spring-boot-h2-crud

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*.

Deployed this application on heroku server, all endpoints are available on

https://spring-boot-h2-crud.herokuapp.com/

Prerequisites

• Java
• Spring Boot
• Maven
• H2 Database
• Lombok

Tools

• Eclipse or IntelliJ IDEA (or any preferred IDE) with embedded Maven
• Maven (version >= 3.6.0)
• Postman (or any RESTful API testing tool)

Build and Run application

GOTO > ~/absolute-path-to-directory/spring-boot-h2-crud
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-spring-boot-h2-crud/target/spring-boot-h2-crud-0.0.1-SNAPSHOT.jar

Or

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

Note : In SpringBootH2CRUDApplication.java class we have autowired both SuperHero, Student and Employee repositories. If there is no record present in DB for any one of that module class (SuperHero, Student and Employee), static data is getting inserted in DB from HelperUtil.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=8088
   
   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 
   

3. Model class

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

   @Data
   @AllArgsConstructor
   @NoArgsConstructor
   @Builder
   @Entity
   @Table
   public class SuperHero implements Serializable {
   
       @Id
       @GeneratedValue
       private int id;
   
       private String name;
       private String superName;
       private String profession;
       private int age;
       private boolean canFly;
   
       // 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

4. CRUD operation for Super Heroes

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

   • GET All Super Heroes
   • GET by ID
   • POST to store Super Hero in DB
   • PUT to update Super Hero
   • DELETE by ID

   @RestController
   @RequestMapping("/super-hero")
   public class SuperHeroController {
       
       @LogObjectAfter
       @GetMapping
       public ResponseEntity<List<?>> findAll();
   
       @LogObjectAfter
       @GetMapping("/{id}")
       public ResponseEntity<?> findById(@PathVariable String id);
   
       @LogObjectBefore
       @LogObjectAfter
       @PostMapping
       public ResponseEntity<?> save(@RequestBody SuperHero superHero);
   
       @LogObjectBefore
       @LogObjectAfter
       @PutMapping("/{id}")
       public ResponseEntity<?> update(@PathVariable int id, @RequestBody SuperHero superHero);
   
       @DeleteMapping("/{id}")
       public ResponseEntity<?> delete(@PathVariable String id);
   }
   

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

   
   
   

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

   • GET All Super Heroes
   • GET by ID
   • POST to store Super Hero in DB
   • PUT to update Super Hero
   • DELETE by ID

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

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

   public interface SuperHeroRepository extends JpaRepository<SuperHero, 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<List<?>> findAll();
    
       @LogObjectAfter
       @GetMapping("/{id}")
       public ResponseEntity<?> findById(@PathVariable int id);
    
       @LogObjectBefore
       @LogObjectAfter
       @PostMapping
       public ResponseEntity<?> save(@RequestBody Employee employee);
    
       @LogObjectBefore
       @LogObjectAfter
       @PutMapping("/{id}")
       public ResponseEntity<?> update(@PathVariable int id, @RequestBody Employee employee);
    
       @DeleteMapping("/{id}")
       public ResponseEntity<?> 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 SuperHeroServiceImpl.java, we are autowiring above interface using @Autowired annotation and doing CRUD operation.

5. JPA And Query operation for Employee

   In StudentController.java class JPA related operations.

API Endpoints

• Super Hero CRUD Operations

  GET Mapping http://localhost:8088/super-hero - Get all Super Heroes

  GET Mapping http://localhost:8088/super-hero/1 - Get Super Hero by ID

  POST Mapping http://localhost:8088/super-hero - Add new Super Hero in DB

  Request Body

     {
         "name": "Tony",
         "superName": "Iron Man",
         "profession": "Business",
         "age": 50,
         "canFly": true
     }
  

  PUT Mapping http://localhost:8088/super-hero/3 - Update existing Super Hero for given ID

  Request Body

     {
         "id": "3"
         "name": "Tony",
         "superName": "Iron Man",
         "profession": "Business",
         "age": 50,
         "canFly": true
     }
  

  DELETE Mapping http://localhost:8088/super-hero/4 - Delete Super Hero by ID

• Reactive Super Hero CRUD Operations

  GET Mapping http://localhost:8088/reactive/super-hero - Get all Super Heroes

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

  GET Mapping http://localhost:8088/reactive/super-hero/1 - Get Super Hero by ID

  POST Mapping http://localhost:8088/reactive/super-hero - Add new Super Hero in DB

  Request Body

     {
         "name": "Tony",
         "superName": "Iron Man",
         "profession": "Business",
         "age": 50,
         "canFly": true
     }
  

  PUT Mapping http://localhost:8088/reactive/super-hero/3 - Update existing Super Hero for given ID

  Request Body

     {
         "id": "3"
         "name": "Tony",
         "superName": "Iron Man",
         "profession": "Business",
         "age": 50,
         "canFly": true
     }
  

  DELETE Mapping http://localhost:8088/reactive/super-hero/4 - Delete Super Hero by ID

• Student Get Operations using JPA

  GET Mapping http://localhost:8088/student-jpa - Get all Employees

  GET Mapping http://localhost:8088/student-jpa/2 - Get Student by ID

  GET Mapping http://localhost:8088/student-jpa/firstName/Rahul - Get All Student with firstname as Rahul

  GET Mapping http://localhost:8088/student-jpa/one-by-firstName/Rahul - Get ONE Student with firstname as Rahul

  GET Mapping http://localhost:8088/student-jpa/firstName-like/Rahul - Get All Student which contains Rahul in their firstname

  GET Mapping http://localhost:8088/student-jpa/one-by-lastName/Ghadage - Get ONE Student with lastname as Ghadage

  GET Mapping http://localhost:8088/student-jpa/marks-greater-than/100 - Get All Student whose marks is grater than 100

  POST Mapping http://localhost:8088/student-jpa/get-by-condition - Get All Student with multiple condition

  Request Body

  {
      "rollNo": 10,
      "firstName": "Rahul",
      "lastName": "Ghadage",
      "marks": 950
  }