layui中用${ctx}作为引用地址
```html
<link rel="icon" href="${ctx}/../static/images/favicon.ico">
<link rel="stylesheet" href="${ctx}/../static/lib/layui-v2.5.5/css/layui.css" media="all">
<link rel="stylesheet" href="${ctx}/../static/css/layuimini.css" media="all">
<link rel="stylesheet" href="${ctx}/../static/lib/font-awesome-4.7.0/css/font-awesome.min.css" media="all">
<link rel="stylesheet" href="${ctx}/../static/css/formSelects-v4.css" media="all">
<link rel="stylesheet" href="${ctx}/../static/css/public.css" media="all">
<script src="${ctx}/../static/lib/layui-v2.5.5/layui.js" charset="utf-8"></script>
<script src="${ctx}/../static/js/lay-config.js" charset="utf-8"></script>
<script type="text/javascript">
var ctx = "${ctx}";
</script>
一直报
```bash
freemarker.core.InvalidReferenceException: The following has evaluated to null or missing:
==> ctx [in template "common.ftl" at line 1, column 26]
----
Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----
----
FTL stack trace ("~" means nesting-related):
- Failed at: ${ctx} [in template "common.ftl" at line 1, column 24]
- Reached through: #include "common.ftl" [in template "index.ftl" at line 5, column 5]
----
at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.EvalUtil.coerceModelToTextualCommon(EvalUtil.java:481) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:401) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:370) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.DollarVariable.calculateInterpolatedStringOrMarkup(DollarVariable.java:100) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.DollarVariable.accept(DollarVariable.java:63) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.visit(Environment.java:347) [freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.visit(Environment.java:353) [freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.include(Environment.java:2955) [freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Include.accept(Include.java:171) [freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.visit(Environment.java:347) [freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.visit(Environment.java:353) [freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.process(Environment.java:326) [freemarker-2.3.31.jar:2.3.31]
at freemarker.template.Template.process(Template.java:383) [freemarker-2.3.31.jar:2.3.31]
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:391) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:304) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:255) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:179) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:316) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1396) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1141) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1080) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) [spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) [spring-webmvc-5.3.8.jar:5.3.8]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) [tomcat-embed-core-9.0.48.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) [spring-webmvc-5.3.8.jar:5.3.8]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) [tomcat-embed-core-9.0.48.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:228) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) [spring-web-5.3.8.jar:5.3.8]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) [spring-web-5.3.8.jar:5.3.8]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) [spring-web-5.3.8.jar:5.3.8]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.8.jar:5.3.8]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1723) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.48.jar:9.0.48]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_292]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_292]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.48.jar:9.0.48]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_292]
2021-08-05 15:25:29.317 ERROR 46384 --- [p-nio-80-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is freemarker.core.InvalidReferenceException: The following has evaluated to null or missing:
==> ctx [in template "common.ftl" at line 1, column 26]
----
Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----
----
FTL stack trace ("~" means nesting-related):
- Failed at: ${ctx} [in template "common.ftl" at line 1, column 24]
- Reached through: #include "common.ftl" [in template "index.ftl" at line 5, column 5]
----] with root cause
freemarker.core.InvalidReferenceException: The following has evaluated to null or missing:
==> ctx [in template "common.ftl" at line 1, column 26]
----
Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----
----
FTL stack trace ("~" means nesting-related):
- Failed at: ${ctx} [in template "common.ftl" at line 1, column 24]
- Reached through: #include "common.ftl" [in template "index.ftl" at line 5, column 5]
----
at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.EvalUtil.coerceModelToTextualCommon(EvalUtil.java:481) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:401) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:370) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.DollarVariable.calculateInterpolatedStringOrMarkup(DollarVariable.java:100) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.DollarVariable.accept(DollarVariable.java:63) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.visit(Environment.java:347) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.visit(Environment.java:353) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.include(Environment.java:2955) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Include.accept(Include.java:171) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.visit(Environment.java:347) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.visit(Environment.java:353) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.core.Environment.process(Environment.java:326) ~[freemarker-2.3.31.jar:2.3.31]
at freemarker.template.Template.process(Template.java:383) ~[freemarker-2.3.31.jar:2.3.31]
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:391) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:304) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:255) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:179) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:316) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1396) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1141) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1080) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.8.jar:5.3.8]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.8.jar:5.3.8]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.48.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.8.jar:5.3.8]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.48.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:228) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.8.jar:5.3.8]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.8.jar:5.3.8]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.8.jar:5.3.8]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.8.jar:5.3.8]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.8.jar:5.3.8]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.8.jar:5.3.8]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1723) [tomcat-embed-core-9.0.48.jar:9.0.48]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.48.jar:9.0.48]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_292]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_292]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.48.jar:9.0.48]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_292]
2021-08-05 15:25:29.393 ERROR 46384 --- [p-nio-80-exec-1] s.e.ErrorMvcAutoConfiguration$StaticView : Cannot render error page for request [/] and exception [The following has evaluated to null or missing:
==> ctx [in template "common.ftl" at line 1, column 26]
----
Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----
----
FTL stack trace ("~" means nesting-related):
- Failed at: ${ctx} [in template "common.ftl" at line 1, column 24]
- Reached through: #include "common.ftl" [in template "index.ftl" at line 5, column 5]
----] as the response has already been committed. As a result, the response may have the wrong status code.
加入
后问题解决，但是地址栏出现request地址，导致资源访问异常
请教各位巨巨如何破解……
