Displaytag1.1支持在外部实现大数据量分页。主要有两种方式实现：

Displaytag 1.1 offers two alternative ways for working with partial lists:

  • the first one uses the valuelist pattern, and requires that the object that you give to displaytag implements the org.displaytag.pagination.PaginatedList interface. You can pass this object to displaytag as an usual list, and it will extract paging and sorting information from it. This way is more recommended if you have to build your backend layer and you can easily follow this pattern.
  • a second way, recommended if you only have to use partial list for few tables that show a performance problem using full lists, is passing all the needed parameters as separate tag attributes (recors to be shown, page number, total number of records...)

其中第二种方式看起来较为简单，只需在<displaytag>中增加两个属性：partialList="true"size="resultSize"即可，但是在使用发现这种方式由于是在原来内存分页的基础上修改的，所以还是存在一些Bug（比如：分页导航的值不会变......）

所以这里介绍Displaytag推荐的第一种方式，即：
实现org.displaytag.pagination.PaginatedListorg.displaytag.pagination.PaginatedList接口。

实现PaginatedList接口：

import  java.util.List;

 import  org.displaytag.pagination.PaginatedList;
 import  org.displaytag.properties.SortOrderEnum;

 /**
 * 分页列表
 * 
 *  @author  John.Zhu
 * 
  */
public   class  PageList  implements  PaginatedList  {
     /**
     * 每页的列表
      */
     private  List list;

     /**
     * 当前页码
      */
     private   int  pageNumber  =   1 ;

     /**
     * 每页记录数 page size
      */
     private   int  objectsPerPage  =   15 ;

     /**
     * 总记录数
      */
     private   int  fullListSize  =   0 ;

     private  String sortCriterion;

     private  SortOrderEnum sortDirection;

     private  String searchId;

     public  List getList()  {
         return  list;
    }

     public   void  setList(List list)  {
         this .list  =  list;
    }

     public   int  getPageNumber()  {
         return  pageNumber;
    }

     public   void  setPageNumber( int  pageNumber)  {
         this .pageNumber  =  pageNumber;
    }

     public   int  getObjectsPerPage()  {
         return  objectsPerPage;
    }

     public   void  setObjectsPerPage( int  objectsPerPage)  {
         this .objectsPerPage  =  objectsPerPage;
    }

     public   int  getFullListSize()  {
         return  fullListSize;
    }

     public   void  setFullListSize( int  fullListSize)  {
         this .fullListSize  =  fullListSize;
    }

     public  String getSortCriterion()  {
         return  sortCriterion;
    }

     public   void  setSortCriterion(String sortCriterion)  {
         this .sortCriterion  =  sortCriterion;
    }

     public  SortOrderEnum getSortDirection()  {
         return  sortDirection;
    }

     public   void  setSortDirection(SortOrderEnum sortDirection)  {
         this .sortDirection  =  sortDirection;
    }

     public  String getSearchId()  {
         return  searchId;
    }

     public   void  setSearchId(String searchId)  {
         this .searchId  =  searchId;
    }

}

Contoller：
/**
     * 分页查询
     * 
     *  @param  request
     *  @param  response
     *  @return
     *  @throws  Exception
      */
     private  ModelAndView paging(HttpServletRequest request,
            HttpServletResponse response, ModelAndView mav)  throws  Exception  {
         //  获取当前页数，displaytag通过参数"page"传递这个值
                 int  pageNumber;
         if  (request.getParameter( " page " )  !=   null
                 &&   ! "" .equals(request.getParameter( " page " )))  {
            pageNumber  =  Integer.parseInt(request.getParameter( " page " ));
        }   else   {
            pageNumber  =   1 ;
        }
        PageList pageList  =   new  PageList();
        Map map  =  WebUtils.getParametersStartingWith(request,  " search_ " );
        Page page  =  dao.query(map, pageNumber, PAGE_SIZE);
                 //  设置当前页数
        pageList.setPageNumber(pageNumber);
                 //  设置当前页列表
        pageList.setList(page.getResults());
                 //  设置page size
        pageList.setObjectsPerPage(PAGE_SIZE);
                 //  设置总页数
        pageList.setFullListSize(page.getTotalCount());

        mav.addObject( " results " , pageList);

         return  mav;
    }

好了，现在直接在JSP上使用 displaytag就行了：
< display:table  name ="${results}"  id ="row"  class ="simple nocol"  pagesize ="${pageSize}"  export ="true"  
                    decorator ="org.displaytag.decorator.TotalTableDecorator"  
                    requestURI ="${pageContext.request.contextPath}/pageQuery.do?method=paging" >
                  < display:column  property ="date.time"  title ="日期"  format ="{0,date,yyyy-MM-dd}"  sortable ="false"   />
                 < display:column  property ="code"  title ="编码"  group ="1"  sortable ="false"   />
                 < display:column  property ="name"  title ="名称"  group ="1"  sortable ="false"   />
                  < display:column  property ="costTotal"  title ="总额(元)"  format ="{0,number,0,000}"  total ="true"  sortable ="false"   />

</ display:table >