spring_boot_framework.md

🌱 Spring Annotations

@Repository :

• Class Level Annotation
• It can reach the database and do all the operations.
• It make the connection between the database and the business logic.
• DAO is a repository.
• It is a marker interface.

@Repository
public class TestRepo{
   public void add(){
      System.out.println("Added");
   }
}

@Service :

• Class Level Annotation
• It is a marker interface.
• It is a business logic.
• It is a service layer.
• It used to create a service layer.

@Service
public class TestService{
   public void service1(){
      //business code (iş kodları)
   }
}

---

@Autowired :

• Field Level Annotation
• It is used to inject the dependency.
• It is used to inject the object.
• It is used to inject the object reference.
• Dependency Injection is a design pattern.

public class Brand{
   private int id;
   private String name;

   @Autowired
   public Brand(int id, String name){
     this.id = id;
     this.name = name;
   }
}

---

@Controller :

• Class Level Annotation
• It is a marker interface.
• It is a controller layer.
• It is used to create a controller layer.
• It use with @RequestMapping annotation.

@Controller
@RequestMapping("/api/brands")
public class BrandsController{
   @GetMapping("/getall")
   public Employee getAll(){
       return brandService.getAll();
   }
}

---

@RequestMapping :

• Method Level Annotation
• It is used to map the HTTP request with specific method.

@Controller
@RequestMapping("/api/brands")
public class BrandsController{
   @GetMapping("/getall")
   public Employee getAll(){
       return brandService.getAll();
   }
}

---

@GetMapping :

• Method Level Annotation
• It is used to map the HTTP GET request with specific method.
• It is used to get the data.
• It is used to read the data.

  @GetMapping("/getall")
  public Employee getAll(){
      return brandService.getAll();
  }

---

@PostMapping :

• Method Level Annotation
• It is used to map the HTTP POST request with specific method.
• It is used to add the data.
• It is used to create the data.

  @PostMapping("/add")
  public void add(@RequestBody Brand brand){
      brandService.add(brand);
  }

---

@PutMapping :

• Method Level Annotation
• It is used to map the HTTP PUT request with specific method.
• It is used to update the data.

  @PutMapping("/update")
  public void update(@RequestBody Brand brand){
      brandService.update(brand);
  }

---

@DeleteMapping :

• Method Level Annotation
• It is used to map the HTTP DELETE request with specific method.
• It is used to delete the data.

  @DeleteMapping("/delete")
  public void delete(@RequestBody Brand brand){
      brandService.delete(brand);
  }

---

@PathVariable :

• Method Level Annotation
• It is used to get the data from the URL.
• It is the most suitable for RESTful web service that contains a path variable.

  @GetMapping("/getbyid/{id}")
  public Brand getById(@PathVariable int id){
      return brandService.getById(id);
  }

---

@RequestBody:

• It is used to get the data from the request body.

• It is used to get the data from the HTTP request.

• It is used to get the data from the HTTP request body.

  @PostMapping("/add")
  public void add(@RequestBody Brand brand){
      brandService.add(brand);
  }

---

@RequestParam:

• It is used to get the data from the URL.
• It is used to get the data from the URL query parameters.
• It is also known as query parameter.

@GetMapping("/getbyid")
public Brand getById(@RequestParam int id){
    return brandService.getById(id);
}

---

@RestController:

• Class Level Annotation
• It is a marker interface.
• It is a controller layer.
• It is used to create a controller layer.
• It use with @RequestMapping annotation.
• It is a combination of @Controller and @ResponseBody annotations.
• @RestController annotation is explained with @ResponseBody annotation.
• @ResponseBody eliminates the need to add a comment to every method.

@RestController
@RequestMapping("/api/brands")
public class BrandsController{
   @GetMapping("/getall")
   public Employee getAll(){
       return brandService.getAll();
   }
}

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