feat: upgrade user management demo

src/main/java/com/example/demo/controller/UserController.java

@@ -2,6 +2,7 @@ package com.example.demo.controller;
 
 import com.example.demo.common.ApiResponse;
 import com.example.demo.dto.UserRequest;
+import com.example.demo.dto.UserStatsResponse;
 import com.example.demo.model.User;
 import com.example.demo.service.UserService;
 import jakarta.validation.Valid;
@@ -24,31 +25,38 @@ public class UserController {
         return ApiResponse.ok(userService.findAll());
     }
 
+    @GetMapping("/stats")
+    public ApiResponse<UserStatsResponse> getUserStats() {
+        return ApiResponse.ok(userService.getStats());
+    }
+
+    @GetMapping("/search")
+    public ApiResponse<List<User>> searchUsers(@RequestParam(required = false) String keyword,
+                                               @RequestParam(required = false) String name) {
+        String term = keyword != null && !keyword.isBlank() ? keyword : name;
+        return ApiResponse.ok(userService.search(term));
+    }
+
     @GetMapping("/{id}")
     public ApiResponse<User> getUserById(@PathVariable Long id) {
         return ApiResponse.ok(userService.findById(id));
     }
 
     @PostMapping
-    public ApiResponse<User> createUser(@Valid @RequestBody UserRequest req) {
-        User user = new User(null, req.name(), req.email(), req.age());
-        return ApiResponse.ok("创建成功", userService.create(user));
+    public ApiResponse<User> createUser(@Valid @RequestBody UserRequest request) {
+        User user = new User(null, request.name(), request.email(), request.age());
+        return ApiResponse.ok("User created successfully", userService.create(user));
     }
 
     @PutMapping("/{id}")
-    public ApiResponse<User> updateUser(@PathVariable Long id, @Valid @RequestBody UserRequest req) {
-        User user = new User(id, req.name(), req.email(), req.age());
-        return ApiResponse.ok("更新成功", userService.update(id, user));
+    public ApiResponse<User> updateUser(@PathVariable Long id, @Valid @RequestBody UserRequest request) {
+        User user = new User(id, request.name(), request.email(), request.age());
+        return ApiResponse.ok("User updated successfully", userService.update(id, user));
     }
 
     @DeleteMapping("/{id}")
     public ApiResponse<Void> deleteUser(@PathVariable Long id) {
         userService.delete(id);
-        return ApiResponse.ok("删除成功", null);
-    }
-
-    @GetMapping("/search")
-    public ApiResponse<List<User>> searchUsers(@RequestParam String name) {
-        return ApiResponse.ok(userService.findByName(name));
+        return ApiResponse.ok("User deleted successfully", null);
     }
 }