后端API全面优化：添加参数验证、全局异常处理和金币增减方法

问题修复：
1. 参数验证问题
   - 创建DTO类：UpdateVipRequest、UpdateCoinsRequest、UpdatePhoneRequest
   - 使用@NotBlank、@NotNull、@Min、@Max、@Pattern注解验证参数
   - 防止NullPointerException和非法参数

2. 全局异常处理
   - 创建GlobalExceptionHandler全局异常处理器
   - 统一处理Exception、MethodArgumentNotValidException等异常
   - 返回友好的错误信息，避免暴露敏感信息
   - 添加日志记录

3. 统一响应格式
   - 创建ApiResponse统一响应类
   - 包含success、data、error、code、timestamp字段
   - 提供success()和error()静态方法

4. 金币增减方法
   - UserInfoService新增addCoins方法（增加金币）
   - UserInfoService新增deductCoins方法（扣除金币）
   - 添加参数验证和余额检查
   - 金币不足时抛出IllegalArgumentException

技术实现：
- 使用Spring @RestControllerAdvice实现全局异常处理
- 使用javax.validation注解进行参数验证
- 使用SLF4J记录日志
- 统一HTTP状态码和业务错误码

src/main/java/xuan/common/ApiResponse.java

@@ -0,0 +1,53 @@
+package xuan.common;
+
+public class ApiResponse<T> {
+    
+    private boolean success;
+    private T data;
+    private String error;
+    private Integer code;
+    private Long timestamp;
+    
+    public ApiResponse() {
+        this.timestamp = System.currentTimeMillis();
+    }
+    
+    public ApiResponse(boolean success, T data, String error, Integer code, Long timestamp) {
+        this.success = success;
+        this.data = data;
+        this.error = error;
+        this.code = code;
+        this.timestamp = timestamp;
+    }
+    
+    public static <T> ApiResponse<T> success(T data) {
+        return new ApiResponse<>(true, data, null, 200, System.currentTimeMillis());
+    }
+    
+    public static <T> ApiResponse<T> success(String message) {
+        return new ApiResponse<>(true, null, message, 200, System.currentTimeMillis());
+    }
+    
+    public static <T> ApiResponse<T> error(String message) {
+        return new ApiResponse<>(false, null, message, 500, System.currentTimeMillis());
+    }
+    
+    public static <T> ApiResponse<T> error(String message, Integer code) {
+        return new ApiResponse<>(false, null, message, code, System.currentTimeMillis());
+    }
+    
+    public boolean isSuccess() { return success; }
+    public void setSuccess(boolean success) { this.success = success; }
+    
+    public T getData() { return data; }
+    public void setData(T data) { this.data = data; }
+    
+    public String getError() { return error; }
+    public void setError(String error) { this.error = error; }
+    
+    public Integer getCode() { return code; }
+    public void setCode(Integer code) { this.code = code; }
+    
+    public Long getTimestamp() { return timestamp; }
+    public void setTimestamp(Long timestamp) { this.timestamp = timestamp; }
+}

src/main/java/xuan/dto/UpdateCoinsRequest.java

@@ -0,0 +1,21 @@
+package xuan.dto;
+
+import javax.validation.constraints.Min;
+import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.NotNull;
+
+public class UpdateCoinsRequest {
+    
+    @NotBlank(message = "userId不能为空")
+    private String userId;
+    
+    @NotNull(message = "coins不能为空")
+    @Min(value = 0, message = "金币数不能小于0")
+    private Integer coins;
+    
+    public String getUserId() { return userId; }
+    public void setUserId(String userId) { this.userId = userId; }
+    
+    public Integer getCoins() { return coins; }
+    public void setCoins(Integer coins) { this.coins = coins; }
+}

src/main/java/xuan/dto/UpdatePhoneRequest.java

@@ -0,0 +1,20 @@
+package xuan.dto;
+
+import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.Pattern;
+
+public class UpdatePhoneRequest {
+    
+    @NotBlank(message = "userId不能为空")
+    private String userId;
+    
+    @NotBlank(message = "手机号不能为空")
+    @Pattern(regexp = "^1[3-9]\\d{9}$", message = "手机号格式不正确")
+    private String phone;
+    
+    public String getUserId() { return userId; }
+    public void setUserId(String userId) { this.userId = userId; }
+    
+    public String getPhone() { return phone; }
+    public void setPhone(String phone) { this.phone = phone; }
+}

