 setTotalCount(totalCount);
 setItems(items);
 setStartIndex(startIndex);
 }
 
 public PaginationSupport(List items, int totalCount, int pageSize, int startIndex){
 setPageSize(pageSize);
 setTotalCount(totalCount);
 setItems(items);
 setStartIndex(startIndex);
 }
 
 publicList getItems(){
 return items;
 }
 
 publicvoid setItems(List items){
 this.items = items;
 }
 
 publicint getPageSize(){
 return pageSize;
 }
 
 publicvoid setPageSize(int pageSize){
 this.pageSize = pageSize;
 }
 
 publicint getTotalCount(){
 return totalCount;
 }
 
 publicvoid setTotalCount(int totalCount){
 if(totalCount > 0){
 this.totalCount = totalCount;
 int count = totalCount / pageSize;
 if(totalCount % pageSize > 0)
 count++;
 indexes = newint[count];
 for(int i = 0; i < count; i++){
 indexes[i] = pageSize * i;
 }
 }else{
 this.totalCount = 0;
 }
 }
 
 publicint[] getIndexes(){
 return indexes;
 }
 
 publicvoid setIndexes(int[] indexes){
 this.indexes = indexes;
 }
 
 publicint getStartIndex(){
 return startIndex;
 }
 
 publicvoid setStartIndex(int startIndex){
 if(totalCount <= 0)
 this.startIndex = 0;
 elseif(startIndex >= totalCount)
 this.startIndex = indexes[indexes.length - 1];
 elseif(startIndex < 0)
 this.startIndex = 0;
 else{
 this.startIndex = indexes[startIndex / pageSize];
 }
 }
 
 publicint getNextIndex(){
 int nextIndex = getStartIndex() + pageSize;
 if(nextIndex >= totalCount)
 return getStartIndex();
 else
 return nextIndex;
 }
 
 publicint getPreviousIndex(){
 int previousIndex = getStartIndex() - pageSize;
 if(previousIndex < 0)
 return0;
 else
 return previousIndex;
 }
 
 }
 
 |  
 抽象业务类
 
 
												
														
																| java代码: |  
																| 
																				
 /**
 * Created on 2005-7-12
 */
 package com.javaeye.common.business;
 
 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.javaeye.common.util.PaginationSupport;
 
 publicabstractclass AbstractManager extends HibernateDaoSupport {
 
 privateboolean cacheQueries = false;
 
 privateString queryCacheRegion;
 
 publicvoid setCacheQueries(boolean cacheQueries){
 this.cacheQueries = cacheQueries;
 }
 
 publicvoid setQueryCacheRegion(String queryCacheRegion){
 this.queryCacheRegion = queryCacheRegion;
 }
 
 publicvoid save(finalObject entity){
 getHibernateTemplate().save(entity);
 }
 
 publicvoid persist(finalObject entity){
 getHibernateTemplate().save(entity);
 }
 
 publicvoid update(finalObject entity){
 getHibernateTemplate().update(entity);
 }
 
 publicvoid delete(finalObject entity){
 getHibernateTemplate().delete(entity);
 }
 
 publicObject load(finalClass entity, finalSerializable id){
 return getHibernateTemplate().load(entity, id);
 }
 
 publicObject get(finalClass entity, finalSerializable id){
 return getHibernateTemplate().get(entity, id);
 }
 
 publicList findAll(finalClass entity){
 return getHibernateTemplate().find("from " + entity.getName());
 }
 
 publicList findByNamedQuery(finalString namedQuery){
 return getHibernateTemplate().findByNamedQuery(namedQuery);
 }
 
 publicList findByNamedQuery(finalString query, finalObject parameter){
 return getHibernateTemplate().findByNamedQuery(query, parameter);
 }
 
 publicList findByNamedQuery(finalString query, finalObject[] parameters){
 return getHibernateTemplate().findByNamedQuery(query, parameters);
 }
 
 publicList find(finalString query){
 return getHibernateTemplate().find(query);
 }
 
 publicList find(finalString query, finalObject parameter){
 return getHibernateTemplate().find(query, parameter);
 }
 
 public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria){
 return findPageByCriteria(detachedCriteria, PaginationSupport.PAGESIZE, 0);
 }
 
 public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria, finalint startIndex){
 return findPageByCriteria(detachedCriteria, PaginationSupport.PAGESIZE, startIndex);
 }
 
