应用displaytag完成大数据量分页显示的例子
应用displaytag在struts中完成大数据量分页显示，Oracle数据库
JSP文件：
<% ... @ taglib uri = " /WEB-INF/displaytag.tld " prefix = " disp " %>
< disp:table name ="resultList" export ="true" pagesize ="100" requestURI ="logQueryAction.do" sort ="external" id ="element" partialList ="true" size ="resultSize" >
< disp:column property ="operdate" title ="操作时间" ></ disp:column >
< disp:column property ="pername" title ="操作人员" ></ disp:column >
< disp:column property ="opertype" title ="操作类型" ></ disp:column >
</ disp:table >
name="resultList" 将记录集存在session或者request中的键值
export="true" 是否显示导出选项
pagesize="100" 每页显示100条数据
requestURI="logQueryAction.do" struts中action的名称，如果记录少，可以直接分页
sort="external" 外部排序
id="element" 表格id值，用于程序得相关的参数
partialList="true" 分段从数据库中读数据
size="resultSize" 记录的总条数，用于计算总页数
struts action:
String pageIndexName = new org.displaytag.util.ParamEncoder( " element " ).encodeParameterName(org.displaytag.tags.TableTagParameters.PARAMETER_PAGE); // 页数的参数名
int pageSize = 100 ; //每页显示的条数
int pageIndex = GenericValidator.isBlankOrNull(request.getParameter(pageIndexName)) ? 0 :(Integer.parseInt(request.getParameter(pageIndexName)) - 1 ); //当前页数
String sqlCount = " select count(*) from user_log a " ; //用于统计总记录数的sql语句
String sql = " select * from (select rownum as rid, t1.* from (select b.pername as pername,to_char(a.operdate,'yyyy-mm-dd hh24:mi:ss') as operdate, " +
" decode(a.opertype,'D','删除','M','修改','其他 ') as opertype, a.hphm as hphm from user_log a, " +
" (select asuser.userid as userid,nvl(asempmsg.pername,asuser.loginname) as pername from asuser,ASEMPMSG where asuser.perid=ASEMPMSG.perid(+)) b " +
" where a.userid=b.userid " ; // 查询语句
//构造查询条件
StringBuffer sb = new StringBuffer();
if (logQueryForm.getCzrqStart() != null && ! "" .equals(logQueryForm.getCzrqStart())) ... {
sb.append( " and a.operdate > to_date(' " + logQueryForm.getCzrqStart() + " ','yyyy-mm-dd') " );
}
if (logQueryForm.getCzrqEnd() != null && ! "" .equals(logQueryForm.getCzrqEnd())) ... {
sb.append( " and a.operdate <= to_date(' " + logQueryForm.getCzrqEnd() + " ','yyyy-mm-dd') " );
}
if (logQueryForm.getCzlx() != null && ! "" .equals(logQueryForm.getCzlx())) ... {
sb.append( " and a.opertype = ' " + logQueryForm.getCzlx() + " ' " );
}
if (logQueryForm.getCzry() != null && ! "" .equals(logQueryForm.getCzry())) ... {
sb.append( " and a.userid = ' " + logQueryForm.getCzry() + " ' " );
}
sqlCount += sb.toString();
sql += sb.toString() + " order by a.operdate desc) t1 where rownum<= "
+ (pageIndex + 1 ) * pageSize + " ) t2 where t2.rid> " + pageIndex * pageSize; //分页读取语句
// System.out.println(sb.toString());
DBBean db = new DBBean();
ResultSet rs = null ;
PreparedStatement prep = null ;
try ... {
List resultList = db.getResultList(sql); //将ResultSet保存在List里返回
request.setAttribute( " resultList " ,resultList); //把结果存入request
prep = db.getConnection().prepareStatement(sqlCount);
rs = prep.executeQuery();
if (rs.next()) ... {
request.setAttribute( " resultSize " , new Integer(rs.getInt( 1 ))); //将总记录数保存成Intger实例保存在request中
}
}
catch (Exception ex) ... {
ex.printStackTrace();
}
finally ... {
if (db != null ) ... {
db.closeConnection(); //关闭连接
}
}
其中的页面导航是英文的，只要修改org.displaytag.properties.TableTag.properties配置文件就可以把英文改成中文。同时还可以指定导出文件的类型以及文件名。
export.excel = true
export.excel.label = <span class = " export excel " >Excel </span>
export.excel.include_header = true
export.excel.filename = export.xls
如果不指定文件名，在点击导出excel的时候，就会在ie窗口中打开excel文件。很烦人！
指定文件名后就可以选择保存和打开了。
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