@Controller
@RequestMapping("/users")
public class UserController {

    // 處理 GET /users/profile?name=John
    @GetMapping("/profile")
    public String getProfile(@RequestParam String name, Model model) {
        model.addAttribute("userName", name); // 將數(shù)據(jù)傳遞給視圖
        return "userProfile"; // 對(duì)應(yīng)視圖解析器配置的模板（如 userProfile.html）
    }
}

@Controller
@RequestMapping("/api")
public class ApiController {

    // 返回 JSON 數(shù)據(jù)（需要手動(dòng)添加 @ResponseBody）
    @GetMapping("/data")
    @ResponseBody
    public User getData() {
        return new User("Alice", 30); // 自動(dòng)轉(zhuǎn)換為 JSON
    }
}

@RestController
@RequestMapping("/api")
public class UserRestController {
    @GetMapping("/user")
    public User getUser() {
        return new User("Bob", 25); // 自動(dòng)返回 JSON
    }
}

spring.mvc.view.prefix=/WEB-INF/views/  # 視圖模板前綴
spring.mvc.view.suffix=.html           # 視圖模板后綴

@Controller
@SessionAttributes("user") // 將 "user" 屬性存儲(chǔ)到會(huì)話中
public class SessionController {
    @GetMapping("/set")
    public String setSession(Model model) {
        model.addAttribute("user", new User("Alice"));
        return "sessionPage";
    }
}

@Controller
public class ErrorController {
    @ExceptionHandler(Exception.class)
    public String handleException() {
        return "errorPage"; // 異常時(shí)返回錯(cuò)誤頁(yè)面
    }
}

@PostMapping("/save")
public String saveUser(@Valid @ModelAttribute User user, BindingResult result) {
    if (result.hasErrors()) {
        return "formPage"; // 校驗(yàn)失敗返回表單
    }
    // 保存用戶...
}

@Controller
@RequestMapping("/products")
public class ProductController {
 
    // 返回視圖（需配置視圖解析器）
    @GetMapping("/list")
    public String listProducts(Model model) {
        model.addAttribute("products", productService.getAll());
        return "products/list"; // 對(duì)應(yīng) /templates/products/list.html
    }
 
    // 返回 JSON 數(shù)據(jù)
    @GetMapping("/{id}")
    @ResponseBody
    public Product getProduct(@PathVariable Long id) {
        return productService.getById(id);
    }
 
    // 處理表單提交
    @PostMapping("/save")
    public String saveProduct(@Valid @ModelAttribute Product product, BindingResult result) {
        if (result.hasErrors()) {
            return "products/form";
        }
        productService.save(product);
        return "redirect:/products/list";
    }
}

@RestController
@RequestMapping("/api/users")
public class UserRestController {
    
    @GetMapping
    public List<User> getUsers() {
        return userService.getAllUsers();
    }
    
    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.getUserById(id);
    }
    
    @PostMapping
    public User createUser(@RequestBody User user) {
        return userService.createUser(user);
    }
    
    @PutMapping("/{id}")
    public User updateUser(@PathVariable Long id, @RequestBody User user) {
        return userService.updateUser(id, user);
    }
    
    @DeleteMapping("/{id}")
    public void deleteUser(@PathVariable Long id) {
        userService.deleteUser(id);
    }
}

@RestController
@RequestMapping("/api")
@CrossOrigin(origins = "http://localhost:3000") // 支持跨域
public class UserRestController {
    
    @GetMapping("/user")
    public User getUser() {
        return new User("Bob", 25); // 自動(dòng)返回 JSON
    }
    
    // 特定方法覆蓋類級(jí)別的映射
    @GetMapping("/admin/user")
    @CrossOrigin(origins = "http://admin.example.com")
    public User getAdminUser() {
        return new User("Admin", 30);
    }
}

// 統(tǒng)一響應(yīng)結(jié)果類
public class Result<T> {
    private int code;
    private String message;
    private T data;
    
    // 構(gòu)造方法、getter 和 setter...
    
    public static <T> Result<T> success(T data) {
        Result<T> result = new Result<>();
        result.setCode(200);
        result.setMessage("success");
        result.setData(data);
        return result;
    }
}

@RestController
@RequestMapping("/api/users")
public class UserRestController {
    
    @GetMapping
    public Result<List<User>> getUsers() {
        List<User> users = userService.getAllUsers();
        return Result.success(users);
    }
    
    @GetMapping("/{id}")
    public Result<User> getUser(@PathVariable Long id) {
        User user = userService.getUserById(id);
        return Result.success(user);
    }
}

@RestController
@RequestMapping("/api/users")
public class UserRestController {
    
    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        User user = userService.getUserById(id);
        if (user == null) {
            throw new UserNotFoundException("User not found with id: " + id);
        }
        return user;
    }
}

// 全局異常處理器
@RestControllerAdvice
public class GlobalExceptionHandler {
    
    @ExceptionHandler(UserNotFoundException.class)
    public ResponseEntity<Result<String>> handleUserNotFound(UserNotFoundException e) {
        Result<String> result = new Result<>();
        result.setCode(404);
        result.setMessage(e.getMessage());
        return ResponseEntity.status(404).body(result);
    }
}

// 推薦的 RESTful 控制器結(jié)構(gòu)
@RestController
@RequestMapping("/api/v1/users")
@CrossOrigin
public class UserRestController {
    
    @Autowired
    private UserService userService;
    
    @GetMapping
    public ResponseEntity<List<User>> getAllUsers() {
        List<User> users = userService.findAll();
        return ResponseEntity.ok(users);
    }
    
    @GetMapping("/{id}")
    public ResponseEntity<User> getUserById(@PathVariable Long id) {
        return userService.findById(id)
                .map(ResponseEntity::ok)
                .orElse(ResponseEntity.notFound().build());
    }
    
    @PostMapping
    public ResponseEntity<User> createUser(@Valid @RequestBody User user) {
        User savedUser = userService.save(user);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedUser);
    }
    
    @PutMapping("/{id}")
    public ResponseEntity<User> updateUser(
            @PathVariable Long id, 
            @Valid @RequestBody User user) {
        
        return userService.update(id, user)
                .map(ResponseEntity::ok)
                .orElse(ResponseEntity.notFound().build());
    }
    
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteUser(@PathVariable Long id) {
        userService.deleteById(id);
        return ResponseEntity.noContent().build();
    }
}

@Controller
@RequestMapping("/users")
public class UserController {
    
    // 實(shí)際映射路徑為 /users
    @RequestMapping("")
    public String getUsers() {
        return "userList";
    }
    