 public PaginationSupport findPageByCriteria(final DetachedCriteria detachedCriteria, finalint pageSize,
 finalint startIndex){
 return(PaginationSupport) getHibernateTemplate().execute(new HibernateCallback(){
 publicObject 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);
 }
 
 publicList findAllByCriteria(final DetachedCriteria detachedCriteria){
 return(List) getHibernateTemplate().execute(new HibernateCallback(){
 publicObject doInHibernate(Session session)throws HibernateException {
 Criteria criteria = detachedCriteria.getExecutableCriteria(session);
 return criteria.list();
 }
 }, true);
 }
 
 publicint getCountByCriteria(final DetachedCriteria detachedCriteria){
 Integer count = (Integer) getHibernateTemplate().execute(new HibernateCallback(){
 publicObject doInHibernate(Session session)throws HibernateException {
 Criteria criteria = detachedCriteria.getExecutableCriteria(session);
 return criteria.setProjection(Projections.rowCount()).uniqueResult();
 }
 }, true);
 return count.intValue();
 }
 }
 
 
 |  
 
 用户在web层构造查询条件detachedCriteria,和可选的startIndex,调用业务bean的相应findByCriteria方法,返回一个PaginationSupport的实例ps。
 
 ps.getItems()得到已分页好的结果集
 ps.getIndexes()得到分页索引的数组
 ps.getTotalCount()得到总结果数
 ps.getStartIndex()当前分页索引
 ps.getNextIndex()下一页索引
 ps.getPreviousIndex()上一页索引
 
 
 
 
 
 
 连续看了两篇robbin有关DetachedCriteria的介绍,感觉真的不错,尤其是上面的示例代码,让我着实觉得该对我原来的分页查询做一下代码重构了。
 
 我把原本我的做法也提供出来供大家讨论吧:
 
 首先,为了实现分页查询,我封装了一个Page类:
 
 
												
														
																| java代码: |  
																| 
																				
 /*Created on 2005-4-14*/
 package org.flyware.util.page;
 
 /**
 * @author Joa
 *
 */
 publicclass Page {
 
 /** imply if the page has previous page */
 privateboolean hasPrePage;
 
 /** imply if the page has next page */
 privateboolean hasNextPage;
 
 /** the number of every page */
 privateint everyPage;
 
 /** the total page number */
 privateint totalPage;
 
 /** the number of current page */
 privateint currentPage;
 
 /** the begin index of the records by the current query */
 privateint beginIndex;
 
 
 /** The default constructor */
 public Page(){
 
 }
 
 /** construct the page by everyPage
 * @param everyPage
 * */
 public Page(int everyPage){
 this.everyPage = everyPage;
 }
 
 /** The whole constructor */
 public Page(boolean hasPrePage, boolean hasNextPage,
 int everyPage, int totalPage,
 int currentPage, int beginIndex){
 this.hasPrePage = hasPrePage;
 this.hasNextPage = hasNextPage;
 this.everyPage = everyPage;
 this.totalPage = totalPage;
 this.currentPage = currentPage;
 this.beginIndex = beginIndex;
 }
 
 /**
 * @return
 * Returns the beginIndex.
 */
 publicint getBeginIndex(){
 return beginIndex;
 }
 
 /**
 * @param beginIndex
 * The beginIndex to set.
 */
 publicvoid setBeginIndex(int beginIndex){
 this.beginIndex = beginIndex;
 }
 
 /**
 * @return
 * Returns the currentPage.
 */
 publicint getCurrentPage(){
 return currentPage;
 }
 
 /**
 * @param currentPage
 * The currentPage to set.
 */
 publicvoid setCurrentPage(int currentPage){
 this.currentPage = currentPage;
 }
 
 /**
 * @return
 * Returns the everyPage.
 */
 publicint getEveryPage(){
 return everyPage;
 }
 
 /**
 * @param everyPage
 * The everyPage to set.
 */
 publicvoid setEveryPage(int everyPage){
 this.everyPage = everyPage;
 }
 
 /**
 * @return
 * Returns the hasNextPage.
 */
 publicboolean getHasNextPage(){
 return hasNextPage;
 }
 
 /**
 * @param hasNextPage
 * The hasNextPage to set.
 */
 publicvoid setHasNextPage(boolean hasNextPage){
 this.hasNextPage = hasNextPage;
 }
 
 /**
 * @return
 * Returns the hasPrePage.
 */
 publicboolean getHasPrePage(){
 return hasPrePage;
 }
 
