CODEWITHSUNDEEP
javaspring-boot
aer-der
aer-der

Reputation: 113

Simple spring boot application not works

I have created very simple spring boot application. But it dose not return the expected output. I have mentioned tried code below.

Main:

package com.example.practice;

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

@SpringBootApplication
public class DemoApplication {

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

}

Controller:

package com.example.controller;

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

@RestController
@RequestMapping("/api")
public class ControllerClass {
    
    
    @GetMapping("/all")
    public String getAllUsers() {
        return "get All users";
    }

}

Properties:

server.port=8090

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>2.3.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.practice</groupId>
    <artifactId>practice</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Practice project for Spring Boot</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-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </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>
    </dependencies>

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

</project>

I tried in my browser by using this endpoint: http://localhost:8090/api/all

expected output:

get All users

current output:

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

Sun Nov 01 00:44:41 IST 2020
There was an unexpected error (type=Not Found, status=404).
No message available

What is the wrong I have done in my code. I am new to spring boot. Please help me to solve this problem. Thank you.

Upvotes: 0

Views: 1036

Answers (2)

nkrivenko
nkrivenko

Reputation: 1271

This can be the problem with packages of classes.

Make sure your ControllerClass is in the subpackage of DemoApplication (for example, DemoApplication is in org.example package and controller is in org.example.controllers package) or use @SpringBootApplication(scanBasePackages = "package.with.your.controller")

The problem is, the @SpringBootApplication annotation consists of:

@Configuration
@EnableAutoConfiguration
@ComponentScan

@ComponentScan here is without arguments, so according to docs, scanning will occur from the package of the class that declares this annotation. It will scan com.example.practice and subpackages, but not com.example.controllers.

Upvotes: 1

Ishikawa Yoshi
Ishikawa Yoshi

Reputation: 1779

Try to use this

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

@RestController
@RequestMapping("/api")
public class ControllerClass {
    
    
    @GetMapping("/all")
    public ResponseEntity<String> getAllUsers() {
        return new ResponseEntity<>("get All users",HttpStatus.OK);
    }

}

Upd. It looks that you have also different packages

package com.example.practice;
package com.example.controller;

and @SpringBootApplication can't autoscan your beans. There are two ways to resolve it:

  1. Move DemoApplication class to next path com.example this necessary for spring boot to autoscan beans in packages below.
  2. You need to add additional annotation @ComponentScan(“com.example”) to your DemoApplication

Upvotes: 0

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