我正在尝试使用Spring Boot和Thymeleaf设置一个基本项目，并将RequestMapping添加到基本的Thymeleaf模板中。但是，我在标题中遇到了错误消息，我不确定如何解决。
我首先使用 Spring Boot Initializer 创建了一个具有 web (spring-boot-starter-web) 和 ThymeLeaf(spring-boot-starter-thymeleaf) 依赖项的新项目。下载 Maven 项目并运行mvn spring-boot:run后，我能够成功启动我的服务器。
接下来，我尝试将 RequestMapping 添加到 ThymeLeaf 模板。我在src/main/java/com/example中使用以下代码创建了一个名为GreetingController的新控制器：
package com.example;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
@Controller
public class GreetingController {
@RequestMapping("/greeting")
public String greeting(@RequestParam(value="name", required=false, defaultValue="World") String name, Model model) {
model.addAttribute("name", name);
return "greeting";
}
}
此外，在src/main/resources/templates下，我添加了我的基本greeting.html模板：
<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<title>Getting Started: Serving Web Content</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<p th:text="'Hello, ' + ${name} + '!'" />
</body>
</html>
现在，当我重新运行服务器时，尝试转到localhost:8080/greeting时出现以下异常：
javax.servlet.ServletException: Circular view path [greeting]: would dispatch back to the current handler URL [/greeting] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)
at org.springframework.web.servlet.view.InternalResourceView.prepareForRendering(InternalResourceView.java:205) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:145) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1271) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:105) ~[spring-web-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:798) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1434) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.11.jar:8.5.11]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1153) [na:1.8.0]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [na:1.8.0]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.11.jar:8.5.11]
at java.lang.Thread.run(Thread.java:785) [na:1.8.0]
似乎问题在于百里香叶没有被正确识别或其他东西，尽管它被添加为pom中的依赖项。从我在网上其他线程中读到的内容来看，错误之所以发生，是因为 Spring 认为/greeting路径应该指向自身，因为方法末尾的语句return "greeting";。但是，我的理解是，这实际上应该是对greeting.html，百里香叶模板的引用。
我到底做错了什么？
就我而言，此问题是由于没有将百里叶的依赖项添加到项目中引起的。
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
我认为该问题与未正确下载的损坏依赖项有关。我删除了整个.m2文件夹并再次运行mvn spring-boot:run，一切正常。
这发生在我身上。我尝试了一切，重新下载依赖项等。最后，我关闭了IDE(想法)并重新打开了它。然后它奏效了。♂️
在此处查看导致循环依赖的问题的总体描述：https://www.baeldung.com/spring-circular-view-path-error
在您的情况下，我猜，在刚刚向 pom.xml 添加新的百里叶依赖项后，覆盖InternalResourceView的类尚不可用。这就是为什么mvn clean install或Intellij在这种情况下Project>Maven>Reload Project帮助的原因。