    // 實(shí)際映射路徑為 /users/create
    @RequestMapping("/create")
    public String createUserForm() {
        return "userCreateForm";
    }
    
    // 實(shí)際映射路徑為 /users
    @RequestMapping(method = RequestMethod.POST)
    public String createUser() {
        // 創(chuàng)建用戶邏輯
        return "userCreated";
    }
}

@Controller
public class UserController {
    
    @RequestMapping("/users")
    public String getUsers() {
        return "userList";
    }
    
    @RequestMapping(value = "/users", method = RequestMethod.POST)
    public String createUser() {
        // 創(chuàng)建用戶邏輯
        return "userCreated";
    }
    
    @RequestMapping(value = "/users/{id}", method = RequestMethod.GET)
    public String getUser(@PathVariable Long id) {
        // 獲取用戶邏輯
        return "userDetail";
    }
}

@Controller
@RequestMapping("/files")
public class FileController {
    
    // 匹配 /files/anyfile.txt
    @RequestMapping("/*.txt")
    public String getTextFile() {
        return "textFileView";
    }
    
    // 匹配 /files/path/to/anyfile.json
    @RequestMapping("/**/*.json")
    public String getJsonFile() {
        return "jsonFileView";
    }
    
    // 匹配 /files/abc 或 /files/def 等
    @RequestMapping("/{fileName:^[a-z]+}")
    public String getFile(@PathVariable String fileName) {
        return "fileView";
    }
}

@Controller
public class ApiController {
    
    // 僅匹配帶有 version=2 參數(shù)的請(qǐng)求
    @RequestMapping(value = "/api/data", params = "version=2")
    public String getDataV2() {
        return "dataV2";
    }
    
    // 僅匹配 Accept 頭部為 application/json 的請(qǐng)求
    @RequestMapping(value = "/api/data", headers = "Accept=application/json")
    @ResponseBody
    public String getJsonData() {
        return "{\"data\":\"json\"}";
    }
    
    // 僅匹配 Content-Type 為 application/json 且 Accept 為 text/html 的請(qǐng)求
    @RequestMapping(value = "/api/data", 
                   consumes = "application/json", 
                   produces = "text/html")
    public String processData() {
        return "processedData";
    }
}

@Controller
@RequestMapping("/api/users")
public class UserController {
    
    // 支持 GET 和 POST 方法
    @RequestMapping(method = {RequestMethod.GET, RequestMethod.POST})
    public String handleUsers(HttpServletRequest request) {
        if ("GET".equals(request.getMethod())) {
            return "userList";
        } else {
            return "userCreated";
        }
    }
    
    // 支持所有 HTTP 方法
    @RequestMapping("/{id}")
    public String handleUser(@PathVariable Long id, HttpServletRequest request) {
        switch (request.getMethod()) {
            case "GET": return "userDetail";
            case "PUT": return "userUpdated";
            case "DELETE": return "userDeleted";
            default: return "error";
        }
    }
}

// 推薦的 RESTful 風(fēng)格
@RestController
@RequestMapping("/api/users")
public class UserController {
    
    @GetMapping
    public List<User> getUsers() {
        return userService.getAllUsers();
    }
    
    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.getUserById(id);
    }
    
    @PostMapping(consumes = "application/json")
    public User createUser(@RequestBody User user) {
        return userService.createUser(user);
    }
    
    @PutMapping("/{id}")
    public User updateUser(@PathVariable Long id, @RequestBody User user) {
        return userService.updateUser(id, user);
    }
    
    @DeleteMapping("/{id}")
    public void deleteUser(@PathVariable Long id) {
        userService.deleteUser(id);
    }
}

@GetMapping("/users/search")
public String searchUsers(@RequestParam("name") String name, 
                          @RequestParam("age") Integer age) {
    // 處理請(qǐng)求參數(shù)
    // 例如：/users/search?name=Tom&age=25
    return "userList";
}

@GetMapping("/users")
public String getUsers(@RequestParam(value = "page", defaultValue = "1") Integer page,
                       @RequestParam(value = "size", defaultValue = "10") Integer size,
                       @RequestParam(value = "sort", required = false) String sort) {
    // page 和 size 參數(shù)有默認(rèn)值，即使不傳也會(huì)有值
    // sort 參數(shù)是可選的，不傳時(shí)為 null
    return "userList";
}

@GetMapping("/users/batch")
public String batchDelete(@RequestParam("ids") Long[] ids) {
    // 處理多個(gè) ID
    // 例如：/users/batch?ids=1&ids=2&ids=3
    return "batchDeleted";
}

@GetMapping("/users/filter")
public String filterUsers(@RequestParam("tags") List<String> tags) {
    // 處理標(biāo)簽列表
    // 例如：/users/filter?tags=VIP&tags=Active
    return "filteredList";
}

// 用戶搜索條件類
public class UserSearchCriteria {
    private String name;
    private Integer age;
    private String email;
    // getter 和 setter 方法...
}

@Controller
public class UserController {
    
    // 通過(guò) @RequestParam 綁定復(fù)雜對(duì)象的屬性
    @GetMapping("/users/search")
    public String searchUsers(
            @RequestParam(required = false) String name,
            @RequestParam(required = false) Integer age,
            @RequestParam(required = false) String email,
            Model model) {
        
        UserSearchCriteria criteria = new UserSearchCriteria();
        criteria.setName(name);
        criteria.setAge(age);
        criteria.setEmail(email);
        
        List<User> users = userService.searchUsers(criteria);
        model.addAttribute("users", users);
        return "userList";
    }
}

@GetMapping("/users/page")
public String getUsersPaginated(
        @RequestParam(value = "page", defaultValue = "1") 
        @Min(1) Integer page,
        @RequestParam(value = "size", defaultValue = "10") 
        @Min(1) @Max(100) Integer size) {
    
    // 使用 Bean Validation 進(jìn)行參數(shù)驗(yàn)證
    // page 必須大于等于 1
    // size 必須在 1-100 之間
    return "userList";
}

// 推薦的參數(shù)處理方式
@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 分頁(yè)查詢
    @GetMapping
    public Page<User> getUsers(
            @RequestParam(value = "page", defaultValue = "0") int page,
            @RequestParam(value = "size", defaultValue = "20") int size,
            @RequestParam(value = "sort", defaultValue = "id") String sort) {
        
        return userService.getUsers(PageRequest.of(page, size, Sort.by(sort)));
    }
    
    // 搜索功能
    @GetMapping("/search")
    public List<User> searchUsers(
            @RequestParam(value = "keyword", required = false) String keyword,
            @RequestParam(value = "department", required = false) String department) {
        
        return userService.searchUsers(keyword, department);
    }
}

@GetMapping("/users/{id}")
public String getUser(@PathVariable("id") Long id) {
    // 處理 /users/123 這樣的請(qǐng)求
    // id 參數(shù)值為 123
    return "userDetail";
}

