优化目录结构

backend/src/main/java/com/openisle/controller/GlobalExceptionHandler.java

@@ -0,0 +1,36 @@
+package com.openisle.controller;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+import com.openisle.exception.FieldException;
+import com.openisle.exception.NotFoundException;
+import com.openisle.exception.RateLimitException;
+
+import java.util.Map;
+
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+
+    @ExceptionHandler(FieldException.class)
+    public ResponseEntity<?> handleFieldException(FieldException ex) {
+        return ResponseEntity.badRequest()
+                .body(Map.of("error", ex.getMessage(), "field", ex.getField()));
+    }
+
+    @ExceptionHandler(NotFoundException.class)
+    public ResponseEntity<?> handleNotFoundException(NotFoundException ex) {
+        return ResponseEntity.status(404).body(Map.of("error", ex.getMessage()));
+    }
+
+    @ExceptionHandler(RateLimitException.class)
+    public ResponseEntity<?> handleRateLimitException(RateLimitException ex) {
+        return ResponseEntity.status(429).body(Map.of("error", ex.getMessage()));
+    }
+
+    @ExceptionHandler(Exception.class)
+    public ResponseEntity<?> handleException(Exception ex) {
+        return ResponseEntity.badRequest().body(Map.of("error", ex.getMessage()));
+    }
+}
+