Why do I always get Whitelabel Error Page with status “404” while running a simple Spring Boot Application

问题

My Controller

@Controller
//@RequestMapping("/")
//@ComponentScan("com.spring")
//@EnableAutoConfiguration
public class HomeController {

    @Value("${framework.welcomeMessage}")
    private String message;

    @RequestMapping("/hello")
    String home(ModelMap model) {
        System.out.println("hittin the controller...");
        model.addAttribute("welcomeMessage", "vsdfgfgd");
        return "Hello World!";
    }

    @RequestMapping(value = "/indexPage", method = RequestMethod.GET)
    String index(ModelMap model) {
        System.out.println("hittin the index controller...");
        model.addAttribute("welcomeMessage", message);
        return "welcome";
    }

    @RequestMapping(value = "/indexPageWithModel", method = RequestMethod.GET)
    ModelAndView indexModel(ModelMap model) {
        System.out.println("hittin the indexPageWithModel controller...");
        model.addAttribute("welcomeMessage", message);
        return new ModelAndView("welcome", model);
    }
}

My JSP (welcome.jsp) inside /WEB-INF/jsp (parent folder is WebContent)

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Welcome to Spring Boot</title>
</head>

<body>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
Message: ${message}
</body>
</html>

My pom.xml

<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>SpringBootPlay</groupId>
    <artifactId>SpringBootPlay</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.0.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.1.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-io</artifactId>
            <version>1.3.2</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>com.jcabi</groupId>
            <artifactId>jcabi-log</artifactId>
            <version>0.17</version>
        </dependency>
    </dependencies>
    <properties>
        <java.version>1.8</java.version>
        <start-class>com.spring.play.BootLoader</start-class>
        <main.basedir>${basedir}/../..</main.basedir>
        <m2eclipse.wtp.contextRoot>/</m2eclipse.wtp.contextRoot>
    </properties>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <useSystemClassLoader>false</useSystemClassLoader>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

My App Initializer

@EnableAutoConfiguration
@SpringBootApplication
@ComponentScan({ "com.spring.controller" })
@PropertySources(value = { @PropertySource("classpath:/application.properties") })
public class BootLoader extends SpringBootServletInitializer {

    final static Logger logger = Logger.getLogger(BootLoader.class);

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(BootLoader.class);
    }

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

I even added thymeleaf dependency to my pom. It still didn't work. When ever I hit localhost:8080/hello or /indexPage or /indexPageWithModel it always says

Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Wed Sep 21 21:34:18 EDT 2016 There was an unexpected error (type=Not Found, status=404). ]/WEB-INF/jsp/welcome.jsp

My application.properties

spring.mvc.view.prefix: /WEB-INF/jsp/
spring.mvc.view.suffix: .jsp
framework.welcomeMessage=Welcome to Dashboard

Please help me. Thanks!

回答1:

Figured it out myself.

When I converted my dynamic webproject into maven project it did not create the folder structure this way

src/main/java

and

src/main/resources

and

src/main/webapp

I manually created myself and moved the jsp files from WebContent/WEB-INF/jsp to src/main/webapp/WEB-INF/jsp and modified the Java build path in the project properties.

Then I restarted the embedded tomcat and tried it again. It worked.

回答2:

This is one of most common error that almost all the spring boot beginners face.

Solution to this is very simple, - your Bootstrap class should know the package or the class path where it should refer in order access the component/controller. Hence you need to specify like :- @ComponentScan(basePackages= {"org.test.controller"})

P.S.- here "org.test.controller" is a qualified name of the package where I have kept my controller.

回答3:

Cause of this type of errors is due to Bootstrap class is not aware of the location of the controller where it needs to be looked.

In such cases, we need to specify the package or classpath which we can refer to using @ComponentScan(basePackages={"com.sample.controller"}) where In my case I have specified package as com.sample.controller.

来源：https://stackoverflow.com/questions/39628930/why-do-i-always-get-whitelabel-error-page-with-status-404-while-running-a-simp

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jsp

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