 /**
 * @param hasPrePage
 * The hasPrePage to set.
 */
 publicvoid setHasPrePage(boolean hasPrePage){
 this.hasPrePage = hasPrePage;
 }
 
 /**
 * @return Returns the totalPage.
 *
 */
 publicint getTotalPage(){
 return totalPage;
 }
 
 /**
 * @param totalPage
 * The totalPage to set.
 */
 publicvoid setTotalPage(int totalPage){
 this.totalPage = totalPage;
 }
 
 }
 
 
 |  
 上面的这个Page类对象只是一个完整的Page描述,接下来我写了一个PageUtil,负责对Page对象进行构造:
 
 
												
														
																| java代码: |  
																| 
																				
 /*Created on 2005-4-14*/
 package org.flyware.util.page;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 /**
 * @author Joa
 *
 */
 publicclass PageUtil {
 
 privatestaticfinal Log logger = LogFactory.getLog(PageUtil.class);
 
 /**
 * Use the origin page to create a new page
 * @param page
 * @param totalRecords
 * @return
 */
 publicstatic Page createPage(Page page, int totalRecords){
 return createPage(page.getEveryPage(), page.getCurrentPage(), totalRecords);
 }
 
 /**
 * the basic page utils not including exception handler
 * @param everyPage
 * @param currentPage
 * @param totalRecords
 * @return page
 */
 publicstatic Page createPage(int everyPage, int currentPage, int totalRecords){
 everyPage = getEveryPage(everyPage);
 currentPage = getCurrentPage(currentPage);
 int beginIndex = getBeginIndex(everyPage, currentPage);
 int totalPage = getTotalPage(everyPage, totalRecords);
 boolean hasNextPage = hasNextPage(currentPage, totalPage);
 boolean hasPrePage = hasPrePage(currentPage);
 
 returnnew Page(hasPrePage, hasNextPage,
 everyPage, totalPage,
 currentPage, beginIndex);
 }
 
 privatestaticint getEveryPage(int everyPage){
 return everyPage == 0 ? 10 : everyPage;
 }
 
 privatestaticint getCurrentPage(int currentPage){
 return currentPage == 0 ? 1 : currentPage;
 }
 
 privatestaticint getBeginIndex(int everyPage, int currentPage){
 return(currentPage - 1) * everyPage;
 }
 
 privatestaticint getTotalPage(int everyPage, int totalRecords){
 int totalPage = 0;
 
 if(totalRecords % everyPage == 0)
 totalPage = totalRecords / everyPage;
 else
 totalPage = totalRecords / everyPage + 1 ;
 
 return totalPage;
 }
 
 privatestaticboolean hasPrePage(int currentPage){
 return currentPage == 1 ? false : true;
 }
 
 privatestaticboolean hasNextPage(int currentPage, int totalPage){
 return currentPage == totalPage || totalPage == 0 ? false : true;
 }
 
 
 }
 
 
 |  
 上面的这两个对象与具体的业务逻辑无关,可以独立和抽象。
 
 面对一个具体的业务逻辑:分页查询出User,每页10个结果。具体做法如下:
 1. 编写一个通用的结果存储类Result,这个类包含一个Page对象的信息,和一个结果集List:
 
 
												
														
																| java代码: |  
																| 
																				
 /*Created on 2005-6-13*/
 package com.adt.bo;
 
 import java.util.List;
 
 import org.flyware.util.page.Page;
 
 /**
 * @author Joa
 */
 publicclass Result {
 
 private Page page;
 
 privateList content;
 
 /**
 * The default constructor
 */
 public Result(){
 super();
 }
 
 /**
 * The constructor using fields
 *
 * @param page
 * @param content
 */
 public Result(Page page, List content){
 this.page = page;
 this.content = content;
 }
 
 /**
 * @return Returns the content.
 */
 publicList getContent(){
 return content;
 }
 
 /**
 * @return Returns the page.
 */
 public Page getPage(){
 return page;
 }
 
 /**
 * @param content
 *            The content to set.
 */
 publicvoid setContent(List content){
 this.content = content;
 }
 
 /**
 * @param page
 *            The page to set.
 */
 publicvoid setPage(Page page){
 this.page = page;
 }
 }
 
 
 |  
 2. 编写业务逻辑接口,并实现它(UserManager, UserManagerImpl)
 
 
												
														
																| java代码: |  
																| 
																				
 /*Created on 2005-7-15*/
 package com.adt.service;
 
 import net.sf.hibernate.HibernateException;
 
 import org.flyware.util.page.Page;
 
 import com.adt.bo.Result;
 