// 當(dāng)方法參數(shù)名與路徑變量名一致時(shí)，可以省略 value 屬性
@GetMapping("/users/{id}")
public String getUser(@PathVariable Long id) {
    return "userDetail";
}

// 多個(gè)路徑變量
@GetMapping("/users/{userId}/orders/{orderId}")
public String getOrder(@PathVariable("userId") Long userId, 
                       @PathVariable("orderId") Long orderId) {
    return "orderDetail";
}

// 混合使用路徑變量和請(qǐng)求參數(shù)
@GetMapping("/users/{userId}/orders")
public String getUserOrders(@PathVariable("userId") Long userId,
                           @RequestParam(value = "status", required = false) String status) {
    return "orderList";
}

@RestController
public class FileController {
    
    // 限制 id 只能是數(shù)字
    @GetMapping("/files/{id:\\d+}")
    public String getFile(@PathVariable Long id) {
        return "fileContent";
    }
    
    // 限制文件名格式
    @GetMapping("/images/{filename:.+\\.(jpg|png|gif)}")
    public String getImage(@PathVariable String filename) {
        return "imageContent";
    }
    
    // 日期格式約束
    @GetMapping("/events/{date:\\d{4}-\\d{2}-\\d{2}}")
    public String getEvent(@PathVariable("date") String date) {
        return "eventDetail";
    }
}

@RestController
@RequestMapping("/api")
public class ResourceController {
    
    // 處理版本化的 API
    @GetMapping("/v{version:\\d+}/users/{userId}")
    public String getUser(@PathVariable Integer version,
                         @PathVariable Long userId) {
        if (version < 2) {
            // 返回舊版本數(shù)據(jù)格式
            return "userOldFormat";
        } else {
            // 返回新版本數(shù)據(jù)格式
            return "userNewFormat";
        }
    }
    
    // 處理多級(jí)路徑
    @GetMapping("/categories/{categoryPath:.+}")
    public String getCategory(@PathVariable String categoryPath) {
        // categoryPath 可以包含多級(jí)路徑，如 "electronics/computers/laptops"
        String[] paths = categoryPath.split("/");
        return "categoryDetail";
    }
}

// 推薦的 RESTful 風(fēng)格設(shè)計(jì)
@RestController
@RequestMapping("/api")
public class UserController {
    
    // 獲取用戶信息
    @GetMapping("/users/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.getUserById(id);
    }
    
    // 獲取用戶的訂單
    @GetMapping("/users/{userId}/orders")
    public List<Order> getUserOrders(@PathVariable Long userId) {
        return orderService.getOrdersByUserId(userId);
    }
    
    // 獲取訂單詳情
    @GetMapping("/users/{userId}/orders/{orderId}")
    public Order getOrder(@PathVariable Long userId, 
                         @PathVariable Long orderId) {
        return orderService.getOrder(userId, orderId);
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 查詢所有用戶
    @GetMapping
    public List<User> getUsers() {
        return userService.getAllUsers();
    }
    
    // 根據(jù) ID 查詢用戶
    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.getUserById(id);
    }
    
    // 帶查詢參數(shù)的 GET 請(qǐng)求
    @GetMapping(params = "name")
    public List<User> getUsersByName(@RequestParam String name) {
        return userService.getUsersByName(name);
    }
}

@RestController
@RequestMapping("/api/products")
public class ProductController {
    
    // 分頁(yè)查詢
    @GetMapping
    public Page<Product> getProducts(
            @RequestParam(defaultValue = "0") int page,
            @RequestParam(defaultValue = "10") int size,
            @RequestParam(defaultValue = "name") String sortBy) {
        
        return productService.getProducts(PageRequest.of(page, size, Sort.by(sortBy)));
    }
    
    // 條件查詢
    @GetMapping("/search")
    public List<Product> searchProducts(
            @RequestParam(required = false) String keyword,
            @RequestParam(required = false) String category,
            @RequestParam(required = false) BigDecimal minPrice,
            @RequestParam(required = false) BigDecimal maxPrice) {
        
        return productService.searchProducts(keyword, category, minPrice, maxPrice);
    }
    
    // 查詢統(tǒng)計(jì)信息
    @GetMapping("/count")
    public long getProductCount() {
        return productService.count();
    }
}

@RestController
@RequestMapping("/api/data")
public class DataController {
    
    // 僅當(dāng)請(qǐng)求包含 version=2 參數(shù)時(shí)匹配
    @GetMapping(params = "version=2")
    public String getDataV2() {
        return "data version 2";
    }
    
    // 僅當(dāng)請(qǐng)求包含 format=json 參數(shù)時(shí)匹配
    @GetMapping(params = "format=json", produces = "application/json")
    @ResponseBody
    public Map<String, Object> getJsonData() {
        Map<String, Object> data = new HashMap<>();
        data.put("message", "json data");
        return data;
    }
    
    // 僅當(dāng) Accept 頭部為 text/xml 時(shí)匹配
    @GetMapping(produces = "text/xml")
    public String getXmlData() {
        return "<data>xml data</data>";
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 結(jié)合緩存注解
    @GetMapping("/{id}")
    @Cacheable(value = "users", key = "#id")
    public User getUser(@PathVariable Long id) {
        return userService.getUserById(id);
    }
    
    // 結(jié)合權(quán)限控制
    @GetMapping("/admin")
    @PreAuthorize("hasRole('ADMIN')")
    public List<User> getAllUsers() {
        return userService.getAllUsers();
    }
    
    // 異步處理
    @GetMapping("/async")
    public Callable<String> getAsyncData() {
        return () -> {
            // 模擬耗時(shí)操作
            Thread.sleep(1000);
            return "async data";
        };
    }
}

// 推薦的查詢接口設(shè)計(jì)
@RestController
@RequestMapping("/api/users")
public class UserController {
    
    @Autowired
    private UserService userService;
    
    // 基礎(chǔ)查詢
    @GetMapping
    public ResponseEntity<Page<User>> getUsers(
            @RequestParam(defaultValue = "0") @Min(0) int page,
            @RequestParam(defaultValue = "10") @Min(1) @Max(100) int size) {
        
        Page<User> users = userService.findAll(PageRequest.of(page, size));
        return ResponseEntity.ok(users);
    }
    
    // 條件查詢
    @GetMapping(params = "name")
    public ResponseEntity<List<User>> getUsersByName(
            @RequestParam String name,
            @RequestParam(defaultValue = "false") boolean exact) {
        
