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:
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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; }
}
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抽象业务类
java代码:
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/** * 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(); } }
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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:
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/*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; } }
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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:
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/*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; }
}
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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:
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/*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; } }
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2. 编写业务逻辑接口,并实现它(UserManager, UserManagerImpl)
java代码:
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/*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;
}
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java代码:
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/*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); }
}
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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:
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/*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;
}
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java代码:
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/*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(); }
}
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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:
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/*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; } }
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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:
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<?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>
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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:
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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(); }
}
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偷窥自 http://forum.javaeye.com/
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