What are the Differences Between @RequestParam and @PathVariable in Handling Special Characters?

What is the difference between @RequestParam and @PathVariable in Spring, particularly regarding the handling of special characters?

@GetMapping("/example?name={name}") public ResponseEntity<String> handleRequest(@RequestParam String name) { return ResponseEntity.ok(name); }

In Spring, both @RequestParam and @PathVariable are used to extract values from the URL, but they serve different purposes and behave differently with special characters. Here’s a detailed breakdown of each annotation.

@GetMapping("/example/{input}") public ResponseEntity<String> handlePathVariable(@PathVariable String input) { return ResponseEntity.ok(input); }

Causes

• @RequestParam is used to extract query parameters from the URL, such as those following a '?' in the request string.
• @PathVariable is used to extract template variables from the URI path, which are defined within the URL mapping.

Solutions

• When handling special characters, @RequestParam typically decodes them (e.g., '+' becomes ' ' for spaces). This is because query parameters are URL encoded, and the framework handles this decoding automatically.
• @PathVariable does not perform such decoding; a '+' remains a '+' unless explicitly handled in the code.

Mistake: Assuming that @PathVariable will decode special characters similarly to @RequestParam.

Solution: Always verify how the URL template is defined and how special characters are passed in the URL.

Mistake: Using @RequestParam for URL path variables instead of @PathVariable.

Solution: Use @PathVariable when your intent is to extract values from the URI path.