Solve the problem that ${pagecontext.request.contextpath} is invalid

${pageContext.request.contextPath} yes JSP The way to get the absolute path
That is, take out the name of the deployed application or the name of the current project

For example, my project name is myself Enter... In the browser localhost:8080/myself

${pageContext.request.contextPath} What you take out is localhost:8080/myself, and http://localhost:8080 use / Instead of , So the path taken is /myself

${pageContext.request.contextPath } Invalidity is mostly due to web.xml The version is too low , It is widely used now web4.0 edition
Here is 4.0 Code for , Replace your web.xml that will do

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0" metadata-complete="true">
</web-app>