 /**
 * @author Joa
 */
 publicinterface UserManager {
 
 public Result listUser(Page page)throws HibernateException;
 
 }
 
 
 |  
 
 
												
														
																| java代码: |  
																| 
																				
 /*Created on 2005-7-15*/
 package com.adt.service.impl;
 
 import java.util.List;
 
 import net.sf.hibernate.HibernateException;
 
 import org.flyware.util.page.Page;
 import org.flyware.util.page.PageUtil;
 
 import com.adt.bo.Result;
 import com.adt.dao.UserDAO;
 import com.adt.exception.ObjectNotFoundException;
 import com.adt.service.UserManager;
 
 /**
 * @author Joa
 */
 publicclass UserManagerImpl implements UserManager {
 
 private UserDAO userDAO;
 
 /**
 * @param userDAO The userDAO to set.
 */
 publicvoid setUserDAO(UserDAO userDAO){
 this.userDAO = userDAO;
 }
 
 /* (non-Javadoc)
 * @see com.adt.service.UserManager#listUser(org.flyware.util.page.Page)
 */
 public Result listUser(Page page)throws HibernateException, ObjectNotFoundException {
 int totalRecords = userDAO.getUserCount();
 if(totalRecords == 0)
 throw new ObjectNotFoundException("userNotExist");
 page = PageUtil.createPage(page, totalRecords);
 List users = userDAO.getUserByPage(page);
 returnnew Result(page, users);
 }
 
 }
 
 
 |  
 其中,UserManagerImpl中调用userDAO的方法实现对User的分页查询,接下来编写UserDAO的代码:
 3. UserDAO 和 UserDAOImpl:
 
 
												
														
																| java代码: |  
																| 
																				
 /*Created on 2005-7-15*/
 package com.adt.dao;
 
 import java.util.List;
 
 import org.flyware.util.page.Page;
 
 import net.sf.hibernate.HibernateException;
 
 /**
 * @author Joa
 */
 publicinterface UserDAO extends BaseDAO {
 
 publicList getUserByName(String name)throws HibernateException;
 
 publicint getUserCount()throws HibernateException;
 
 publicList getUserByPage(Page page)throws HibernateException;
 
 }
 
 
 |  
 
 
												
														
																| java代码: |  
																| 
																				
 /*Created on 2005-7-15*/
 package com.adt.dao.impl;
 
 import java.util.List;
 
 import org.flyware.util.page.Page;
 
 import net.sf.hibernate.HibernateException;
 import net.sf.hibernate.Query;
 
 import com.adt.dao.UserDAO;
 
 /**
 * @author Joa
 */
 publicclass UserDAOImpl extends BaseDAOHibernateImpl implements UserDAO {
 
 /* (non-Javadoc)
 * @see com.adt.dao.UserDAO#getUserByName(java.lang.String)
 */
 publicList getUserByName(String name)throws HibernateException {
 String querySentence = "FROM user in class com.adt.po.User WHERE user.name=:name";
 Query query = getSession().createQuery(querySentence);
 query.setParameter("name", name);
 return query.list();
 }
 
 /* (non-Javadoc)
 * @see com.adt.dao.UserDAO#getUserCount()
 */
 publicint getUserCount()throws HibernateException {
 int count = 0;
 String querySentence = "SELECT count(*) FROM user in class com.adt.po.User";
 Query query = getSession().createQuery(querySentence);
 count = ((Integer)query.iterate().next()).intValue();
 return count;
 }
 
 /* (non-Javadoc)
 * @see com.adt.dao.UserDAO#getUserByPage(org.flyware.util.page.Page)
 */
 publicList getUserByPage(Page page)throws HibernateException {
 String querySentence = "FROM user in class com.adt.po.User";
 Query query = getSession().createQuery(querySentence);
 query.setFirstResult(page.getBeginIndex())
 .setMaxResults(page.getEveryPage());
 return query.list();
 }
 
 }
 
 
 |  
 至此,一个完整的分页程序完成。前台的只需要调用userManager.listUser(page)即可得到一个Page对象和结果集对象的综合体,而传入的参数page对象则可以由前台传入,如果用webwork,甚至可以直接在配置文件中指定。
 
 下面给出一个webwork调用示例:
 
 
												
														
																| java代码: |  
																| 
																				
 /*Created on 2005-6-17*/
 package com.adt.action.user;
 
 import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.flyware.util.page.Page;
 
 import com.adt.bo.Result;
 import com.adt.service.UserService;
 import com.opensymphony.xwork.Action;
 