        List<User> users = exact ? 
                userService.findByName(name) : 
                userService.findByNameContaining(name);
        return ResponseEntity.ok(users);
    }
    
    // 統(tǒng)計(jì)查詢
    @GetMapping("/statistics")
    public ResponseEntity<Map<String, Object>> getUserStatistics() {
        Map<String, Object> statistics = userService.getStatistics();
        return ResponseEntity.ok(statistics);
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 創(chuàng)建新用戶
    @PostMapping
    public ResponseEntity<User> createUser(@RequestBody User user) {
        User savedUser = userService.save(user);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedUser);
    }
    
    // 創(chuàng)建用戶的訂單
    @PostMapping("/{userId}/orders")
    public ResponseEntity<Order> createOrder(
            @PathVariable Long userId, 
            @RequestBody Order order) {
        
        Order savedOrder = orderService.createOrder(userId, order);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedOrder);
    }
}

@Controller
@RequestMapping("/users")
public class UserController {
    
    // 處理表單提交
    @PostMapping("/register")
    public String registerUser(@ModelAttribute User user, BindingResult result) {
        if (result.hasErrors()) {
            return "registerForm";
        }
        
        userService.save(user);
        return "redirect:/users/" + user.getId();
    }
    
    // 文件上傳
    @PostMapping("/upload")
    public String handleFileUpload(@RequestParam("file") MultipartFile file,
                                  RedirectAttributes redirectAttributes) {
        
        // 處理文件上傳邏輯
        redirectAttributes.addFlashAttribute("message", 
                "文件上傳成功: " + file.getOriginalFilename());
        return "redirect:/users/status";
    }
}

@RestController
@RequestMapping("/api/data")
public class DataController {
    
    // 僅處理 JSON 格式的請(qǐng)求
    @PostMapping(consumes = "application/json")
    public ResponseEntity<String> handleJsonData(@RequestBody Map<String, Object> data) {
        // 處理 JSON 數(shù)據(jù)
        return ResponseEntity.ok("JSON data processed");
    }
    
    // 僅處理 XML 格式的請(qǐng)求
    @PostMapping(consumes = "application/xml", produces = "application/xml")
    public ResponseEntity<String> handleXmlData(@RequestBody String xmlData) {
        // 處理 XML 數(shù)據(jù)
        String response = "<response>XML data processed</response>";
        return ResponseEntity.ok(response);
    }
    
    // 僅處理表單數(shù)據(jù)
    @PostMapping(consumes = "application/x-www-form-urlencoded")
    public ResponseEntity<String> handleFormData(@RequestParam Map<String, String> formData) {
        // 處理表單數(shù)據(jù)
        return ResponseEntity.ok("Form data processed");
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 結(jié)合驗(yàn)證注解
    @PostMapping
    public ResponseEntity<User> createUser(@Valid @RequestBody User user, 
                                          BindingResult result) {
        if (result.hasErrors()) {
            return ResponseEntity.badRequest().build();
        }
        
        User savedUser = userService.save(user);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedUser);
    }
    
    // 結(jié)合事務(wù)注解
    @PostMapping("/batch")
    @Transactional
    public ResponseEntity<List<User>> createUsers(@RequestBody List<User> users) {
        List<User> savedUsers = userService.saveAll(users);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedUsers);
    }
    
    // 結(jié)合安全注解
    @PostMapping("/admin")
    @PreAuthorize("hasRole('ADMIN')")
    public ResponseEntity<User> createAdminUser(@RequestBody User user) {
        user.setRole("ADMIN");
        User savedUser = userService.save(user);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedUser);
    }
}

// 推薦的資源創(chuàng)建接口設(shè)計(jì)
@RestController
@RequestMapping("/api/users")
public class UserController {
    
    @Autowired
    private UserService userService;
    
    @PostMapping
    public ResponseEntity<User> createUser(@Valid @RequestBody User user, 
                                          HttpServletRequest request) {
        
        // 保存用戶
        User savedUser = userService.save(user);
        
        // 構(gòu)建資源 URI
        URI location = ServletUriComponentsBuilder
                .fromCurrentRequest()
                .path("/{id}")
                .buildAndExpand(savedUser.getId())
                .toUri();
        
        // 返回 201 狀態(tài)碼和 Location 頭部
        return ResponseEntity.created(location).body(savedUser);
    }
    
    // 批量創(chuàng)建
    @PostMapping("/batch")
    public ResponseEntity<List<User>> createUsers(@Valid @RequestBody List<User> users) {
        if (users.size() > 100) {
            return ResponseEntity.badRequest().build();
        }
        
        List<User> savedUsers = userService.saveAll(users);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedUsers);
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 根據(jù) ID 刪除用戶
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteUser(@PathVariable Long id) {
        userService.deleteById(id);
        return ResponseEntity.noContent().build();
    }
    
    // 條件刪除
    @DeleteMapping(params = "status")
    public ResponseEntity<Void> deleteUsersByStatus(@RequestParam String status) {
        userService.deleteByStatus(status);
        return ResponseEntity.noContent().build();
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 批量刪除用戶
    @DeleteMapping("/batch")
    public ResponseEntity<Void> deleteUsers(@RequestBody List<Long> ids) {
        userService.deleteAllById(ids);
        return ResponseEntity.noContent().build();
    }
    
    // 刪除所有用戶（謹(jǐn)慎使用）
    @DeleteMapping
    @PreAuthorize("hasRole('ADMIN')")
    public ResponseEntity<Void> deleteAllUsers() {
        userService.deleteAll();
        return ResponseEntity.noContent().build();
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 軟刪除：標(biāo)記為已刪除而不是物理刪除
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> softDeleteUser(@PathVariable Long id) {
        userService.softDelete(id);
        return ResponseEntity.noContent().build();
    }
    
    // 永久刪除
    @DeleteMapping("/{id}/permanent")
    @PreAuthorize("hasRole('ADMIN')")
    public ResponseEntity<Void> permanentDeleteUser(@PathVariable Long id) {
        userService.permanentDelete(id);
        return ResponseEntity.noContent().build();
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    // 刪除用戶及其關(guān)聯(lián)數(shù)據(jù)
    @DeleteMapping("/{id}")
    @Transactional
    public ResponseEntity<Void> deleteUserWithRelations(
            @PathVariable Long id, 
            @RequestParam(defaultValue = "false") boolean cascade) {
        
        if (cascade) {
            // 級(jí)聯(lián)刪除關(guān)聯(lián)數(shù)據(jù)
            orderService.deleteByUserId(id);
            userService.deleteById(id);
        } else {
            // 檢查是否有關(guān)聯(lián)數(shù)據(jù)
            if (orderService.existsByUserId(id)) {
                return ResponseEntity.status(HttpStatus.CONFLICT).build();
            }
            userService.deleteById(id);
        }
        
        return ResponseEntity.noContent().build();
    }
}

// 推薦的刪除接口設(shè)計(jì)
@RestController
@RequestMapping("/api/users")
public class UserController {
    