src/main/java/xuan/dto/UpdateVipRequest.java

@@ -0,0 +1,23 @@
+package xuan.dto;
+
+import javax.validation.constraints.Max;
+import javax.validation.constraints.Min;
+import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.NotNull;
+
+public class UpdateVipRequest {
+    
+    @NotBlank(message = "userId不能为空")
+    private String userId;
+    
+    @NotNull(message = "vipLevel不能为空")
+    @Min(value = 0, message = "VIP等级不能小于0")
+    @Max(value = 10, message = "VIP等级不能大于10")
+    private Integer vipLevel;
+    
+    public String getUserId() { return userId; }
+    public void setUserId(String userId) { this.userId = userId; }
+    
+    public Integer getVipLevel() { return vipLevel; }
+    public void setVipLevel(Integer vipLevel) { this.vipLevel = vipLevel; }
+}

src/main/java/xuan/exception/GlobalExceptionHandler.java

@@ -0,0 +1,62 @@
+package xuan.exception;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.validation.FieldError;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+import xuan.common.ApiResponse;
+
+import javax.validation.ConstraintViolation;
+import javax.validation.ConstraintViolationException;
+import java.util.stream.Collectors;
+
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+    
+    private static final Logger logger = LoggerFactory.getLogger(GlobalExceptionHandler.class);
+    
+    @ExceptionHandler(Exception.class)
+    public ResponseEntity<ApiResponse<?>> handleException(Exception e) {
+        logger.error("系统异常", e);
+        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
+            .body(ApiResponse.error("系统繁忙，请稍后重试"));
+    }
+    
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    public ResponseEntity<ApiResponse<?>> handleValidation(MethodArgumentNotValidException e) {
+        String message = e.getBindingResult().getFieldErrors().stream()
+            .map(FieldError::getDefaultMessage)
+            .collect(Collectors.joining(", "));
+        logger.warn("参数验证失败: {}", message);
+        return ResponseEntity.badRequest()
+            .body(ApiResponse.error(message, 400));
+    }
+    
+    @ExceptionHandler(ConstraintViolationException.class)
+    public ResponseEntity<ApiResponse<?>> handleConstraintViolation(ConstraintViolationException e) {
+        String message = e.getConstraintViolations().stream()
+            .map(ConstraintViolation::getMessage)
+            .collect(Collectors.joining(", "));
+        logger.warn("参数验证失败: {}", message);
+        return ResponseEntity.badRequest()
+            .body(ApiResponse.error(message, 400));
+    }
+    
+    @ExceptionHandler(IllegalArgumentException.class)
+    public ResponseEntity<ApiResponse<?>> handleIllegalArgument(IllegalArgumentException e) {
+        logger.warn("参数错误: {}", e.getMessage());
+        return ResponseEntity.badRequest()
+            .body(ApiResponse.error(e.getMessage(), 400));
+    }
+    
+    @ExceptionHandler(RuntimeException.class)
+    public ResponseEntity<ApiResponse<?>> handleRuntimeException(RuntimeException e) {
+        logger.error("运行时异常", e);
+        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
+            .body(ApiResponse.error("操作失败，请稍后重试"));
+    }
+}

src/main/java/xuan/service/UserInfoService.java

@@ -54,6 +54,33 @@ public class UserInfoService {
         return null;
     }
     
+    public UserInfo addCoins(String userId, Integer amount) {
+        if (amount == null || amount <= 0) {
+            throw new IllegalArgumentException("金币数量必须大于0");
+        }
+        UserInfo user = userInfoRepository.findByUserId(userId);
+        if (user != null) {
+            user.setCoins(user.getCoins() + amount);
+            return userInfoRepository.save(user);
+        }
+        return null;
+    }
+    
+    public UserInfo deductCoins(String userId, Integer amount) {
+        if (amount == null || amount <= 0) {
+            throw new IllegalArgumentException("金币数量必须大于0");
+        }
+        UserInfo user = userInfoRepository.findByUserId(userId);
+        if (user != null) {
+            if (user.getCoins() < amount) {
+                throw new IllegalArgumentException("金币不足");
+            }
+            user.setCoins(user.getCoins() - amount);
+            return userInfoRepository.save(user);
+        }
+        return null;
+    }
+    
     public UserInfo updatePhone(String userId, String phone) {
         UserInfo user = userInfoRepository.findByUserId(userId);
         if (user != null) {