sample-spring-boot-crud-example-with-h2 example

Demo project for spring-boot-crud operation using JPA with h2 in-memory database

This project explains CRUD (Create, Read, Update, Delete) operations using spring boot and H2 in-memory database. In this app we are using Spring Data JPA for built-in methods to do CRUD operations.
@EnableJpaRepositories annotation is used on main class to Enable H2 DB related configuration, which will read properties from application.properties file.

Also, recently added Spring Reactive programming support with the help of Spring Webflux in this application. All reactive classes/interfaces are added with prefix as Reactive*.

Prerequisites

• Java
• Spring Boot
• Maven
• H2 Database
• Lombok
• Jacoco
• Azure Dev Ops

Tools

• Eclipse or IntelliJ IDEA (or any preferred IDE) with embedded Maven

• Maven (version >= 3.6.0)

• Postman (or any RESTful API testing tool)

• Swagger can be launched in Browser: http://localhost:9010/swagger-ui/index.html?configUrl=/v3/api-docs/swagger-config

• H2 Console On Browser: http://localhost:9010/h2-console

• Code Coverage: After building the projects you can find code coverage in the target path :- /sample-spring-boot-crud-example-with-h2/target/site/jacoco/index.html

For Ex: Code Coverage of StudentController looks like this:

Build and Run application

GOTO > ~/absolute-path-to-directory/sample-spring-boot-crud-example-with-h2
and try below command in terminal

mvn spring-boot:run it will run application as spring boot application

or

mvn clean install it will build application and create jar file under target directory

Run jar file from below path with given command

java -jar ~/path-to-sample-spring-boot-crud-example-with-h2/target/sample-spring-boot-crud-example-with-h2-1.0.0-SNAPSHOT

Or

run main method from SpringBootH2CRUDApplication.java as spring boot application.

Note : In SpringBootH2CRUDApplication.java class we have autowired both SportsIcon, Student and Employee repositories. If there is no record present in DB for any one of that module class (SportsIcon, Student and Employee), static data is getting inserted in DB from UtilityHelper.java class when we are starting the app for the first time.

Code Snippets

1. Maven Dependencies

   Need to add below dependencies to enable H2 DB related config in pom.xml. Lombok's dependency is to get rid of boiler-plate code.

   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-data-jpa</artifactId>
   </dependency>
   
   <!-- update -->
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-aop</artifactId>
   </dependency>
   
   <dependency>
       <groupId>com.h2database</groupId>
       <artifactId>h2</artifactId>
       <scope>runtime</scope>
   </dependency>
   
   <dependency>
       <groupId>org.projectlombok</groupId>
       <artifactId>lombok</artifactId>
       <optional>true</optional>
   </dependency>
   

   Added Reactive spring support with below dependencies in this application.

   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-webflux</artifactId>
   </dependency>
   
   <dependency>
       <groupId>io.projectreactor</groupId>
       <artifactId>reactor-test</artifactId>
       <scope>test</scope>
   </dependency>
   

2. Properties file

   Reading H2 DB related properties from application.properties file and configuring JPA connection factory for H2 database.

   src/main/resources/application.properties

   server.port=9010
   
   spring.datasource.url=jdbc:h2:mem:sampledb
   spring.datasource.driverClassName=org.h2.Driver
   spring.datasource.username=sa
   spring.datasource.password=password
   spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
   
   spring.h2.console.enabled=true
   
   #spring.data.rest.base-path=/phone
   spring.data.rest.base-default-page-size=10
   spring.data.rest.base-max-page-size=20
   
   springdoc.version=1.0.0
   springdoc.swagger-ui.path=/swagger-ui-custom.html 
   

Swagger can be launched in Browser: http://localhost:9010/swagger-ui/index.html?configUrl=/v3/api-docs/swagger-config

H2 Console On Browser: http://localhost:9010/h2-console

3. Jacoco Configuration

   Jacoco plugin is used for getting Code coverage Report, Offcial Documentation Jacoco

   pom.xml

          <plugin>
              <groupId>org.jacoco</groupId>
              <artifactId>jacoco-maven-plugin</artifactId>
              <version>0.8.5</version>
              <configuration>
                  <rules>
                      <rule implementation="org.jacoco.maven.RuleConfiguration">
                          <element>BUNDLE</element>
                          <limits>
                              <limit implementation="org.jacoco.report.check.Limit">
                                  <counter>INSTRUCTION</counter>
                                  <value>COVEREDRATION</value>
                                  <minimun>0.80</minimun>
   
                              </limit>
                          </limits>
                      </rule>
                  </rules>
              </configuration>
              <executions>
                  <execution>
                      <id>default-prepare-agent</id>
                      <goals>
                          <goal>prepare-agent</goal>
                      </goals>
                  </execution>
                  <execution>
                      <id>default-report</id>
                      <phase>verify</phase>
                      <goals>
                          <goal>report</goal>
                      </goals>
                  </execution>
              </executions>
          </plugin>
   

