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我有一個jsp頁面，該頁面超鏈接到另一個jsp頁面。如果我們從下面所示的圖像點擊「更新首選項」，然後打開第二圖象：如何在jsp中顯示先前選定的值
下面是第二圖像中顯示的JSP代碼：
<body>
<center>
<div style="font-style:bold;font-size:30;color:black"> Data Platform - Monitor </div>
</center>
<BR><BR>
<%!
VoltDAOImpl voltDao = new VoltDAOImpl();
%>
<form action="dp_monitor.jsp" method="get" >
<table width="350" border="0">
<tr valign="Left">
<td><b>Client Acronym: </b> </td><td> <b> <input type="text" name="client_acronym" value="PEAKM"></b></td>
</tr>
<tr valign="Left">
<td><b>Sort By :</b></td>
<td>
<select name="sort_by">
<option selected="true" value="notional">notional</option>
<option value="arr_mid_slp">arr mid slippage</option>
<option value="order_qty">order qty</option>
<option value="liq_consmption">liq consmption</option>
<option value="arr_last_slp">arr last slippage</option>
<option value="ivwap_slp">ivwap slppage</option>
<option value="exec_qty">exec qty</option>
<option value="leaves_qty">leaves qty</option>
<option value="limit_px">limit px</option>
<option value="avg_px">avg px</option>
<option value="last_px">last px</option>
<option value="last_qty">last qty</option>
<option value="transact_time">transact time</option>
<option value="arr_mid_px">arr mid px</option>
<option value="ivwap_volume">ivwap volume</option>
<option value="ivap_px">ivap px</option>
<option value="arr_last_px">arr last px</option>
<option value="end_last_px">end last px</option>
</select>
</td>
</tr>
<tr valign="Left">
<td><b>Algo: </b> </td>
<td>
<select name="algo">
<option selected="true" value="">ALL</option>
<%
try{
List<String> algo_list= voltDao.getDistinctAlgos("PEAKM",voltDao.client);
for(String algo : algo_list)
{
out.println("<option value=\""+algo+"\">"+algo+"</option>");
}
} catch(Exception e){System.out.println(" error in getting algos" ); }
%>
</select>
</tr>
<tr valign="Left">
<td><b>ListId: </b> </td>
<td><select name="listid">
<option selected="true" value="">ALL</option>
<%
try {
List<String> list_id__list= voltDao.getDistinctListID("PEAKM",voltDao.client);
for(String list_id : list_id__list)
{
out.println("<option value=\""+list_id+"\">"+list_id+"</option>");
}
} catch(Exception e){System.out.println(" error in getting listids" ); }
%>
</select>
</td>
</tr>
<tr valign="Left">
<td><b>Refresh : </b> </td>
<td>
<select name="refresh">
<option value="1">1 sec</option>
<option value="3">3 secs</option>
<option value="5">5 secs</option>
<option value="10">10 secs</option>
<option value="15">15 secs</option>
<option value="30">30 secs</option>
<option value="45">45 secs</option>
<option value="60">1 min</option>
<option value="120">2 min</option>
<option value="180">3 min</option>
<option value="240">4 min</option>
<option value="300" selected>5 min</option>
</select>
</td> </tr>
<tr><td></td> </tr>
<tr><td></td> </tr>
<tr><td></td> </tr>
<tr> <td><button type="submit">Update</button></td>
<td><button type="reset">Clear</button></td>
</tr>
</table>
</form>
</body>
因此，每次我選擇一個首選項，比如"Refresh「從下拉菜單中選擇5 secs，然後點擊Update，所以它會返回到第一個jsp（第一個圖像sh自己在上面）。現在當我再次點擊「Update Preferences」時，它會顯示默認選擇值5 mins而不是5 secs。如何獲得以前選擇的偏好，以便每次點擊Update Preferences時顯示？
更新： 我將此添加到我的第二個JSP：
<%
String refreshValue = request.getParameter("refresh");
if(refreshValue==null){
refreshValue = "60";
}
%>
<td><b>Refresh : </b> </td>
<td>
<select name="refresh">
<option value="1" <% if(refreshValue.equals("1")) { %> selected <% } %>>1 sec</option>
<option value="3" <% if(refreshValue.equals("3")) { %> selected <% } %>>3 secs</option>
<option value="5" <% if(refreshValue.equals("5")) { %> selected <% } %>>5 secs</option>
<option value="10" <% if(refreshValue.equals("10")) { %> selected <% } %>>10 secs</option>
<option value="15" <% if(refreshValue.equals("15")) { %> selected <% } %>>15 secs</option>
<option value="30" <% if(refreshValue.equals("30")) { %> selected <% } %>>30 secs</option>
<option value="45" <% if(refreshValue.equals("45")) { %> selected <% } %>>45 secs</option>
<option value="60" <% if(refreshValue.equals("60")) { %> selected <% } %>>1 min</option>
<option value="120" <% if(refreshValue.equals("120")) { %> selected <% } %>>2 min</option>
<option value="180" <% if(refreshValue.equals("180")) { %> selected <% } %>>3 min</option>
<option value="240" <% if(refreshValue.equals("240")) { %> selected <% } %>>4 min</option>
<option value="300" <% if(refreshValue.equals("300")) { %> selected <% } %>>5 min</option>
</select>
這給我的第一個JSP（dp_monitor）：
<input type="hidden" name="refresh" value="<%=request.getParameter("refresh")%>">
<%String refresh = request.getParameter("refresh");
if(("".equals(refresh)||refresh==null) )
refresh="4000";
// Set refresh, autoload time
response.setIntHeader("Refresh", Integer.parseInt(refresh));
// Get current time
Calendar calendar = new GregorianCalendar();
String am_pm;
int hour = calendar.get(Calendar.HOUR);
int minute = calendar.get(Calendar.MINUTE);
int second = calendar.get(Calendar.SECOND);
if(calendar.get(Calendar.AM_PM) == 0)
am_pm = "AM";
else
am_pm = "PM";
if(hour == 0)
hour = 12;
String CT = hour+":"+ minute +":"+ second +" "+ am_pm;
out.println("Last Refresh Time: " + CT + "\n");%>
但是，它時，我選擇「更新某個值偏好設置「，然後點擊」更新「，然後再回來，它只需要refreshValue作爲null，因此只顯示1 min被選中。該怎麼辦？
，你在哪裏存儲此偏好？因爲現在，選擇'<選項值=「300」選項> 5分鐘'選擇'5分鐘'。您需要獲取保存的值（文件，數據庫，緩存）並使用一些JSTL將'selected'添加到相應的 – AxelH