Whitelabel 错误页面此应用程序没有配置错误视图，因此您将其视为后备答案

【问题标题】：Whitelabel Error Page This application has no configured error view, so you are seeing this as a fallbackWhitelabel 错误页面此应用程序没有配置错误视图，因此您将其视为后备
【发布时间】：2020-12-28 00:20:13
【问题描述】：

我开始构建一个 Spring Boot 应用程序，但我收到这种类型的错误“Whitelabel 错误页面 - 此应用程序没有配置的错误视图，因此您将其视为后备。” 我从https://start.spring.io/ 创建了项目。

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.3.3.RELEASE)

2020-09-09 16:12:00.389  INFO 19440 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication on ***** with PID 19440 (C:\Users\m.petraglia\Desktop\demo\target\classes started by m.petraglia in C:\Users\m.petraglia\Desktop\demo)
2020-09-09 16:12:00.391  INFO 19440 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
2020-09-09 16:12:01.024 DEBUG 19440 --- [           main] o.s.w.r.handler.SimpleUrlHandlerMapping  : Patterns [/webjars/**, /**] in 'resourceHandlerMapping'
2020-09-09 16:12:01.118 DEBUG 19440 --- [           main] o.s.w.r.r.m.a.ControllerMethodResolver   : ControllerAdvice beans: none
2020-09-09 16:12:01.138 DEBUG 19440 --- [           main] o.s.w.s.adapter.HttpWebHandlerAdapter    : enableLoggingRequestDetails='false': form data and headers will be masked to prevent unsafe logging of potentially sensitive data
2020-09-09 16:12:01.961  INFO 19440 --- [           main] o.s.b.web.embedded.netty.NettyWebServer  : Netty started on port(s): 8080
2020-09-09 16:12:01.967  INFO 19440 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 1.837 seconds (JVM running for 2.132)
2020-09-09 16:12:07.977 DEBUG 19440 --- [ctor-http-nio-2] o.s.w.s.adapter.HttpWebHandlerAdapter    : [22183960-1] HTTP GET "/hello"
2020-09-09 16:12:07.998 DEBUG 19440 --- [ctor-http-nio-2] o.s.w.r.handler.SimpleUrlHandlerMapping  : [22183960-1] Mapped to ResourceWebHandler ["classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"]
2020-09-09 16:12:08.000 DEBUG 19440 --- [ctor-http-nio-2] o.s.w.r.resource.ResourceWebHandler      : [22183960-1] Resource not found
2020-09-09 16:12:08.025 DEBUG 19440 --- [ctor-http-nio-2] org.springframework.web.HttpLogging      : [22183960-1] Resolved [ResponseStatusException: 404 NOT_FOUND] for HTTP GET /hello
2020-09-09 16:12:08.031 DEBUG 19440 --- [ctor-http-nio-2] org.springframework.web.HttpLogging      : [22183960-1] Writing "<html><body><h1>Whitelabel Error Page</h1><p>This application has no configured error view, so you  (truncated)...
2020-09-09 16:12:08.042 DEBUG 19440 --- [ctor-http-nio-2] o.s.w.s.adapter.HttpWebHandlerAdapter    : [22183960-1] Completed 404 NOT_FOUND

DemoApplication.java

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

    @GetMapping("/hello")
    public String hello(@RequestParam(value = "name", defaultValue = "World") String name) {
        return String.format("Hello %s!", name);
    }

}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example.demo</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

项目结构：

我不明白是什么问题。

【问题讨论】：

标签： java spring spring-boot

【解决方案1】：

尝试在类中添加@RestController注解

【讨论】：

【解决方案2】：

在我看来，也许你应该使用 html 文件在浏览器中运行它，如果你使用 thymeleaf，也应该包含依赖项

【讨论】：