Common annotations for the controller layer of springboot

In Spring Boot, the Controller layer is a component used to process HTTP requests. The following are commonly used annotations in the Controller layer:

1、@RestController

Identify a class as a controller and make it support a RESTful API. It is a combined annotation of @Controller and @ResponseBody.

@Controller injects the currently modified class into the SpringBoot IOC container, so that the class is instantiated during the process of running from the project where the class is located.
@ResponseBody Its function is short and short, it refers to the data returned by all API interfaces in this class, regardless of whether your corresponding method returns a Map or other Object, it will be returned to the client in the form of a Json string

@RestController
public class UserController {
    
    
    // Controller methods
}

2、@RequestMapping

Map HTTP requests to handler method or controller class level. Can be used in class-level annotations to define basic URL paths, and further paths can be added in method-level annotations.

@RestController
@RequestMapping("/users")
public class UserController {
    
    
    // Methods with specific request mappings
    @GetMapping("/{id}")
    public User getUserById(@PathVariable Long id) {
    
    
        // Method implementation
    }

    @PostMapping
    public User createUser(@RequestBody User user) {
    
    
        // Method implementation
    }
}

3、@GetMapping, @PostMapping, @PutMapping, @DeleteMapping, @PatchMapping

Map HTTP GET, POST, PUT, DELETE and PATCH requests to processing methods respectively.

@RestController
@RequestMapping("/users")
public class UserController {
    
    
    @GetMapping("/{id}")
    public User getUserById(@PathVariable Long id) {
    
    
        // Method implementation
    }

    @PostMapping
    public User createUser(@RequestBody User user) {
    
    
        // Method implementation
    }

    @PutMapping("/{id}")
    public User updateUser(@PathVariable Long id, @RequestBody User user) {
    
    
        // Method implementation
    }

    @DeleteMapping("/{id}")
    public void deleteUser(@PathVariable Long id) {
    
    
        // Method implementation
    }

    @PatchMapping("/{id}")
    public User partialUpdateUser(@PathVariable Long id, @RequestBody UserPartialUpdateRequest request) {
    
    
        // Method implementation
    }
}

4、@PathVariable

Used to bind the placeholder parameters in the URL path to the parameters of the processing method

@GetMapping("/users/{id}")
public User getUserById(@PathVariable Long id) {
    
    
    // Method implementation
}

5、@RequestParam

Used to bind request parameters to the parameters of the processing method. You can specify the name of the parameter, whether it is required, and a default value.

@GetMapping("/users")
public List<User> getUsersByRole(@RequestParam("role") String role) {
    
    
    // Method implementation
}

6、@RequestBody

It is used to bind the data in the request body to the parameters of the processing method, usually used to process the JSON data of the POST request.

@PostMapping("/users")
public User createUser(@RequestBody User user) {
    
    
   // Method implementation
}

7、@RequestHeader

Used to bind the information in the request header to the parameters of the processing method.

@GetMapping("/users")
public List<User> getUsersByLocale(@RequestHeader("Accept-Language") String locale) {
    
    
    // Method implementation
}

8、@ResponseBody

Return the method's return value directly as the content of the HTTP response instead of parsing it into a view.

@GetMapping("/users/{id}")
@ResponseBody
public User getUserById(@PathVariable Long id) {
    
    
    // Method implementation
}

9、@ResponseStatus

Set the HTTP status code of the response.

@DeleteMapping("/users/{id}")
@ResponseStatus(HttpStatus.NO_CONTENT)
public void deleteUser(@PathVariable Long id) {
    
    
   // Method implementation
}

10、@ModelAttribute

Used to bind request parameters to a model object and make it accessible in the view.

@GetMapping("/users/{id}")
public String getUserDetails(@PathVariable Long id, @ModelAttribute("message") String message) {
    
    
    // Method implementation
}

11、@Valid

It is used to verify the binding request parameters, and perform data verification in combination with the JSR-303 Bean Validation specification.

@PostMapping("/users")
public ResponseEntity<?> createUser(@Valid @RequestBody User user, BindingResult result) {
    
    
    if (result.hasErrors()) {
    
    
        // Handle validation errors
    }
    // Method implementation
}