http://www.iteye.com/problems/34149/
The error reported by <jsp:include page=" /project name/templates/header.jsp "></jsp:include> is org.apache.jasper.JasperException: javax.servlet.ServletException: File " /project name/templates /header.jsp " not found The page that cannot be found is the page given by the parameter "/project name/templates/header.jsp" This path after removing the leading "/" should be absolutely fine, unless this "/ "Does not represent the root directory (server address) of the server <jsp:include page=" http://localhost:8080/project name/templates/header.jsp "> The error reported is org.apache.jasper.JasperException: javax .servlet.ServletException: File " /templates/http:/localhost:8080/project name/templates/header.jsp " not found The page that cannot be found is more than the parameter /templates/
That is to say, there is no "special treatment" because the parameter starts with "http://", but it is treated as a normal string, and it is treated as a relative path because it does not start with "/". And added "/templates/" in front of
it. If so, this "/templates/" should be its own location. According to this reasoning, this "/" represents? ? ?
Experimented again
<jsp:include page=" ../templates/ a non-existent page "></jsp:include>
reported an error as
org.apache.jasper.JasperException: javax.servlet.ServletException: File " /templates /A non-existent page " not found
Conclusion I observed it, thought about it, and got it. It turned out that I made a big circle. The problem is actually very simple: To summarize, the application of the <jsp:include> tag in JSP: 1. Dynamic syntax such as <%= %> is not supported, especially the value of the page attribute can only be a hard-coded string (I just heard that there are some special syntaxes of its own, which I will learn later) 2, For the path problem of the imported page, two application methods of "absolute path" and "relative path" can also be used. An absolute path is a path starting with "/", and other paths, including those starting with "http://", are relative paths, and "./", "../", etc. can be used.
相对路径 没什么好说的。强调一点，这里的相对路径也是相对于访问页面的URL的路径，本质上与页面文件在项目中的存储位置没直接关系，所以这里用相对路径时也存在由于访问URL不确定带来的问题（是不是这样呢？如文章开头说的，这里都是我自己的结论）。
主要是绝对路径的问题：
我们知道大部分情况下写在页面（不管静态还是动态）里并输出到IE中的路径都是由IE来解析的，以“/”开头的绝对路径 这个“/”代表的是服务器的根目录：比如访问URL为 http://localhost:8080/项目名/templates/template.jsp
那么“/”代表的就是 "http://localhost:8080/" 而并不带有项目名信息。
而<jsp:include>引入页面的过程，是在服务器运行向IE输出数据的过程中由JAVA程序调用执行，路径也当然由JAVA程序来解析，此时以"/"开头的绝对路径中的“/” 代表的已经是本项目的根目录了。
比如 URL为 http://localhost:8080/项目名/templates/template.jsp
那么“/”代表的就是 "http://localhost:8080/项目名/"。已经带有了项目名信息。
同时，也不用像引入JS CSS文件那样在路径前加上 <%=request.getContextPath()%> 来解决项目名本身修改的问题了。只需一个“/”就什么也不用管了。
如上所述：
需求需要的这段代码其实很简单
需要被任意位置的页面引入的页面 存放在项目根目录下的templates目录下