    @Autowired
    private UserService userService;
    
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteUser(
            @PathVariable Long id, 
            Authentication authentication) {
        
        // 檢查資源是否存在
        if (!userService.existsById(id)) {
            return ResponseEntity.notFound().build();
        }
        
        // 檢查權(quán)限
        if (!userService.canDelete(id, authentication)) {
            return ResponseEntity.status(HttpStatus.FORBIDDEN).build();
        }
        
        // 執(zhí)行刪除
        userService.deleteById(id);
        
        // 返回 204 狀態(tài)碼
        return ResponseEntity.noContent().build();
    }
    
    // 批量刪除
    @DeleteMapping("/batch")
    public ResponseEntity<Map<String, Object>> deleteUsers(@RequestBody List<Long> ids) {
        Map<String, Object> result = new HashMap<>();
        
        try {
            int deletedCount = userService.deleteAllById(ids);
            result.put("deletedCount", deletedCount);
            result.put("totalCount", ids.size());
            return ResponseEntity.ok(result);
        } catch (Exception e) {
            result.put("error", e.getMessage());
            return ResponseEntity.badRequest().body(result);
        }
    }
}

@Controller
@RequestMapping("/api")
public class ApiController {
    
    // 返回 JSON 數(shù)據(jù)
    @GetMapping("/user")
    @ResponseBody
    public User getUser() {
        return new User("Alice", 30); // 自動(dòng)轉(zhuǎn)換為 JSON
    }
    
    // 返回字符串?dāng)?shù)據(jù)
    @GetMapping("/message")
    @ResponseBody
    public String getMessage() {
        return "Hello, World!";
    }
    
    // 返回集合數(shù)據(jù)
    @GetMapping("/users")
    @ResponseBody
    public List<User> getUsers() {
        return Arrays.asList(new User("Alice", 30), new User("Bob", 25));
    }
}

// 等價(jià)于在每個(gè)方法上添加 @ResponseBody
@RestController  // @RestController = @Controller + @ResponseBody
@RequestMapping("/api/users")
public class UserRestController {
    
    @GetMapping
    public List<User> getUsers() {
        return userService.getAllUsers();
    }
    
    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.getUserById(id);
    }
}

@Controller
public class DataController {
    
    // 返回自定義格式的數(shù)據(jù)
    @GetMapping(value = "/data", produces = "application/json")
    @ResponseBody
    public String getJsonData() {
        return "{"name": "Alice", "age": 30}";
    }
    
    // 返回 XML 數(shù)據(jù)
    @GetMapping(value = "/data.xml", produces = "application/xml")
    @ResponseBody
    public String getXmlData() {
        return "<user><name>Alice</name><age>30</age></user>";
    }
    
    // 返回二進(jìn)制數(shù)據(jù)
    @GetMapping(value = "/image", produces = "image/png")
    @ResponseBody
    public byte[] getImage() throws IOException {
        // 返回圖片數(shù)據(jù)
        return Files.readAllBytes(Paths.get("path/to/image.png"));
    }
}

@Controller
public class UserController {
    
    // 使用 ResponseEntity 提供更多控制
    @GetMapping("/user/{id}")
    @ResponseBody
    public ResponseEntity<User> getUser(@PathVariable Long id) {
        User user = userService.getUserById(id);
        if (user != null) {
            return ResponseEntity.ok(user);
        } else {
            return ResponseEntity.notFound().build();
        }
    }
    
    // 帶自定義頭部的響應(yīng)
    @PostMapping("/user")
    @ResponseBody
    public ResponseEntity<User> createUser(@RequestBody User user) {
        User savedUser = userService.save(user);
        
        return ResponseEntity
                .created(URI.create("/api/user/" + savedUser.getId()))
                .header("X-Custom-Header", "CustomValue")
                .body(savedUser);
    }
}

// 推薦的 RESTful API 設(shè)計(jì)
@RestController
@RequestMapping("/api/users")
public class UserController {
    
    @Autowired
    private UserService userService;
    
    // 查詢所有用戶
    @GetMapping(produces = "application/json")
    public ResponseEntity<List<User>> getUsers() {
        List<User> users = userService.findAll();
        return ResponseEntity.ok(users);
    }
    
    // 根據(jù) ID 查詢用戶
    @GetMapping(value = "/{id}", produces = "application/json")
    public ResponseEntity<User> getUser(@PathVariable Long id) {
        return userService.findById(id)
                .map(ResponseEntity::ok)
                .orElse(ResponseEntity.notFound().build());
    }
    
    // 創(chuàng)建用戶
    @PostMapping(consumes = "application/json", produces = "application/json")
    public ResponseEntity<User> createUser(@Valid @RequestBody User user, 
                                          HttpServletRequest request) {
        
        User savedUser = userService.save(user);
        
        // 構(gòu)建資源 URI
        URI location = ServletUriComponentsBuilder
                .fromContextPath(request)
                .path("/api/users/{id}")
                .buildAndExpand(savedUser.getId())
                .toUri();
        
        return ResponseEntity.created(location).body(savedUser);
    }
}

@Service
public class UserService {
    
    public User queryById(Long id) {
        return userMapper.findById(id);
    }
    
    public List<User> getAllUsers() {
        return userMapper.findAll();
    }
    
    public User saveUser(User user) {
        return userMapper.save(user);
    }
}

@Service("userService")
public class UserServiceImpl implements UserService {
    
    @Override
    public User queryById(Long id) {
        return userMapper.findById(id);
    }
}

@Service
@Transactional
public class UserService {
    
    @Autowired
    private UserMapper userMapper;
    
    @Transactional(readOnly = true)
    public User findById(Long id) {
        return userMapper.findById(id);
    }
    
    // 默認(rèn)具有事務(wù)支持
    public User save(User user) {
        User savedUser = userMapper.save(user);
        // 可能的其他業(yè)務(wù)邏輯
        return savedUser;
    }
    
    // 需要新事務(wù)的方法
    @Transactional(propagation = Propagation.REQUIRES_NEW)
    public void logUserAction(Long userId, String action) {
        // 記錄用戶操作日志
    }
}

@Service
@Scope("prototype") // 每次請(qǐng)求創(chuàng)建新實(shí)例
@Primary // 標(biāo)記為主要實(shí)現(xiàn)
public class DefaultUserService implements UserService {
    
