在JSP中包含/导入文件之前,如何检查文件是否存在? [英] How can you check if a file exists before including/importing it in JSP?
问题描述
假设 requestScope.importMe 期待JSP文件的路径
Assuming that requestScope.importMe is expecting a path to a JSP file
<c:choose>
<c:when test="${!empty requestScope.importMe && fileExists(requestScope.importMe) }">
<c:import url="${requestScope.importMe}" />
...
</c:choose>
如何在尝试包含文件之前检查文件是否存在,以免引发错误?
How can I check if the file exists before trying to include it so that an error is not thrown?
我更喜欢使用JSTL标签的解决方案。
I'd prefer a solution using JSTL tags.
推荐答案
Put it in a c:catch
tag. It will catch any thrown Exception
for you.
<c:catch var="e">
<c:import url="${url}" />
</c:catch>
<c:if test="${!empty e}">
Error: ${e.message}
</c:if>
但我必须承认我不喜欢 c:catch
方法。这是滥用控制流量的例外情况。如果可以的话,而是在servlet或 JavaBean 中执行此工作,而不是在 File#exists()
(和 ServletContext#getRealPath()
)。
I must however admit that I don't like the c:catch
approach. It's abusing exceptions to control the flow. If you can, rather do this job in a servlet or JavaBean instead with help of File#exists()
(and ServletContext#getRealPath()
).
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