ext grid 数据库分页实现

看了robbin 关于hibernate 分页的老帖(http://www.iteye.com/topic/261)，把ext grid 的数据库分页整了下，完全满足需要，呵呵，贴出代码与大家共同学习下：
  DAO代码：

/**  
       * 获取符合查询条件的记录总数  
       * @param detachedCriteria  hibernate Criteria 查询对象，由service组装  
       * @return  
       */  
  public Long getRecordCount(final DetachedCriteria detachedCriteria) {   
        return (Long) getHibernateTemplate().execute(new HibernateCallback() {   
            public Object doInHibernate(Session session)   
                    throws HibernateException {   
                Criteria criteria = detachedCriteria   
                        .getExecutableCriteria(session);   
                long count = Long.parseLong((criteria.setProjection(Projections   
                        .rowCount()).uniqueResult()).toString());   
                criteria.setProjection(null);   
                return Long.valueOf("" + count);   
            }   
        }, true);   
    }   
/**  
       * 获取符合条件的查询记录  
       * @param detachedCriteria  
       * @param startResult  
       * @param limitResult  
       * @return  
       */  
  
    public List listByConditions(final DetachedCriteria detachedCriteria,   
            final int startResult, final int limitResult) {   
  
        return (List) getHibernateTemplate().execute(new HibernateCallback() {   
            public Object doInHibernate(Session session)   
                    throws HibernateException {   
                Criteria criteria = detachedCriteria   
                        .getExecutableCriteria(session);   
                criteria.setFirstResult(startResult);   
                criteria.setMaxResults(limitResult);   
                return criteria.list();   
            }   
        }, true);   
    }  

服务层：

/**  
     * 获取所有日志列表  
     * @param startResult   查询记录起点  
     * @param limitResult   简要列表每页最大记录数  
     * @param sortRecord    简要列表排序字段名  
     * @param dirRecord     简要列表排序类型 DESE/ASC  
     * @return  
     */  
public JSONArray getAllLogs(String startResult,String limitResult,   
              String sortRecord,String dirRecord) {   
           
        try {   
            DetachedCriteria detachedCriteria = DetachedCriteria.forClass(TDeasLog.class);     
            if(dirRecord.equals("ASC"))   
                detachedCriteria.addOrder(Order.asc(sortRecord));   
            else  
                detachedCriteria.addOrder(Order.desc(sortRecord));   
                 
            Long count = logDAO.getRecordCount(detachedCriteria);//获取符合条件的记录总数       
                 
            List list = logDAO.listByConditions(detachedCriteria, Integer.parseInt(startResult),    
                      Integer.parseInt(limitResult));//获取符合条件记录   
            if(list.size()>0){   
                List jsonlist = new ArrayList();   
                Iterator it = list.iterator();   
                while (it.hasNext()){   
                    Log log = (Log )it.next();   
                    Map map = new HashMap();   
                    map.put("taskId", log .getTaskId());   
                    map.put("rwfssj", log .getRwfssj());   
                    map.put("rwjssj", log .getRwjssj());   
                            ....                                                       
                    jsonlist.add(map);                 
                }   
                Map m = new  HashMap();   
                m.put("results", count.toString());   
                m.put("rows", jsonlist);   
                   
                JSONArray jsonArray = JSONArray.fromObject(m);   
                return jsonArray;     
            }else  
                return null;   
        } catch (Exception e) {   
            e.printStackTrace();   
            return null;   
        }   

action 代码：

public ActionForward getAllLogs(ActionMapping mapping, ActionForm form,   
            HttpServletRequest request, HttpServletResponse response) {   
           
        String startResult = request.getParameter("start");   
        String limitResult = request.getParameter("limit");   
        String sortRecord = request.getParameter("sort");   
        String dirRecord = request.getParameter("dir");   
           
        JSONArray jsonArray = this.getLogService().getAllLogs(startResult,limitResult,sortRecord,dirRecord);           
           
        if(jsonArray != null){   
            String jsonstr = jsonArray.toString();   
            //去除JSON对象前的[]     
            String json = jsonstr.substring(1, jsonstr.length()-1);            
            response.setContentType("text/json; charset=utf-8");    
            try {   
                response.getWriter().print(json);   
            } catch (IOException e) {   
                log.error("获取日志实例列表失败，异常："+e.getMessage());   
            }   
        }else{//返回空数据，格式：{"rows":[],"results":"0"}   
            List list = new ArrayList();   
            Map map1 = new HashMap();   
            list.add(map1);   
            Map m = new  HashMap();   
            m.put("results", "0");   
            m.put("rows", list);   
            JSONArray json = JSONArray.fromObject(m);          
            String jsonString = json.toString();   
            String jsonstr =jsonString.substring(1, jsonString.length()-1);   
            response.setContentType("text/json; charset=utf-8");    
            try {   
                response.getWriter().print(jsonstr);   
            } catch (IOException e) {   
                log.error("获取日志实例列表失败，异常："+e.getMessage());   
            }   
        }          
        return null;   
    }  

开始无数据时怎么也不能显示PagingToolbar 的emptyMsg，后来发现空数据时组织格式错误，忘记去掉 [{"rows":[],"results":"0"}]这部分的“[]”，这个小问题折磨了俺好久，呵呵，要细心啊～！

 var datastore = new Ext.data.Store({   
       proxy: new Ext.data.HttpProxy({   
           url: 'logManage.do?method=getAllLogs'  
       }),   
       reader: new Ext.data.JsonReader({   
        root               : 'rows',   
           totalProperty      : 'results',   
           id: 'taskID'  
       }, [   
           {name: 'taskId'},   
           {name: 'rwfssj'},   
           {name: 'rwjssj'},   
           ....   
       ]),   
        remoteSort: true  
   });   
   datastore.setDefaultSort('taskId','ASC');   
   datastore.load({params:{start:0, limit:10}});   
       
var sm = new Ext.grid.CheckboxSelectionModel();   
var colModel = new Ext.grid.ColumnModel([   
    new Ext.grid.RowNumberer(),   
    { header:'任务ID', width:100, sortable:true, locked:true, dataIndex:'taskId'},   
    { header:'任务类型', width:100, sortable:true, locked:false, dataIndex:'rwlb'},   
    { header:'任务状态', width:100, sortable:true, locked:false, dataIndex:'rwzt'},   
    ......   
]);   
       
var LogGrid = new Ext.grid.GridPanel({   
    ds                  : datastore,   
    cm                  : colModel,   
    sm                  : sm,   
    id                  : 'LogGrid',   
    title               : '日志列表',   
    autoHeight          : true,   
       width               : '100%',   
       loadMask            : true,   
     buttons            : [{   
            text        : '查询',   
            tooltip     : '日志查询',   
            handler     : logSearch   
     },{   
            text        : '关闭',   
            tooltip     : '关闭窗口',   
            handler     : closeForm   
     }],   
       buttonAlign         : 'right',   
       bbar                : new Ext.PagingToolbar({   
           id              : 'pagingbar',   
           pageSize        : 10,   
           store           : datastore,   
           displayInfo     : true  
            })         
});