4. Model class

   Below are the model classes which we will store in H2 DB and perform CRUD operations.
   SportsIcon.java

   @Data
   @AllArgsConstructor
   @NoArgsConstructor
   @Builder
   @Entity
   @Table
   public class SportsIcon implements Serializable {
   
       @Id
       @GeneratedValue
       private int id;
   
       private String name;
       private String specialName;
       private String profession;
       private int age;
       private boolean olampian;
   
       // Constructor, Getter and Setter
   }
   

   Student.java

   @Data
   @AllArgsConstructor
   @NoArgsConstructor
   @Builder
   @Entity
   @Table
   public class Student implements Serializable {
   
   	@Id
   	@GeneratedValue
   	private int id;
   
   	private int rollNo;
   	private String firstName;
   	private String lastName;
   	private float marks;
   	
   }
   

   Employee.java

   @Getter
   @Setter
   @NoArgsConstructor
   @AllArgsConstructor
   @Builder
   @Entity
   @Table
   public class Employee implements Serializable {
   
       @Id
       @GeneratedValue
       private int id;
       @Column(name = "first_name")
       private String firstName;
       @Column(name = "last_name")
       private String lastName;
       private int age;
   
       @Column(name = "no_of_childrens")
       private int noOfChildrens;
       private boolean spouse;
   
       @JsonManagedReference
       @OneToOne(cascade = { 
                    CascadeType.MERGE,
                    CascadeType.PERSIST,
                    CascadeType.REMOVE
       })
       @JoinColumn(name="address")
       private Address address;
   
   
       @JsonManagedReference
       @OneToMany(fetch = FetchType.LAZY, mappedBy = "employee", 
           cascade = { 
                   CascadeType.MERGE,
                   CascadeType.PERSIST,
                   CascadeType.REMOVE
       })
       private List<PhoneNumber> phoneNumbers;
   
   
   
       @ElementCollection
       @CollectionTable(name="hobbies", joinColumns=@JoinColumn(name="id"))
       @Column(name="hobby")
       private List<String> hobbies = new ArrayList<>();
   
   }
   

   Address.java

   @Getter
   @Setter
   @NoArgsConstructor
   @AllArgsConstructor
   @Builder
   @Entity
   @Table
   public class Address implements Serializable {
   
       @Id
       @GeneratedValue
       private int id;
   
       @Column(name = "street_address")
       private String streetAddress;
       private String city;
       private String state;
       private String country;
   
       @Column(name = "postal_address")
       private String postalCode;
   
       @JsonBackReference
       @OneToOne(mappedBy="address", 
               cascade = { 
                       CascadeType.MERGE,
                       CascadeType.PERSIST,
                       CascadeType.REMOVE
               })
       private Employee employee;
   }
   

   PhoneNumber.java

   @Getter
   @Setter
   @NoArgsConstructor
   @AllArgsConstructor
   @Builder
   @Entity
   @Table
   public class PhoneNumber implements Serializable {
   
       @Id
       @GeneratedValue
       private int id;
       private String type;
       private String number;
   
   
       @JsonBackReference
       @ManyToOne(cascade= { CascadeType.ALL})
       @JoinColumn(name="employee_id")
       private Employee employee;
   
   }
   

   Update: New annotations are added in this application to print log smartly with the help of Aspect (LoggerAspect class from aop package).

   @LogObjectBefore - annotation created to print log before method execution
   @LogObjectAfter - annotation created to print the returned value from method

5. CRUD operation for Sports Icon

   In SportsIconController.java class, we have exposed 5 endpoints for basic CRUD operations

   • GET All Sports Manes
   • GET by ID
   • POST to store Sports Icon in DB
   • PUT to update Sports Icon
   • DELETE by ID

   @RestController
   @RequestMapping("/sports-icons")
   public class SportsIconController {
       
       @LogObjectAfter
       @GetMapping
       public ResponseEntity<SportsIconList> findAll();
   
       @LogObjectAfter
       @GetMapping("/{id}")
       public ResponseEntity<SportsIcon> findById(@PathVariable String id);
   
       @LogObjectBefore
       @LogObjectAfter
       @PostMapping
       public ResponseEntity<SportsIcon> save(@RequestBody SportsIcon sportsIcon);
   
       @LogObjectBefore
       @LogObjectAfter
       @PutMapping("/{id}")
       public ResponseEntity<SportsIcon> update(@PathVariable int id, @RequestBody SportsIcon sportsIcon);
   
       @DeleteMapping("/{id}")
       public ResponseEntity<String> delete(@PathVariable String id);
   }
   

   In SportsIconServiceImpl.java, we are autowiring above interface using @Autowired annotation and doing CRUD operation.

