问题
Recently I upgraded my development tomcat from 7.0.0 to 7.0.4. I had things like:
<c:set var="static" value=".." />
<c:set var="class" value=".." />
Both worked on 7.0.0 but stopped working on 7.0.4. I opened a bug, it was closed, with the answer that:
In and of itself, that tag will compile.
The checks for Java identifiers were added to the EL processing so I suspect you have some illegal EL elsewhere on the page.
This didn't sound quite clear, but I didn't get a subsequent answer, so I looked at the EL spec. For the JSP 2.1 (the latest being 2.2) I found that:
Chapter 1, page 21: An identifier is constrained to be a Java identifier - e.g., no -, no /, etc.
And that's the most that I found. I would read this line in a way that the syntax requirements applying to java identifiers apply, but not the reserved words (since neighter class nor static appear in the list of reserved words in EL). The JLS isn't referred to for the term "Java identifier" (and it is for some other cases in the 2.2 spec, which I didn't review fully)
So, is Tomcat right to reject these names; which point of the spec they are referring to, and do you think they are interpreting it correctly.
回答1:
The spec says identifiers are limited to identifiers that would be valid in Java.
Both static and class are Java keywords, and so can't possibly be valid identifiers. You couldn't, for example, write this:
public int static = 7;
And so neither static nor class will be valid identifiers here either.
回答2:
From JSP 2.2 EL specification:
1.14 Reserved Words
The following words are reserved for the language and must not be used as identifiers.
and eq gt true instanceof or ne le false empty not lt ge null div modNote that many of these words are not in the language now, but they may be in the future, so developers must avoid using these words.
I don't see static, class, etc. This change in Tomcat 7.0.4 does not make sense to me.
来源：https://stackoverflow.com/questions/4019185/java-keywords-not-allowed-as-el-identifiers