@RequestMapping

Establishes the routing configuration between incoming HTTP requests and specific controller methods. It functions at both the class and method scopes.

• Class Scope: Sets the primary URL prefix for the entire controller. If omitted, routes resolve from the application root. When defined, it must start with a forward slash (/).
• Method Scope: Appends a secondary path to the class prefix, completing the endpoint URI.
• Configuration Attributes:
  • value / path: Defines the exact URL pattern to match.
  • method: Restricts the handler to specific HTTP verbs (e.g., RequestMethod.GET, RequestMethod.POST).
  • params: Filters invocations based on query parameters. Supports exact key-value matching.
  • headers: Narrows mapping eligibility by inspecting specific HTTP headers in the request.

@RequestParam

Maps named query parameters or form submission fields directly to method arguments in the controller.

• value: Specifies the exact parameter name expected in the HTTP request.
• required: Boolean indicator dictating if the parameter is mandatory. Defaults to true, which triggers a client error if missing. Setting it to false allows optional submission.

@Controller
@RequestMapping("/api/accounts")
public class AccountLookupHandler {
    @RequestMapping("/verify")
    public String processAccountQuery(@RequestParam("user_handle") String loginId, 
                                      @RequestParam(value = "is_active", required = false) Boolean isActive) {
        System.out.println("Verifying handle: " + loginId + " | Active Status: " + isActive);
        return "verificationResult";
    }
}

@PathVariable

RESTful design principles advocate for resourec-based URIs where identifiers are embedded directly into the path rather than passed as query strings. @PathVariable extracts these dynamic URI segments and binds them to method parameters, a core capability introduced in Spring 3.0 for robust REST support.

• value: Corresponds to the placeholder name enclosed in braces within the mapped URL pattern (e.g., /orders/{orderId}).
• required: Enforces the presence of the URI segment.

@Controller
@RequestMapping("/warehouse")
public class InventoryRoutingController {
    @RequestMapping("/stock/{zoneCode}/{skuNumber}")
    public String locateInventory(@PathVariable("zoneCode") String storageLocation, 
                                  @PathVariable(value = "skuNumber", required = true) Long itemReference) {
        System.out.println("Scanning Zone: " + storageLocation);
        System.out.println("Tracking SKU: " + itemReference);
        return "stockSummary";
    }
}

@RequestHeader

Retrieves specific metadata from the HTTP request headers and injects it into the controller method.

• value: Targets a particular header field (e.g., Accept-Language, Authorization).
• required: Determines whether the framework should fail if the specified header is absent.

@Controller
@RequestMapping("/diagnostics")
public class NetworkInspectorController {
    @RequestMapping("/analyze-client")
    public String captureNetworkHeaders(@RequestHeader(value = "X-Forwarded-For", required = false) String proxyAddress) {
        System.out.println("Client Proxy Origin: " + proxyAddress);
        return "diagnosticReport";
    }
}

@CookieValue

Extracts stored HTTP cookie data and passes it as a method parameter within the controller layer.

• value: Identifies the specific cookie key to retrieve.
• required: Specifies if the cookie must be present in the browser request.

@Controller
@RequestMapping("/analytics")
public class SessionTrackerController {
    @RequestMapping("/track-visit")
    public String logUserCookie(@CookieValue(name = "VISITOR_ID", required = false) String uniqueToken) {
        System.out.println("Logging visitor token: " + uniqueToken);
        return "trackingConfirmation";
    }
}