想实现效果

掉后台接口跳转到thymeleaf网页，然而实际一直报错，如下图。

报错

org.thymeleaf.exceptions.TemplateInputException: Error resolving template [excelIndex], template might not exist or might not be accessible by any of the configured Template Resolvers
    at org.thymeleaf.engine.TemplateManager.resolveTemplate(TemplateManager.java:869) ~[thymeleaf-3.0.14.RELEASE.jar:3.0.14.RELEASE]
    at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:607) ~[thymeleaf-3.0.14.RELEASE.jar:3.0.14.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098) ~[thymeleaf-3.0.14.RELEASE.jar:3.0.14.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072) ~[thymeleaf-3.0.14.RELEASE.jar:3.0.14.RELEASE]
    at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:366) ~[thymeleaf-spring5-3.0.14.RELEASE.jar:3.0.14.RELEASE]
    at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:190) ~[thymeleaf-spring5-3.0.14.RELEASE.jar:3.0.14.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1401) ~[spring-webmvc-5.3.15.jar:5.3.15]
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1145) ~[spring-webmvc-5.3.15.jar:5.3.15]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1084) ~[spring-webmvc-5.3.15.jar:5.3.15]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.15.jar:5.3.15]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.15.jar:5.3.15]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.15.jar:5.3.15]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.56.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.15.jar:5.3.15]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.56.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.15.jar:5.3.15]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.15.jar:5.3.15]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.15.jar:5.3.15]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.15.jar:5.3.15]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.15.jar:5.3.15]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.15.jar:5.3.15]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1732) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
    at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

报错原因有x以下种

第1种场景错误：未设置返回格式

原因：前端的Ajax里我写了这么一段

dataType: "json",
contentType: 'application/json;charset=UTF-8',

要求返回Json形式的数据，但是后端的controller层我并没有设置返回格式，在controller层请求处理完了返回时，没有使用@RestController或@ResponseBody而返回了非json格式

解决方案：

请看下方链接 ↓
Error resolving template [excel/readExcel], template might not exist or might not be accessible by

第2种场景错误：html未打包进去（我的就是这种错误导致的）

原因： idea打包压根没把html文件打包进去，从而导致你访问就会失败，我的项目错误打包如下图

解决方案
每个人pom里面打包方式设置都不一样，我针对我的打包参数，添加一条扫描*/.html即可

<build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-resources-plugin</artifactId>
                <version>2.6</version>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>

        <!-- 如果不添加此节点mybatis的mapper.xml文件都会被漏掉。 -->
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                    <include>**/*.html</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

修改后再打包结果

注意：我的代码配置文件实际压根没有配置下面的东西，也就是说不配置也生效了
spring.thymeleaf.suffix=.html
spring.thymeleaf.prefix=classpath:/templates/

第3种场景错误：路径名写错了

原因1：名字写错了
代码return返回的路径名字写错了，比如页面叫index.html，结果你写成return "index1.html"

原因2：路径多加了个/
例如return "/index"，正式这个/导致报错的，解决：去掉返回前面的/即可，例如return "index" 。

原因3：templates文件夹下还有文件夹

这时代码return不应该写return "1_vuePractice"而应该写成return "vue/1_vuePractice"

(网上摘抄未验证过)第4种场景错误：在使用springboot的过程中，如果使用thymeleaf作为模板文件，则要求HTML格式必须为严格的html5格式，必须有结束标签，否则会报错。

解决办法如下：

在application.yml中添加以下配置

#thymeleaf
spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.suffix=.html
spring.thymeleaf.mode=LEGACYHTML5
spring.thymeleaf.encoding=UTF-8
spring.thymeleaf.content-type=text/html
spring.thymeleaf.cache=false

再在pom.xml 添加以下依赖

<dependency> 
<groupId>net.sourceforge.nekohtml</groupId> 
<artifactId>nekohtml</artifactId> 
<version>1.9.22</version> 
</dependency>

(网上摘抄未验证过)第5种场景错误：模板使用thymeleaf时pom引入不正确

检查：在External Libraries ->Maven:org.thymeleaf 查看版本

(网上摘抄未验证过)第6种场景错误：如果使用了视图解析器，检查视图跳转WebMvcConfigurer

项目都是这样配置的，所以没太在意这部分，多次检查才发现是路径有误：

改为：

第7种场景：检查资源文件夹属性

原因：新手创建了spring项目但是idea未识别并没来得及转换文件夹属性，导致spring启动压根识别不出来

错误文件夹格式长这样

解决方案：在resources右键 =》点击 Mark Directory as

最终成功了颜色长这样

第8种场景：文件不在templates文件夹内，而是自己创建了个文件夹

解决方案：只要配置扫描，能扫描到打包到jar包下就没问题，比如我自己的配置

<build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-resources-plugin</artifactId>
                <version>2.6</version>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>

        <!-- 如果不添加此节点mybatis的mapper.xml文件都会被漏掉。 -->
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                    <include>**/*.html</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

(网上摘抄未验证过)第9种场景错误：别人在POM引入 spring-boot-starter-actuator 健康管理依赖才成功

该场景是查看别人博客发现的，好像是其他方案都试了不好使，最后pom添加了健康监控依赖突然就好使了，具体我没看懂，详情请看下方的链接 ↓

Error resolving template [index], template might not exist or might not be accessible by any of the

template might not exist or might not be accessible by any of the configured Template Resolvers