[英]How to show drop down result based on selected radio button | JSP
我正在嘗試編寫一個JSP頁面,該頁面需要根據同一頁面上的選擇國家/地區單選按鈕顯示狀態的下拉列表。 當我運行該頁面時,即使選擇了USA單選按鈕,它也會顯示c:otherdown下拉列表。 請幫忙
USA:<html:radio property="country" value="country" >
<c:set var ="p" value="usa"/>
</html:radio>
Germany:<html:radio property="country" value="country" >
<c:set var ="p" value="germany"/>
</html:radio>
<br>
list:
<c:choose>
<c:when test = "${p == processors }" >
//drop down for states in USA
</c:when>
<c:otherwise >
//drop down for states in germany
</c:otherwise>
</c:choose>
enter code here
您必須以某種方式將用戶的選擇傳播到服務器端,因為使用JSP,您主要可以采用這種方式。 一個工作示例:
<%@ taglib uri = "http://java.sun.com/jsp/jstl/core" prefix = "c" %>
<HTML>
<HEAD>
<TITLE>Reading Radio Buttons</TITLE>
</HEAD>
<BODY>
<H1>Reading Radio Buttons</H1>
<%
boolean radio2checked = false;
if(request.getParameter("radios") != null) {
if(request.getParameter("radios").equals("radio1")) {
out.println("Radio button 1 was selected.<BR>");
}
else {
out.println("Radio button 1 was not selected.<BR>");
}
if(request.getParameter("radios").equals("radio2")) {
out.println("Radio button 2 was selected.<BR>");
radio2checked = true;
}
else {
out.println("Radio button 2 was not selected.<BR>");
}
}
pageContext.setAttribute("showUSAdropdown", radio2checked);
String checked = radio2checked ? "checked=\"checked\"" : "";
%>
<FORM name="radioform" METHOD="post">
<INPUT TYPE="radio" onclick="document.radioform.submit()" NAME="radios" VALUE="radio1" CHECKED>
Radio Button 1
<BR>
<INPUT TYPE="radio" <%=checked%> onclick="document.radioform.submit()" NAME="radios" VALUE="radio2">
Radio Button 2
<BR>
States:
<SELECT name="states">
<c:choose>
<c:when test="${showUSAdropdown}">
<option>Alabama</option>
<option>Washington</option>
</c:when>
<c:otherwise>
<option>Germany</option>
</c:otherwise>
</c:choose>
</SELECT>
</FORM>
</BODY>
</HTML>
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