 /**
 * @author Joa
 */
 publicclass ListUser implementsAction{
 
 privatestaticfinal Log logger = LogFactory.getLog(ListUser.class);
 
 private UserService userService;
 
 private Page page;
 
 privateList users;
 
 /*
 * (non-Javadoc)
 *
 * @see com.opensymphony.xwork.Action#execute()
 */
 publicString execute()throwsException{
 Result result = userService.listUser(page);
 page = result.getPage();
 users = result.getContent();
 return SUCCESS;
 }
 
 /**
 * @return Returns the page.
 */
 public Page getPage(){
 return page;
 }
 
 /**
 * @return Returns the users.
 */
 publicList getUsers(){
 return users;
 }
 
 /**
 * @param page
 *            The page to set.
 */
 publicvoid setPage(Page page){
 this.page = page;
 }
 
 /**
 * @param users
 *            The users to set.
 */
 publicvoid setUsers(List users){
 this.users = users;
 }
 
 /**
 * @param userService
 *            The userService to set.
 */
 publicvoid setUserService(UserService userService){
 this.userService = userService;
 }
 }
 
 
 |  
 上面的代码似乎看不出什么地方设置了page的相关初值,事实上,可以通过配置文件来进行配置,例如,我想每页显示10条记录,那么只需要:
 
 
												
														
																| java代码: |  
																| 
																				
 <?xml version="1.0"?>
 <!DOCTYPE xwork PUBLIC "-//OpenSymphony Group//XWork 1.0//EN" "http://www.opensymphony.com/xwork/xwork-1.0.dtd">
 
 <xwork>
 
 <package name="user" extends="webwork-interceptors">
 
 <!-- The default interceptor stack name -->
 <default-interceptor-ref name="myDefaultWebStack"/>
 
 <action name="listUser" class="com.adt.action.user.ListUser">
 <param name="page.everyPage">10</param>
 <result name="success">/user/user_list.jsp</result>
 </action>
 
 </package>
 
 </xwork>
 
 
 
 |  
 这样就可以通过配置文件和OGNL的共同作用来对page对象设置初值了。并可以通过随意修改配置文件来修改每页需要显示的记录数。
 
 注:上面的<param>的配置,还需要webwork和Spring整合的配合。
 
 
 
 
 我写的一个用于分页的类,用了泛型了,hoho
 
 
 
												
														
																| java代码: |  
																| 
																				
 package com.intokr.util;
 
 import java.util.List;
 
 /**
 * 用于分页的类<br>
 * 可以用于传递查询的结果也可以用于传送查询的参数<br>
 *
 * @version 0.01
 * @author cheng
 */
 publicclass Paginator<E> {
 privateint count = 0; // 总记录数
 privateint p = 1; // 页编号
 privateint num = 20; // 每页的记录数
 privateList<E> results = null; // 结果
 
 /**
 * 结果总数
 */
 publicint getCount(){
 return count;
 }
 
 publicvoid setCount(int count){
 this.count = count;
 }
 
 /**
 * 本结果所在的页码,从1开始
 *
 * @return Returns the pageNo.
 */
 publicint getP(){
 return p;
 }
 
 /**
 * if(p<=0) p=1
 *
 * @param p
 */
 publicvoid setP(int p){
 if(p <= 0)
 p = 1;
 this.p = p;
 }
 
 /**
 * 每页记录数量
 */
 publicint getNum(){
 return num;
 }
 
 /**
 * if(num<1) num=1
 */
 publicvoid setNum(int num){
 if(num < 1)
 num = 1;
 this.num = num;
 }
 
 /**
 * 获得总页数
 */
 publicint getPageNum(){
 return(count - 1) / num + 1;
 }
 
 /**
 * 获得本页的开始编号,为 (p-1)*num+1
 */
 publicint getStart(){
 return(p - 1) * num + 1;
 }
 
 /**
 * @return Returns the results.
 */
 publicList<E> getResults(){
 return results;
 }
 
 publicvoid setResults(List<E> results){
 this.results = results;
 }
 
 publicString toString(){
 StringBuilder buff = new StringBuilder();
 buff.append("{");
 buff.append("count:").append(count);
 buff.append(",p:").append(p);
 buff.append(",nump:").append(num);
 buff.append(",results:").append(results);
 buff.append("}");
 return buff.toString();
 }
 
 }
 
 
 |  
 偷窥自 http://forum.javaeye.com/
 
 
 |