cant connect to mysql databse using spring boot

Question

When I am hitting http://localhost:8080/pjt/samples in Postman for json data, it shows the following error.

{
    "timestamp": "2020-05-17T10:54:26.705+0000",
    "status": 404,
    "error": "Not Found",
    "message": "No message available",
    "path": "/pjt/samples"
}

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>2.2.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>samplepjt</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>samplepjt</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-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </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>

Model

package model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "samples")
public class Sample {
    private Long id ;
    private String name;
    private String city;
    
    public Sample(String name, String city) {
        this.name = name;
        this.city = city;
    }
    
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    
    @Column(name = "name", nullable = false)
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    
    @Column(name = "city", nullable = false)
    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }
    
    @Override
    public String toString() {
        return "Sample [id=" + id + ",name=" + name + ", city=" + city +  "]";
    }
}

Repository

package repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import model.Sample;

@Repository
public interface SampleRepository  extends JpaRepository<Sample,Long>{

}

Controller

package controller;

import java.util.List;
import javax.validation.Valid;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import model.Sample;
import repository.SampleRepository;

@RestController
@RequestMapping("/pjt")
public class SampleController {
    @Autowired
    private SampleRepository sampleRepository;
    
    @PostMapping("/samples")
    public Sample createSample(@Valid @RequestBody Sample sample) {
        return sampleRepository.save(sample);
    }
     
    @GetMapping("/samples")
        public List<Sample> getAllSample() {
            return sampleRepository.findAll();
        }
    }
}

Main class and function

package com.example.demo;

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

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

application.properties

spring.datasource.url = jdbc:mysql://localhost:3306/sampledb?useSSL=false
spring.datasource.username = root
spring.datasource.password = dali

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.hibernate.ddl-auto = update

Log output

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.7.RELEASE)


2020-05-17 16:47:56.159  INFO 3688 --- [           main] com.example.demo.SamplepjtApplication    : No active profile set, falling back to default profiles: default<br />
2020-05-17 16:47:58.395  INFO 3688 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.<br />
2020-05-17 16:47:58.476  INFO 3688 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 49ms. Found 0 JPA repository interfaces.<br />
2020-05-17 16:48:00.119  INFO 3688 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8081 (http)<br />
2020-05-17 16:48:00.142  INFO 3688 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]<br />
2020-05-17 16:48:00.143  INFO 3688 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.34]<br />
2020-05-17 16:48:00.496  INFO 3688 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext<br />
2020-05-17 16:48:00.497  INFO 3688 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 4199 ms<br />
2020-05-17 16:48:00.980  INFO 3688 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [name: default]<br />
2020-05-17 16:48:01.156  INFO 3688 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate ORM core version 5.4.15.Final<br />
2020-05-17 16:48:01.579  INFO 3688 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.1.0.Final}<br />
2020-05-17 16:48:01.898  INFO 3688 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...<br />
2020-05-17 16:48:02.714  INFO 3688 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.<br />
2020-05-17 16:48:02.771  INFO 3688 --- [           main] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.MySQL5InnoDBDialect<br />
2020-05-17 16:48:03.635  INFO 3688 --- [           main] o.h.e.t.j.p.i.JtaPlatformInitiator       : HHH000490: Using JtaPlatform implementation:[org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]<br />
2020-05-17 16:48:03.660  INFO 3688 --- [           main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'<br />
2020-05-17 16:48:04.042  WARN 3688 --- [           main] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning<br />
2020-05-17 16:48:04.388  INFO 3688 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'<br />
2020-05-17 16:48:04.845  INFO 3688 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8081 (http) with context path ''<br />
2020-05-17 16:48:04.849  INFO 3688 --- [           main] com.example.demo.SamplepjtApplication    : Started SamplepjtApplication in 9.906 seconds (JVM running for 12.757)<br />
2020-05-17 16:48:13.367  INFO 3688 --- [nio-8081-exec-2] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'<br />
2020-05-17 16:48:13.369  INFO 3688 --- [nio-8081-exec-2] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'<br />
2020-05-17 16:48:13.395  INFO 3688 --- [nio-8081-exec-2] o.s.web.servlet.DispatcherServlet        : Completed initialization in 25 ms

Can anyone help me to fix this issue?

Answer 1

You have to place the SampleController.java in com.example.demo.controller & SampleRepository.java in com.example.demo.repository. Or all the files should be in com.example.demo folder.

Because @SpringBootApplication has to scan all the components. Go through this doc for better understanding https://docs.spring.io/spring-boot/docs/2.0.0.RELEASE/reference/html/using-boot-structuring-your-code.html.