JSP中存在检查属性 [英] Checking attribute exists in JSP

问题描述

我有一些扩展了超类的类，在JSP中，我想显示这些类的一些属性.我只想制作一个JSP，但我不事先知道对象是否具有属性.因此，我需要一个JSTL表达式或一个标记来检查我传递的对象是否具有此属性(类似于javascript中的in运算符，但在服务器中).

I have some classes which extends a superclass, and in the JSP I want to show some attributes of these classes. I only want to make one JSP, but I don't know in advance if the object has an attribute or not. So I need a JSTL expression or a tag which checks that the object I pass has this attribute (similar to in operator in javascript, but in the server).

<c:if test="${an expression which checks if myAttribute exists in myObject}">
    <!-- Display this only when myObject has the atttribute "myAttribute" -->
    <!-- Now I can access safely to "myAttribute" -->
    ${myObject.myAttribute}
</C:if>

我怎么能得到这个?

谢谢.

推荐答案

使用JSTL

Make use of JSTL c:catch.

<c:catch var="exception">${myObject.myAttribute}</c:catch>
<c:if test="${not empty exception}">Attribute not available.</c:if>

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