    @Autowired
    private UserRepository userRepository;
    
    @Override
    @Cacheable("users") // 啟用緩存
    public User findById(Long id) {
        return userRepository.findById(id);
    }
    
    @Override
    @CacheEvict(value = "users", key = "#user.id") // 更新時(shí)清除緩存
    public User save(User user) {
        return userRepository.save(user);
    }
}

// 推薦的服務(wù)層設(shè)計(jì)
@Service
@Transactional(readOnly = true)
public class UserServiceImpl implements UserService {
    
    @Autowired
    private UserRepository userRepository;
    
    @Autowired
    private UserValidator userValidator;
    
    @Override
    public User findById(Long id) {
        return userRepository.findById(id)
                .orElseThrow(() -> new UserNotFoundException("User not found: " + id));
    }
    
    @Override
    @Transactional
    public User save(User user) {
        // 參數(shù)驗(yàn)證
        userValidator.validate(user);
        
        // 保存用戶
        User savedUser = userRepository.save(user);
        
        // 發(fā)布事件
        applicationEventPublisher.publishEvent(new UserSavedEvent(savedUser));
        
        return savedUser;
    }
    
    @Override
    @Transactional
    public void deleteById(Long id) {
        User user = findById(id);
        userRepository.delete(user);
        
        // 清理相關(guān)資源
        cleanupRelatedResources(user);
    }
    
    private void cleanupRelatedResources(User user) {
        // 清理用戶相關(guān)的資源
    }
}

@Service
public class UserService {
    
    @Autowired
    private UserMapper userMapper;
    
    public User queryById(Long id) {
        return userMapper.findById(id);
    }
}

@Service
public class UserService {
    
    private final UserMapper userMapper;
    
    // Spring 4.3+ 后，單構(gòu)造函數(shù)場(chǎng)景下可省略 @Autowired
    @Autowired
    public UserService(UserMapper userMapper) {
        this.userMapper = userMapper;
    }
    
    public User queryById(Long id) {
        return userMapper.findById(id);
    }
}

@Service
public class UserService {
    
    private UserMapper userMapper;
    
    @Autowired
    public void setUserMapper(UserMapper userMapper) {
        this.userMapper = userMapper;
    }
    
    public User queryById(Long id) {
        return userMapper.findById(id);
    }
}

@Service
public class PaymentService {
    
    // 注入所有 PaymentProcessor 的實(shí)現(xiàn)
    @Autowired
    private List<PaymentProcessor> paymentProcessors;
    
    // 注入所有 PaymentProcessor 實(shí)現(xiàn)及其名稱
    @Autowired
    private Map<String, PaymentProcessor> paymentProcessorMap;
    
    public void processPayment(String type, BigDecimal amount) {
        PaymentProcessor processor = paymentProcessorMap.get(type + "PaymentProcessor");
        if (processor != null) {
            processor.process(amount);
        }
    }
}

@Service
public class GenericService {
    
    // 注入 String 類型的 Repository
    @Autowired
    private GenericRepository<String> stringRepository;
    
    // 注入 Integer 類型的 Repository
    @Autowired
    private GenericRepository<Integer> integerRepository;
}

@Service
public class ConditionalService {
    
    // 可選注入，如果找不到 Bean 則為 null
    @Autowired(required = false)
    private OptionalFeature optionalFeature;
    
    public void performOperation() {
        // 使用可選功能
        if (optionalFeature != null) {
            optionalFeature.perform();
        }
        
        // 其他操作
    }
}

// 推薦的依賴注入方式
@Service
public class UserService {
    
    private final UserRepository userRepository;
    private final EmailService emailService;
    
    // 構(gòu)造函數(shù)注入（推薦）
    public UserService(UserRepository userRepository, 
                      @Autowired(required = false) EmailService emailService) {
        this.userRepository = userRepository;
        this.emailService = emailService;
    }
    
    public User createUser(User user) {
        User savedUser = userRepository.save(user);
        
        // 可選功能
        if (emailService != null) {
            emailService.sendWelcomeEmail(savedUser);
        }
        
        return savedUser;
    }
}

@Service
public class UserService {
    
    // 按字段名稱裝配，如果找不到則按類型裝配
    @Resource
    private UserMapper userMapper;
    
    public User queryById(Long id) {
        return userMapper.findById(id);
    }
}

@Service
public class UserService {
    
    // 明確按名稱裝配
    @Resource(name = "userDatabaseMapper")
    private UserMapper userMapper;
    
    // 裝配特定名稱的 DAO
    @Resource(name = "jdbcUserDao")
    private UserDao userDao;
}

@Service
public class UserService {
    
    // 按類型裝配，忽略字段名稱
    @Resource(type = UserMapper.class)
    private UserMapper userMapper;
}

@Service
public class PaymentService {
    
    // 使用 @Resource 按名稱裝配特定支付處理器
    @Resource(name = "alipayProcessor")
    private PaymentProcessor alipayProcessor;
    
    // 使用 @Autowired 按類型裝配所有支付處理器
    @Autowired
    private List<PaymentProcessor> allProcessors;
    
    public void processPayment(String type, BigDecimal amount) {
        switch (type) {
            case "alipay":
                alipayProcessor.process(amount);
                break;
            default:
                // 使用其他處理器
                break;
        }
    }
}

@Component
@Profile("production")
public class ProductionEmailService implements EmailService {
    // 生產(chǎn)環(huán)境實(shí)現(xiàn)
}

@Component
@Profile("development")
public class DevelopmentEmailService implements EmailService {
    // 開(kāi)發(fā)環(huán)境實(shí)現(xiàn)
}

@Service
public class NotificationService {
    
    // 在不同環(huán)境中自動(dòng)切換實(shí)現(xiàn)
    @Resource
    private EmailService emailService;
    
    public void sendNotification(String message) {
        emailService.send(message);
    }
}

// 推薦的 @Resource 使用方式
@Service
public class OrderService {
    
    // 明確按名稱裝配
    @Resource(name = "orderRepository")
    private OrderRepository orderRepository;
    
    // 按類型裝配（適用于單一實(shí)現(xiàn)）
    @Resource(type = PaymentService.class)
    private PaymentService paymentService;
    
    // 默認(rèn)裝配（適用于名稱匹配的場(chǎng)景）
    @Resource
    private InventoryService inventoryService;
    
    public void processOrder(Order order) {
        // 處理訂單邏輯
        orderRepository.save(order);
        paymentService.processPayment(order);
        inventoryService.updateInventory(order);
    }
}

