HTTP Method-Specific Request Mapping Annotations

@PostMapping

Constrains a handler method to accept only POST requests. All attributes mirror those available in @RequestMapping.

@PostMapping("/submit-user")
public String handleUserSubmission() {
    return "redirect:/confirmation.jsp";
}

@GetMapping

Limits a handler method to respond exclusive to GET requests, sharing all valid attributes with @RequestMapping.

@GetMapping("/user-details")
public String fetchUserProfile() {
    return "forward:/profile-display.jsp";
}

Composite Controller Annotation

@RestController

Applied at the class level, this annotation combines @Controller and @ResponseBody, eliminating the need to mark every handler method with @ResponseBody for direct data serialization to HTTP responses (e.g., JSON, XML). Attributes match those of @Controller.

@RestController
public class ProductController {
    // All methods automatically serialize return values to response body
}

JSON Data Processing Annotations

@JsonFormat

Configures formatting for date/time fields when converting Java objects to JSON responses.

• pattern: Defines the desired date/time string format
• timezone: Adjusts for timezone offsets (critical when dealing with UTC-based dates)

@DateTimeFormat(pattern = "dd/MM/yyyy")
@JsonFormat(pattern = "dd/MM/yyyy", timezone = "Asia/Shanghai")
private Date orderDate;

@RequestBody

Binds the raw JSON content of an HTTP request body directly to a Java object, skipping standard form paramter parsing. GET requests do not include a request body, so this annotation is incompatible unless required is explicitly set to false.

• required: Specifies whether a request body is mandatory (defaults to true) Frontend AJAX Example (Simplified ES6+):

window.addEventListener('DOMContentLoaded', () => {
    const formData = { username: "lisi", passcode: "secure456" };
    const jsonString = JSON.stringify(formData);
    fetch('/parse-json-body', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: jsonString
    });
});

Backend Handler Example:

@RequestMapping("/parse-json-body")
public String processJsonPayload(@RequestBody(required = false) Customer customer) {
    System.out.println(customer);
    return "dashboard";
}

Cross-Origin Resource Sharing Annotation

@CrossOrigin

Resolves cross-domain AJAX request restrictions enforced by browsers’ same-origin policy (which blocks scripts from different protocols, hosts, or ports from interacting).

• origins: Lists allowed origin domains/IPs
• maxAge: Sets the maximum duration (in seconds) for preflight response caching

@CrossOrigin(origins = "https://external-shop.com", maxAge = 1800)
@RestController
@RequestMapping("/inventory")
public class StockController {
    @GetMapping("/{productId}")
    public StockItem getStockInfo(@PathVariable Long productId) { return new StockItem(); }
}