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,��? 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;
public class PaginationSupport {
public final static int PAGESIZE = 30;
private int pageSize = PAGESIZE;
private List items;
private int totalCount;
private int[] indexes = newint[0];
private int 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); }
public List getItems(){ return items; }
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 = newint[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; elseif(startIndex >= totalCount) this.startIndex = indexes[indexes.length - 1]; elseif(startIndex < 0) this.startIndex = 0; else{ this.startIndex = indexes[startIndex / pageSize]; } }
public int getNextIndex(){ int nextIndex = getStartIndex() + pageSize; if(nextIndex >= totalCount) return getStartIndex(); else return nextIndex; }
public int getPreviousIndex(){ int previousIndex = getStartIndex() - pageSize; if(previousIndex < 0) return0; else return previousIndex; }
}
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抽象业务��?
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;
public abstractclass 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); }
public Object load(final Class entity, final Serializable id){ return getHibernateTemplate().load(entity, id); }
public Object get(final Class entity, final Serializable id){ return getHibernateTemplate().get(entity, id); }
public List findAll(final Class entity){ return getHibernateTemplate().find("from " + entity.getName()); }
public List findByNamedQuery(final String namedQuery){ return getHibernateTemplate().findByNamedQuery(namedQuery); }
public List findByNamedQuery(final String query, final Object parameter){ return getHibernateTemplate().findByNamedQuery(query, parameter); }
public List findByNamedQuery(final String query, final Object[] parameters){ return getHibernateTemplate().findByNamedQuery(query, parameters); }
public List find(final String query){ return getHibernateTemplate().find(query); }
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); }
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); }
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(); } }
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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��? ps.getTotalCount()得到总结果数 ps.getStartIndex()当前分页索引 ps.getNextIndex()下一页索��? ps.getPreviousIndex()上一页索��?br />
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 * */ public class Page { /** imply if the page has previous page */ private boolean hasPrePage; /** imply if the page has next page */ private boolean hasNextPage; /** the number of every page */ private int everyPage; /** the total page number */ private int totalPage; /** the number of current page */ private int currentPage; /** the begin index of the records by the current query */ private int 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. */ public int getBeginIndex(){ return beginIndex; } /** * @param beginIndex * The beginIndex to set. */ public void setBeginIndex(int beginIndex){ this.beginIndex = beginIndex; } /** * @return * Returns the currentPage. */ public int getCurrentPage(){ return currentPage; } /** * @param currentPage * The currentPage to set. */ public void setCurrentPage(int currentPage){ this.currentPage = currentPage; } /** * @return * Returns the everyPage. */ public int getEveryPage(){ return everyPage; } /** * @param everyPage * The everyPage to set. */ public void setEveryPage(int everyPage){ this.everyPage = everyPage; } /** * @return * Returns the hasNextPage. */ public boolean getHasNextPage(){ return hasNextPage; } /** * @param hasNextPage * The hasNextPage to set. */ public void setHasNextPage(boolean hasNextPage){ this.hasNextPage = hasNextPage; } /** * @return * Returns the hasPrePage. */ public boolean getHasPrePage(){ return hasPrePage; } /** * @param hasPrePage * The hasPrePage to set. */ public void setHasPrePage(boolean hasPrePage){ this.hasPrePage = hasPrePage; } /** * @return Returns the totalPage. * */ public int getTotalPage(){ return totalPage; } /** * @param totalPage * The totalPage to set. */ public void 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 * */ public class PageUtil { private static final Log logger = LogFactory.getLog(PageUtil.class); /** * Use the origin page to create a new page * @param page * @param totalRecords * @return */ public static 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 */ public static 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); } private static int getEveryPage(int everyPage){ return everyPage == 0 ? 10 : everyPage; } private static int getCurrentPage(int currentPage){ return currentPage == 0 ? 1 : currentPage; } private static int getBeginIndex(int everyPage, int currentPage){ return(currentPage - 1) * everyPage; } private static int getTotalPage(int everyPage, int totalRecords){ int totalPage = 0; if(totalRecords % everyPage == 0) totalPage = totalRecords / everyPage; else totalPage = totalRecords / everyPage + 1 ; return totalPage; } private static boolean hasPrePage(int currentPage){ return currentPage == 1 ? false : true; } private static boolean 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��?0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 */ public class Result {
private Page page;
private List 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. */ public List getContent(){ return content; }
/** * @return Returns the page. */ public Page getPage(){ return page; }
/** * @param content * The content to set. */ public void setContent(List content){ this.content = content; }
/** * @param page * The page to set. */ public void 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 */ public interface 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 */ public class UserManagerImpl implements UserManager { private UserDAO userDAO;
/** * @param userDAO The userDAO to set. */ public void 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 ��?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 */ public interface UserDAO extends BaseDAO { public List getUserByName(String name)throws HibernateException; public int getUserCount()throws HibernateException; public List 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 */ public class UserDAOImpl extends BaseDAOHibernateImpl implements UserDAO {
/* (non-Javadoc) * @see com.adt.dao.UserDAO#getUserByName(java.lang.String) */ public List 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() */ public int 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) */ public List 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 */ public class ListUser implementsAction{
private static final Log logger = LogFactory.getLog(ListUser.class);
private UserService userService;
private Page page;
private List users;
/* * (non-Javadoc) * * @see com.opensymphony.xwork.Action#execute() */ public String 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. */ public List getUsers(){ return users; }
/** * @param page * The page to set. */ public void setPage(Page page){ this.page = page; }
/** * @param users * The users to set. */ public void setUsers(List users){ this.users = users; }
/** * @param userService * The userService to set. */ public void 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��?0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��?lt;param>的配置,还需要webwork和Spring整合的配合��?br />
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 */ public class Paginator<E> { private int count = 0; // 总记录数 private int p = 1; // 页编��?/span> private int num = 20; // 每页的记录数 private List<E> results = null; // 结果
/** * 结果总数 */ public int getCount(){ return count; }
public void setCount(int count){ this.count = count; }
/** * 本结果所在的页码,从1开��? * * @return Returns the pageNo. */ public int getP(){ return p; }
/** * if(p<=0) p=1 * * @param p */ public void setP(int p){ if(p <= 0) p = 1; this.p = p; }
/** * 每页记录数量 */ public int getNum(){ return num; }
/** * if(num<1) num=1 */ public void setNum(int num){ if(num < 1) num = 1; this.num = num; }
/** * 获得总页��? */ public int getPageNum(){ return(count - 1) / num + 1; }
/** * 获得本页的开始编号,��?(p-1)*num+1 */ public int getStart(){ return(p - 1) * num + 1; }
/** * @return Returns the results. */ public List<E> getResults(){ return results; }
public void setResults(List<E> results){ this.results = results; }
public String 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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