@RestController
@RequestMapping("/api/users")
@CrossOrigin(origins = "http://localhost:3000")
public class UserController {
    
    @GetMapping
    public List<User> getUsers() {
        return userService.getAllUsers();
    }
    
    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.getUserById(id);
    }
}

@RestController
@RequestMapping("/api")
public class ApiController {
    
    // 允許來(lái)自特定域的請(qǐng)求
    @CrossOrigin(origins = "http://localhost:3000")
    @GetMapping("/user")
    public User getUser() {
        return new User("Bob", 25);
    }
    
    // 允許多個(gè)域的請(qǐng)求
    @CrossOrigin(origins = {"http://localhost:3000", "http://localhost:4000"})
    @GetMapping("/admin")
    public User getAdmin() {
        return new User("Admin", 30);
    }
}

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
    
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/api/**")
                .allowedOrigins("http://localhost:3000", "http://localhost:4000")
                .allowedMethods("GET", "POST", "PUT", "DELETE")
                .allowedHeaders("*")
                .exposedHeaders("X-Custom-Header")
                .allowCredentials(true)
                .maxAge(3600);
    }
}

@RestController
@RequestMapping("/api")
public class ComplexController {
    
    // 允許所有域，但限制方法和頭
    @CrossOrigin(
        origins = "*",
        methods = {RequestMethod.GET, RequestMethod.POST},
        allowedHeaders = {"Content-Type", "Authorization"},
        exposedHeaders = {"X-Total-Count"},
        maxAge = 3600
    )
    @GetMapping("/data")
    public List<Data> getData() {
        return dataService.getAll();
    }
    
    // 需要攜帶憑證的跨域請(qǐng)求
    @CrossOrigin(
        origins = "http://trusted-domain.com",
        allowCredentials = "true"
    )
    @PostMapping("/secure")
    public ResponseEntity<String> secureOperation() {
        return ResponseEntity.ok("Secure operation completed");
    }
}

// 推薦的生產(chǎn)環(huán)境 CORS 配置
@RestController
@RequestMapping("/api/users")
@CrossOrigin(
    origins = {"https://myapp.example.com", "https://admin.example.com"},
    methods = {RequestMethod.GET, RequestMethod.POST, RequestMethod.PUT, RequestMethod.DELETE},
    allowedHeaders = {"Content-Type", "Authorization", "X-Requested-With"},
    exposedHeaders = {"X-Total-Count"},
    maxAge = 3600
)
public class UserController {
    
    @Autowired
    private UserService userService;
    
    @GetMapping
    public ResponseEntity<List<User>> getUsers() {
        List<User> users = userService.findAll();
        return ResponseEntity.ok(users);
    }
    
    @PostMapping
    public ResponseEntity<User> createUser(@RequestBody User user) {
        User savedUser = userService.save(user);
        return ResponseEntity.status(HttpStatus.CREATED).body(savedUser);
    }
}

@Configuration
public class AppConfig {
    
    @Bean
    public UserService userService() {
        return new UserServiceImpl();
    }
    
    @Bean
    public UserMapper userMapper() {
        return new UserMapperImpl();
    }
}

@Configuration
public class DatabaseConfig {
    
    @Value("${database.url}")
    private String databaseUrl;
    
    @Value("${database.username}")
    private String username;
    
    @Value("${database.password}")
    private String password;
    
    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setUrl(databaseUrl);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        return dataSource;
    }
    
    @Bean
    public JdbcTemplate jdbcTemplate(DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }
}

@Configuration
@Profile("production")
public class ProductionDatabaseConfig {
    
    @Bean
    public DataSource dataSource() {
        // 生產(chǎn)環(huán)境數(shù)據(jù)源配置
        return new HikariDataSource();
    }
}

@Configuration
@Profile("development")
public class DevelopmentDatabaseConfig {
    
    @Bean
    public DataSource dataSource() {
        // 開(kāi)發(fā)環(huán)境數(shù)據(jù)源配置
        return new DriverManagerDataSource();
    }
}

@Configuration
@ComponentScan("com.example")
@Import({DatabaseConfig.class, SecurityConfig.class})
@PropertySource("classpath:application.properties")
public class MainConfig {
    
    @Bean
    public ApplicationService applicationService() {
        return new ApplicationServiceImpl();
    }
}

// 推薦的配置類設(shè)計(jì)
@Configuration
@PropertySource("classpath:app.properties")
@ComponentScan(basePackages = "com.example")
@Import({DatabaseConfig.class, SecurityConfig.class})
public class ApplicationConfig {
    
    @Value("${app.name:MyApplication}")
    private String applicationName;
    
    @Bean
    public ApplicationService applicationService(
            UserService userService, 
            NotificationService notificationService) {
        ApplicationServiceImpl service = new ApplicationServiceImpl();
        service.setUserService(userService);
        service.setNotificationService(notificationService);
        service.setApplicationName(applicationName);
        return service;
    }
}

@Configuration
public class AppConfig {
    
    @Bean
    public UserService userService() {
        return new UserServiceImpl();
    }
    
    @Bean
    public UserMapper userMapper() {
        return new UserMapperImpl();
    }
}

@Configuration
public class AppConfig {
    
    @Bean
    public UserMapper userMapper() {
        return new UserMapperImpl();
    }
    
    // 方法參數(shù)會(huì)自動(dòng)從容器中獲取并注入
    @Bean
    public UserService userService(UserMapper userMapper) {
        UserServiceImpl service = new UserServiceImpl();
        service.setUserMapper(userMapper);
        return service;
    }
}

@Configuration
public class AppConfig {
    
    @Bean(name = "customUserService", initMethod = "initialize", destroyMethod = "cleanup")
    public UserService userService() {
        UserServiceImpl userService = new UserServiceImpl();
        userService.setSomeProperty("value");
        return userService;
    }
    
    @Bean("namedMapper")
    public UserMapper userMapper() {
        return new UserMapperImpl();
    }
}

@Configuration
public class AppConfig {
    
    @Bean
    @Scope("singleton") // 默認(rèn)作用域
    public UserService singletonUserService() {
        return new UserServiceImpl();
    }
    
    @Bean
    @Scope("prototype")
    public UserMapper prototypeUserMapper() {
        return new UserMapperImpl();
    }
    
    @Bean
    @Scope(value = "session", proxyMode = ScopedProxyMode.TARGET_CLASS)
    public ShoppingCart sessionCart() {
        return new ShoppingCart();
    }
}

// 推薦的 @Bean 使用方式
@Configuration
public class DatabaseConfig {
    
    @Value("${database.pool.size:10}")
    private int poolSize;
    
