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使用Pager在jsp分页，利用ThreadLocal 的特性保证每个线程有唯一的分页信息，且能随时存取。

pager 的缺陷：无法使用post提交请求

1 pager.jsp

maxPageItems 用来计算页数并显示。值为page size

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
   <%@ taglib prefix="pg" uri="http://jsptags.com/tags/navigation/pager" %><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
   
         	共${pagerModel.total }条记录    	
       		
        	
        
              
     首页      
          
              
     上一页      
          
              
                   
                        
       ${pageNumber }              
                    
                        
       ${pageNumber }              
                
           
          
              
     下一页      
          
              
     尾页      
    
   

2. 列表jsp 中引用 pager.jsp

url 为点击下一页、页数、尾页等访问的链接

params为访问附带的参数，多个用逗号隔开（此参数的值为上一次请求参数的值）

3. PageModel.java 分页实体

public class PageModel {	public static final int OFFSET = 0;	public static final int PAGE_SIZE = 10;	/**	 * 总记录数	 */	private int total;	private int offset = OFFSET;	private int pageSize = PAGE_SIZE;	public PageModel() {	}	public PageModel(int offset, int pageSize) {		this.offset = offset;		this.pageSize = pageSize;	}		//省略 getter setter}

4 PagerThreadLocal.java

用 ThreadLocal 存储 PageModel

public class PagerThreadLocal{	/**	 * create the threadLocal	 */	public static ThreadLocal
   
     pagerThreadLocal = new ThreadLocal
    
     ();	/**	 * get the pageModel from the threadLocal;
     
	 * if the pageModel is null, create a new pageModel	 * @return	 */	public static PageModel getPageModel(){		return pagerThreadLocal.get() == null ? new PageModel() :  pagerThreadLocal.get();	}		/**	 * set the pageModel to the threadLocal	 * @param pageModel	 */	public static void setPageModel(PageModel pageModel){		pagerThreadLocal.set(pageModel);	}		/**	 * when the request is over, remove the pageModel from threadLocal	 */	public static void remove(){		pagerThreadLocal.remove();	}}
    
   

5，PagerInterceptor.java 拦截器 

public class PagerInterceptor extends HandlerInterceptorAdapter {	@Override	public boolean preHandle(HttpServletRequest request,			HttpServletResponse response, Object handler) throws Exception {		int offset = 0;		try {			offset = Integer.parseInt(request.getParameter("pager.offset"));		} catch (NumberFormatException e) {		}				PageModel pageModel = PagerThreadLocal.getPageModel();		pageModel.setOffset(offset);		PagerThreadLocal.setPageModel(pageModel);				return super.preHandle(request, response, handler);	}	@Override	public void postHandle(HttpServletRequest request,			HttpServletResponse response, Object handler,			ModelAndView modelAndView) throws Exception {		request.setAttribute("pagerModel", PagerThreadLocal.getPageModel());		super.postHandle(request, response, handler, modelAndView);	}	@Override	public void afterCompletion(HttpServletRequest request,			HttpServletResponse response, Object handler, Exception ex)			throws Exception {		PagerThreadLocal.remove();		super.afterCompletion(request, response, handler, ex);	}}

6. 存放HQL占位符键值对 

public class ParameterPair {		/**	 * 占位符参数的名字	 */	private String paramName;		/**	 * 占位符参数的值	 */	private Object paramValue;			public ParameterPair() {	}	public ParameterPair(String paramName, Object paramValue) {		this.paramName = paramName;		this.paramValue = paramValue;	}	//省略 getter setter}

将请求参数 放入ParameterPair List中后

7.BaseHibernateDao 中 有如下 hql 分页不分页条件查询方法

/**	 * 分页或非分页 条件查询 	 * @param hql hql语句	 * @param paramList ParameterPair List	 * @param isPaging true:分页    false:不分页	 * @return	 */	public List queryPagingData(String hql, List
   
     paramList, boolean isPaging) {		Query query = this.getSession().createQuery(hql);				//分页		if (isPaging) {			String countHql = "SELECT COUNT(*) " + hql;			Query countQuery = this.getSession().createQuery(countHql);						if (paramList != null) {				for (ParameterPair pair : paramList) {					countQuery.setParameter(pair.getParamName(), pair.getParamValue());					query.setParameter(pair.getParamName(), pair.getParamValue());				}			}						int total = Integer.parseInt(countQuery.uniqueResult().toString());						PageModel pageModel = PagerThreadLocal.getPageModel();			pageModel.setTotal(total);						query.setFirstResult(pageModel.getOffset());	//注意Hibernate分页要从开始记录的上一条记录开始取			query.setMaxResults(pageModel.getPageSize());		} else {			if (paramList != null) {				for (ParameterPair pair : paramList) {					query.setParameter(pair.getParamName(), pair.getParamValue());				}			}		}				return query.list();	}
   

简单的 分页不分页动态查询 在处理完 业务特有的 逻辑后，便可使用此通用查询方法。

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