Whitelabel Error Page the controller cannot be scanned - Spring boot- jsp

Question

I am learning how to build web application by spring boot.
When I try to use controller to use @Controller to show the jsp page, the "Whitelabel Error Page This application has no explicit mapping for /error, so you are seeing this as a fallback." is shown.

I've considered if the problem is about component scan, but when I change the @Controller to @RestController, the web page could show the string I typed.

I would like to ask why the bean cannot be scanned when the @Controller is used and how can I fixed the problem.

This is the controller class

package com.lms.controllers;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.GetMapping;


@Controller
public class MainController {
    
    @GetMapping("h")
    public String init(ModelMap Model) {
        return "index";
    }
}

the application properties

spring.mvc.view.prefix = /WEB-INF/views/
spring.mvc.view.suffix = .jsp
spring.datasource.url = jdbc:mysql://localhost:3306/mydb?useSSL=false

spring.datasource.username = root
spring.datasource.password = 0000

#Allows Hibernate to generate SQL optimized for a particular DBMS
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

spring.jpa.hibernate.ddl-auto = update

logging.level.org.hibernate.SQL = debug

the pom.xml file

<?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>2.5.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.library</groupId>
    <artifactId>library</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>LMS</name>
    <description>Demo project for Spring Boot Library Management System</description>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    
    
    
    <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>
        
        <!-- Persistance related -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        
        
        
        <dependency>
          <groupId> org.apache.tomcat.embed </groupId>
          <artifactId> tomcat-embed-jasper </artifactId>
          <scope> provided </scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>
    </dependencies>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

the log

2021-08-22 02:55:47.719 DEBUG 17084 --- [nio-8080-exec-1] o.s.w.s.v.ContentNegotiatingViewResolver : Selected 'text/html' given [text/html, application/xhtml+xml, image/webp, image/apng, application/xml;q=0.9, application/signed-exchange;v=b3;q=0.9, */*;q=0.8]
2021-08-22 02:55:47.719 DEBUG 17084 --- [nio-8080-exec-1] o.s.web.servlet.view.JstlView            : View name 'index', model {}
2021-08-22 02:55:47.721 DEBUG 17084 --- [nio-8080-exec-1] o.s.web.servlet.view.JstlView            : Forwarding to [/WEB-INF/views/index.jsp]
2021-08-22 02:55:47.726 DEBUG 17084 --- [nio-8080-exec-1] o.j.s.OpenEntityManagerInViewInterceptor : Closing JPA EntityManager in OpenEntityManagerInViewInterceptor
2021-08-22 02:55:47.726 DEBUG 17084 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed 404 NOT_FOUND
2021-08-22 02:55:47.727 DEBUG 17084 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : "ERROR" dispatch for GET "/error", parameters={}
2021-08-22 02:55:47.728 DEBUG 17084 --- [nio-8080-exec-1] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped to org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController#errorHtml(HttpServletRequest, HttpServletResponse)
2021-08-22 02:55:47.728 DEBUG 17084 --- [nio-8080-exec-1] o.j.s.OpenEntityManagerInViewInterceptor : Opening JPA EntityManager in OpenEntityManagerInViewInterceptor
2021-08-22 02:55:47.741 DEBUG 17084 --- [nio-8080-exec-1] o.s.w.s.v.ContentNegotiatingViewResolver : Selected 'text/html' given [text/html, text/html;q=0.8]
2021-08-22 02:55:47.744 DEBUG 17084 --- [nio-8080-exec-1] o.j.s.OpenEntityManagerInViewInterceptor : Closing JPA EntityManager in OpenEntityManagerInViewInterceptor
2021-08-22 02:55:47.744 DEBUG 17084 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Exiting from "ERROR" dispatch, status 404

I wonder if I put .jsp file in the wrong place. This is where I put the .jsp file.

enter image description here

I've been stucked for several hours. Hope someone can help me to solve the problem.

Answer 1

The GetMapping’s value is wrong. Change value to /h may work.

Changed: Try this code to instead the origin method:

@GetMapping(“/h”)
public ModelAndView init() {
    return new ModelAndView(“index”);
}