spring boot application running but endpoint throwing 404

Question

I was trying my hand at writing a sample Spring Boot application.

My initial thought was it's an easy example to follow and write but I am not able to print a simple statement upon hitting my endpoint.

I don't want to use any view (HTML,JSP etc) right now as I want to learn the backend first.

I have followed:

• Getting Started

• Spring Boot Guide

However, still stuck after a whole day of googling.

So let me reiterate the steps, I did.

1. Initialized a spring boot project from spring.io and downloaded zip.
2. Extracted the zip and imported it into Eclipse.
3. Configured a Rest Controller with an endpoint to just print a hello world statement.
4. Tomcat 9.0.56 is present on my system.
5. Running TodoApplication as Java application or Spring boot.
6. URL I am hitting is http://localhost:8080/greet

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloWorldController {
    @GetMapping("/greet")
    public String sayHelloWorld() {
        return "Hello World";
    }
}

Spring Boot Application:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class TodoApplication {

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

}

pom 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>2.6.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.sample</groupId>
    <artifactId>todo</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <name>todo</name>
    <description>Back-end for To DO App</description>

    <properties>
        <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>
    </dependencies>

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

After navigating greet URL:

Got the following exception at console:

Answer 1

I found yet one more way to get obtain a 404 with Eclipse, Spring Boot hello world application, and Maven. If you choose to 'Run on Server' or Maven install, that won't work. As the answer by Sengar already indicates, Run as, Maven Configuration, with the goal set to spring-boot:run, that will work. This answer is only to say that 'Run as Java Application' also works. But more importantly, 'Run on Server' won't, even though the war is exploded in the .metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/ directory.

Answer 2

So the solution as pointed out by xerx593 is below:

1. Make sure to select packaging as war/jar in https://start.spring.io/.
2. Import the zip file.
3. Add your controller class in same or child package of SpringBootApplication, refer this for more info https://docs.spring.io/spring-boot/docs/current/reference/html/using.html#using.structuring-your-code.
4. Open terminal and change directory to working folder.
5. Run mvn spring-boot:run if using maven.
6. Hit the endpoint for example http://localhost:8080/greet or curl request.

Also I have noticed that 8080 port is listening but spring boot fails to register on it, in this case set

server.port = port other than 8080 

in application.properties.