    @Bean(name = "primaryDataSource", initMethod = "init", destroyMethod = "close")
    public DataSource primaryDataSource() {
        HikariDataSource dataSource = new HikariDataSource();
        dataSource.setMaximumPoolSize(poolSize);
        // 其他配置...
        return dataSource;
    }
    
    @Bean
    @Scope("prototype")
    public JdbcTemplate jdbcTemplate(DataSource primaryDataSource) {
        return new JdbcTemplate(primaryDataSource);
    }
    
    @Bean
    public TransactionTemplate transactionTemplate(PlatformTransactionManager txManager) {
        return new TransactionTemplate(txManager);
    }
}

@Component
public class MyComponent {
    
    public void doSomething() {
        System.out.println("執(zhí)行某些操作");
    }
}

@Component("myCustomComponent")
public class MyComponent {
    
    public void performAction() {
        System.out.println("執(zhí)行操作");
    }
}

@Component
@Profile("development")
public class DevelopmentService {
    
    public void performAction() {
        System.out.println("開(kāi)發(fā)環(huán)境下的操作");
    }
}

@Component
@Profile("production")
public class ProductionService {
    
    public void performAction() {
        System.out.println("生產(chǎn)環(huán)境下的操作");
    }
}

@Component
@Scope("prototype")
public class PrototypeComponent {
    
    public void doSomething() {
        System.out.println("原型組件操作");
    }
}

@Component
@Scope(value = "session", proxyMode = ScopedProxyMode.TARGET_CLASS)
public class SessionScopedComponent {
    
    public void doSessionWork() {
        System.out.println("會(huì)話范圍組件操作");
    }
}

// 推薦的組件設(shè)計(jì)
@Component
public class FileStorageService {
    
    private final StorageProperties storageProperties;
    
    // 構(gòu)造函數(shù)注入（推薦）
    public FileStorageService(StorageProperties storageProperties) {
        this.storageProperties = storageProperties;
    }
    
    public void saveFile(MultipartFile file) {
        // 文件保存邏輯
        String location = storageProperties.getLocation();
        // 實(shí)際保存操作
    }
    
    public byte[] loadFile(String filename) {
        // 文件加載邏輯
        return new byte[0];
    }
}

@Component
public class DatabaseConfig {
    
    @Value("${database.url}")
    private String databaseUrl;
    
    @Value("${database.username}")
    private String username;
    
    @Value("${database.password}")
    private String password;
    
    // 使用注入的屬性
    public DataSource createDataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setUrl(databaseUrl);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        return dataSource;
    }
}

@Component
public class AppConfig {
    
    // 如果配置文件中沒(méi)有定義 server.port，則使用默認(rèn)值 8080
    @Value("${server.port:8080}")
    private int serverPort;
    
    // 字符串默認(rèn)值
    @Value("${app.name:MyApplication}")
    private String appName;
    
    // 數(shù)組默認(rèn)值
    @Value("${app.servers:server1,server2,server3}")
    private String[] servers;
}

@Component
public class ExpressionConfig {
    
    // 字面量表達(dá)式
    @Value("#{10 * 20}")
    private int calculationResult;
    
    // 系統(tǒng)屬性
    @Value("#{systemProperties['java.home']}")
    private String javaHome;
    
    // 隨機(jī)值
    @Value("#{T(java.lang.Math).random() * 100.0}")
    private double randomNumber;
    
    // 調(diào)用其他 Bean 的方法
    @Value("#{databaseConfig.databaseUrl}")
    private String dbUrlFromBean;
    
    // 三元操作符
    @Value("#{systemProperties['app.dev'] == 'true' ? 'dev' : 'prod'}")
    private String environment;
}

@Component
public class CollectionConfig {
    
    // 注入列表（逗號(hào)分隔）
    @Value("${app.roles:admin,user,guest}")
    private List<String> roles;
    
    // 注入集合
    @Value("${app.permissions:read,write,execute}")
    private Set<String> permissions;
    
    // 注入映射（需要特殊格式）
    @Value("#{${app.settings}}")
    private Map<String, String> settings;
}

@Component
public class ConditionalConfig {
    
    // 根據(jù)系統(tǒng)屬性決定是否啟用某個(gè)功能
    @Value("#{systemProperties['feature.enabled'] ?: false}")
    private boolean featureEnabled;
    
    // 根據(jù)配置文件決定超時(shí)時(shí)間
    @Value("#{${app.timeout:30} * 1000}")
    private long timeoutInMillis;
}

// 推薦的配置管理方式
@Component
@PropertySource("classpath:app.properties")
public class ApplicationConfig {
    
    @Value("${app.name:DefaultApp}")
    private String appName;
    
    @Value("${app.version:1.0.0}")
    private String appVersion;
    
    @Value("${app.debug:false}")
    private boolean debugMode;
    
    @Value("${app.max-connections:100}")
    private int maxConnections;
    
    // 對(duì)于復(fù)雜配置，建議使用 @ConfigurationProperties
    @Value("${app.whitelist:127.0.0.1,localhost}")
    private List<String> whitelist;
    
    // 提供 getter 方法供其他組件使用
    public String getAppName() {
        return appName;
    }
    
    public String getAppVersion() {
        return appVersion;
    }
    
    public boolean isDebugMode() {
        return debugMode;
    }
    
    public int getMaxConnections() {
        return maxConnections;
    }
    
    public List<String> getWhitelist() {
        return whitelist;
    }
}

@Configuration
@PropertySource("classpath:database.properties")
public class DatabaseConfiguration {
    
    @Value("${database.driver:com.mysql.cj.jdbc.Driver}")
    private String driverClassName;
    
    @Value("${database.url}")
    private String url;
    
    @Value("${database.username}")
    private String username;
    
    @Value("${database.password}")
    private String password;
    
    @Bean
    public DataSource dataSource() {
        HikariDataSource dataSource = new HikariDataSource();
        dataSource.setDriverClassName(driverClassName);
        dataSource.setJdbcUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        return dataSource;
    }
}

@Component
public class EmailService {

    private final String smtpHost;
    private final int smtpPort;
    private final boolean useSSL;

    // 構(gòu)造函數(shù)注入配置值
    public EmailService(
            @Value("${mail.smtp.host:localhost}") String smtpHost,
            @Value("${mail.smtp.port:25}") int smtpPort,
            @Value("${mail.smtp.ssl:false}") boolean useSSL) {
        this.smtpHost = smtpHost;
        this.smtpPort = smtpPort;
        this.useSSL = useSSL;
    }

    // 郵件發(fā)送邏輯
    public void sendEmail(String to, String subject, String content) {
        // 實(shí)現(xiàn)郵件發(fā)送邏輯
    }
}