   
   
   

   In ReactiveSportsIconController.java class, we have exposed 5 endpoints for basic CRUD operations with spring reactive feature

   • GET All Sports Manes
   • GET by ID
   • POST to store Sports Icon in DB
   • PUT to update Sports Icon
   • DELETE by ID

   @RestController
   @RequestMapping("/reactive/sports-icon")
   public class ReactiveSportsIconController {
          
       @GetMapping(path = "/", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
       public ResponseEntity<Flux<?>> findAll();
      
       @GetMapping("/{id}")
       public ResponseEntity<SportsIcon> findById(@PathVariable String id);
      
       @PostMapping
       public ResponseEntity<SportsIcon> save(@RequestBody SportsIcon sportsIcon);
      
       @PutMapping("/{id}")
       public ResponseEntity<SportsIcon> update(@PathVariable int id, @RequestBody SportsIcon sportsIcon);
      
       @DeleteMapping("/{id}")
       public ResponseEntity<String> delete(@PathVariable String id);
   }
   

   In SportsIconRepository.java, we are extending JpaRepository<Class, ID> interface which enables CRUD related methods.

   public interface SportsIconRepository extends JpaRepository<SportsIcon, String> {
   }
   

   In EmployeeController.java class, we have exposed 5 endpoints for basic CRUD operations

   • GET All Employee
   • GET by ID
   • POST to store Employee in DB
   • PUT to update Employee
   • DELETE by ID

   @RestController
   @RequestMapping("/employees")
   public class EmployeeController {
        
       @LogObjectAfter
       @GetMapping
       public ResponseEntity<EmployeeList> findAll();
    
       @LogObjectAfter
       @GetMapping("/{id}")
       public ResponseEntity<Employee> findById(@PathVariable int id);
    
       @LogObjectBefore
       @LogObjectAfter
       @PostMapping
       public ResponseEntity<Employee> save(@RequestBody Employee employee);
    
       @LogObjectBefore
       @LogObjectAfter
       @PutMapping("/{id}")
       public ResponseEntity<Employee> update(@PathVariable int id, @RequestBody Employee employee);
    
       @DeleteMapping("/{id}")
       public ResponseEntity<String> delete(@PathVariable int id);
   }
   

   In EmployeeRepository.java, we are extending JpaRepository<Class, ID> interface which enables CRUD related methods.

   public interface EmployeeRepository extends JpaRepository<Employee, Integer> {
   }
   

   In SportsIconServiceImpl.java, we are autowiring above interface using @Autowired annotation and doing CRUD operation.

6. JPA And Query operation for Employee

   In StudentController.java class JPA related operations.

API Endpoints

• Sports Man CRUD Operations

  GET Mapping http://localhost:9010/sports-icon - Get all Sports Manes

  GET Mapping http://localhost:9010/sports-icon/1 - Get Sports Man by ID

  POST Mapping http://localhost:9010/sports-icon - Add new Sports Man in DB

  Request Body

     {
         "name": "Kohli",
         "specialName": "King Kohli",
         "profession": "Cricket",
         "age": 33,
         "olampian": false
     }
  

  PUT Mapping http://localhost:9010/sports-icon/3 - Update existing Sports Man for given ID

  Request Body

     {
         "id": "3"
         "name": "Kohli",
         "specialName": "King Kohli",
         "profession": "Cricket",
         "age": 33,
         "olampian": false
     }
  

  DELETE Mapping http://localhost:9010/sports-icon/4 - Delete Sports Man by ID

• Reactive Sports Man CRUD Operations

  GET Mapping http://localhost:9010/reactive/sports-icon - Get all Sports Manes

  (Try above endpoint in Chrome to see magic, Postman currently not supporting reactive programming)

  GET Mapping http://localhost:9010/reactive/sports-icons/1 - Get Sports Icon by ID

  POST Mapping http://localhost:9010/reactive/sports-icons - Add new Sports Icon in DB

  Request Body

     {
          "name": "Kohli",
          "specialName": "King Kohli",
          "profession": "Cricket",
          "age": 33,
          "olampian": false
     }
  

  PUT Mapping http://localhost:9010/reactive/sports-icons/3 - Update existing Sports Man for given ID

  Request Body

     {
         "id": "3"
         "name": "Kohli",
         "specialName": "King Kohli",
         "profession": "Cricket",
         "age": 33,
         "olampian": false
     }
  

  DELETE Mapping http://localhost:9010/reactive/sports-icons/4 - Delete Sports Man by ID

• Student Get Operations using JPA

  GET Mapping http://localhost:9010/students - Get all Employees

  GET Mapping http://localhost:9010/students/2 - Get Student by ID

  Request Body

  {
      "rollNo": 20,
      "firstName": "Santhosh",
      "lastName": "M V",
      "marks": 1000
  }