Java 在 JSP 中，是否可以打印名称在另一个变量中的变量的值？
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Is it possible, In JSP, to print the value of a variable whose name is in another variable?
提问by Rakesh Juyal
The problem i am having is like this there is variable
我遇到的问题是这样的有变量
<core:set var="type">*one of: load,migrate, or ...* </core:set>
and the value of load, migrate,is a map. Now, i want to print the value of these based on the type? Is it possible at all?
而load 和 migrate的值是一个映射。现在，我想根据类型打印这些值？有可能吗？
采纳答案by Nick Holt
This will achieve the same effect as @Chii's answer:
这将达到与@Chii 的回答相同的效果：
<c:set var="attributeName" value="foo"/>
<%
out.println(pageContext.getAttribute(attributeName) + " = " + pageContext.getAttribute(pageContext.getAttribute(attributeName)));
%>
This, nasty as it is, will list all the attributes in the page scopeif you need to do that:
这虽然很糟糕，但如果您需要这样做，它将列出页面范围内的所有属性：
<%
for (String attributeName : pageContext.getAttributeNamesInScope(PageContext.PAGE_SCOPE))
{
out.println(attributeName + " = " + pageContext.getAttribute(attributeName));
}
%>
Don't think there's a way to do this in JSTL, but you normally only need this during debugging so I don't have such a problem with the scriptlet code.
不要认为在 JSTL 中有一种方法可以做到这一点，但您通常只在调试期间需要它，所以我对 scriptlet 代码没有这样的问题。
回答by Chii
if they are not in a map, its hard.
如果他们不在地图上，那就很难了。
I assume you wanted to do it the way perl works: where you could type
我假设您想按照 perl 的工作方式进行操作：您可以输入的位置
$foo = "stuff";
$varName = "foo";
print $$varName; #prints "stuff"
That doesnt work in jsp.
这在jsp中不起作用。
If its a map,you can do ${mapValue[key]}. Info on this pagenear the Variables section
如果是地图，你可以做${mapValue[key]}。信息在此页附近变量部分
