How many ways we can get parameter value in spring boot controller? - 4

Roman Sarker
In Spring Boot, we can get parameter values in a controller method in various ways depending on the type of parameter and its source. 
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Here are several common ways to retrieve parameter values in spring boot controller method:
  1. Path Variables : @PathVariable
  2. Request Parameters : @RequestParam
  3. Request Body : @RequestBody
  4. Request Headers : @RequestHeader
  5. Cookie Values : @CookieValue
  6. Matrix Variables : @MatrixVariable
  7. Form Data : @ModelAttribute
  8. File Uploads : @RequestParam with MultipartFile
  9. Servlet API : HttpServletRequest and HttpServletResponse
  10. Session Attributes : HttpSession
  11. Spring Security Principal : Principal

1. Path Variables
Path variables are part of the URL path.
@GetMapping("/user/{id}")
public ResponseEntity<User> getUserById(@PathVariable("id") Long id) {
    // Use the id parameter
}

2. Request Parameters
Request parameters are typically used in query strings. Like getting employee's information with employee ID numbers.
@GetMapping("/search")
public ResponseEntity<List<User>> searchUsers(@RequestParam("id") String empId) {
    // Use the empId parameter
}

3. Request Body
Request bodies are used to send complex data in a request. Typically receive JSON data to save/update.
@PostMapping("/user")
public ResponseEntity<User> createUser(@RequestBody User user) {
    // Use the user object
}

4. Request Headers
Request headers are additional information sent with the request. Like Authorization key or Token.
@GetMapping("/user")
public ResponseEntity<User> getUser(@RequestHeader("Authorization") String authHeader) {
    // Use the authHeader
}

5. Cookie Values
Cookies can be used to store small pieces of data on the client side.
@GetMapping("/cookie")
public ResponseEntity<String> getCookieValue(@CookieValue("sessionId") String sessionId) {
    // Use the sessionId cookie
}

6. Matrix Variables
Matrix variables are a way to pass parameters in the path segment.
@GetMapping("/user/{id}")
public ResponseEntity<User> getUserById(@PathVariable("id") Long id, @MatrixVariable("name") String name) {
    // Use the id and name parameters
}

7. Form Data
Form data is used for form submissions. Specially use for Java EE Applications.
@PostMapping("/submit")
public ResponseEntity<String> submitForm(@ModelAttribute Form form) {
    // Use the form data
}

8. File Uploads
File uploads are typically used for uploading files.
@PostMapping("/upload")
public ResponseEntity<String> handleFileUpload(@RequestParam("file") MultipartFile file) {
    // Use the uploaded file
}

9. Servlet API
we can access raw HTTP request and response objects.
@GetMapping("/servlet")
public ResponseEntity<String> servletApiExample(HttpServletRequest request, HttpServletResponse response) {
    String param = request.getParameter("param");
    // Use the request and response objects
}

10. Session Attributes
Session attributes are stored in the session scope.
@GetMapping("/session")
public ResponseEntity<String> sessionExample(HttpSession session) {
    String attribute = (String) session.getAttribute("attribute");
    // Use the session attribute
}

11. Spring Security Principal
we can access the authenticated user details.
@GetMapping("/principal")
public ResponseEntity<String> principalExample(Principal principal) {
    String username = principal.getName();
    // Use the principal
}

Using these annotations and objects, we can handle a wide variety of request parameters and data in our Spring Boot controller methods. In the next blog, we will see practically the most useful ways to get parameters.


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Roman Sarker

Posted by Roman Sarker

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