SpringBoot项目参数校验过程

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
    <version>2.7.18</version>
</dependency>

@Data
public class UserDTO {
    @NotBlank(message = "用户名不能为空")
    @Size(min = 2, max = 20, message = "用户名长度必须在2-20个字符之间")
    private String username;
    
    @NotNull(message = "年龄不能为空")
    @Min(value = 18, message = "年龄不能小于18岁")
    @Max(value = 60, message = "年龄不能大于60岁")
    private Integer age;
    
    @Email(message = "邮箱格式不正确")
    private String email;
    
    @Pattern(regexp = "^1[3-9]\\d{9}$", message = "手机号格式不正确")
    private String phone;
    
}

@Data
public class UserDTO {
    @NotBlank(message = "用户名不能为空")
    @Size(min = 2, max = 20, message = "用户名长度必须在2-20个字符之间")
    private String username;
    
    @NotNull(message = "年龄不能为空")
    @Min(value = 18, message = "年龄不能小于18岁")
    @Max(value = 60, message = "年龄不能大于60岁")
    private Integer age;
    
    @Email(message = "邮箱格式不正确")
    private String email;
    
    @Pattern(regexp = "^1[3-9]\\d{9}$", message = "手机号格式不正确")
    private String phone;
    
}

@Validated
@RestController
@RequestMapping("/users")
public class UserController {
    
    @PostMapping
    public ResponseEntity<User> createUser(@RequestBody @Valid UserDTO userDTO) {
        // 业务逻辑处理（只有校验通过才会执行到这里）
        return ResponseEntity.ok(userService.create(userDTO));
    }
    
    // 单个参数校验需要在类上添加@Validated
    @GetMapping("/detail")
    public ResponseEntity<User> getUserDetail(@NotBlank String username) {
        // 业务逻辑处理
        return ResponseEntity.ok(userService.findByUsername(username));
    }
}

@RestControllerAdvice
public class GlobalExceptionHandler {
    
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<ErrorResponse> handleValidationException(
            MethodArgumentNotValidException ex) {
        
        List<String> errors = ex.getBindingResult()
                .getFieldErrors()
                .stream()
                .map(error -> error.getField() + ": " + error.getDefaultMessage())
                .collect(Collectors.toList());
        
        return ResponseEntity.badRequest()
                .body(new ErrorResponse("VALIDATION_FAILED", errors));
    }
    
    @ExceptionHandler(ConstraintViolationException.class)
    public ResponseEntity<ErrorResponse> handleConstraintViolationException(
            ConstraintViolationException ex) {
        
        List<String> errors = ex.getConstraintViolations()
                .stream()
                .map(violation -> violation.getPropertyPath() + ": " + violation.getMessage())
                .collect(Collectors.toList());
        
        return ResponseEntity.badRequest()
                .body(new ErrorResponse("PARAMETER_VALIDATION_FAILED", errors));
    }
}

@Data
public class ErrorResponse {
    private String msg;
    private Object errors;
    public ErrorResponse(String msg, Object data) {
        this.msg = msg;
        this.errors = data;
    }
}