Spring Boot 自定义注解实战：5 个高频案例详解

常见实战案例

1. 自定义日志注解

效果：调用接口时自动打印耗时和参数。

定义注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MethodLog {
    String value() default "";
    boolean printArgs() default true;
    boolean printResult() default true;
    boolean timing() default true;
}

切面实现

这里以打印输出为例，生产环境可结合数据库或日志系统入库。

@Aspect
@Component
@Slf4j
public class MethodLogAspect {
    @Around("@annotation(methodLog)")
    public Object around(ProceedingJoinPoint joinPoint, MethodLog methodLog) throws Throwable {
        String methodName = joinPoint.getSignature().getName();
        String className = joinPoint.getTarget().getClass().getSimpleName();
        long startTime = System.currentTimeMillis();

        if (methodLog.printArgs()) {
            log.info("[{}#{}] 方法调用，参数：{}", className, methodName, Arrays.toString(joinPoint.getArgs()));
        }

        try {
            Object result = joinPoint.proceed();
            if (methodLog.printResult()) {
                log.info("[{}#{}] 方法返回：{}", className, methodName, result);
            }
            if (methodLog.timing()) {
                log.info("[{}#{}] 方法执行耗时：{}ms", className, methodName, System.currentTimeMillis() - startTime);
            }
            return result;
        } catch (Exception e) {
            log.error("[{}#{}] 方法执行异常：{}", className, methodName, e.getMessage());
            throw e;
        }
    }
}

使用示例

@RestController
@RequestMapping("/api/user")
public class UserController {
    @PostMapping
    @MethodLog(value = "创建用户", printArgs = true, printResult = true, timing = true)
    public User createUser(@RequestBody User user) {
        return userService.save(user);
    }
}

2. 自定义参数校验注解

默认 validation 足够应付大部分场景，但特殊规则需自定义。

定义注解

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.*;

@Target({ElementType.FIELD, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = PhoneValidator.class)
public @interface Phone {
    String message() default "手机号格式错误";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

实现校验器

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

public class PhoneValidator implements ConstraintValidator<Phone, String> {
    @Override
    public boolean isValid(String value, ConstraintValidatorContext context) {
        return value != null && value.matches("^1[3-9]\\d{9}$");
    }
}

使用示例

@RestController
public class RegisterController {
    @PostMapping("/register")
    public String register(@Valid @RequestBody UserDTO userDTO) {
        return "注册成功";
    }

    public static class UserDTO {
        private String name;
        @Phone
        private String phone;
        // getter/setter
    }
}

3. 自定义权限校验注解

模拟 @PreAuthorize 功能。

定义注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface CheckPermission {
    String value();
}

实现 AOP 权限校验

@Aspect
@Component
public class PermissionAspect {
    @Before("@annotation(checkPermission)")
    public void check(JoinPoint joinPoint, CheckPermission checkPermission) {
        String requiredPermission = checkPermission.value();
        // 模拟从上下文获取当前用户权限
        String userPermission = "USER"; 
        if (!userPermission.equals(requiredPermission)) {
            throw new RuntimeException("权限不足，缺少：" + requiredPermission);
        }
    }
}

使用示例

@RestController
public class AdminController {
    @CheckPermission("ADMIN")
    @GetMapping("/admin")
    public String adminPage() {
        return "管理员页面";
    }
}

4. 自定义分布式限流注解

定义注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface RateLimit {
    String key() default "";
    int limit() default 100;
    int timeWindow() default 60;
    String message() default "访问过于频繁，请稍后再试";
}

切面实现

这里使用简单的令牌桶算法实现。

@Aspect
@Component
@Slf4j
public class RateLimitAspect {
    private final Map<String, RateLimiter> limiterMap = new ConcurrentHashMap<>();

    @Before("@annotation(rateLimit)")
    public void rateLimitCheck(RateLimit rateLimit) {
        String key = generateKey(rateLimit);
        RateLimiter limiter = limiterMap.computeIfAbsent(key, k -> RateLimiter.create(rateLimit.limit() / (double) rateLimit.timeWindow()));
        if (!limiter.tryAcquire()) {
            throw new RuntimeException(rateLimit.message());
        }
    }

    private String generateKey(RateLimit rateLimit) {
        String key = rateLimit.key();
        if (StringUtils.isEmpty(key)) {
            return "rate_limit:" + System.identityHashCode(rateLimit);
        }
        return "rate_limit:" + key;
    }
}

class RateLimiter {
    private final double capacity;
    private final double refillTokensPerOneMillis;
    private double availableTokens;
    private long lastRefillTimestamp;

    public static RateLimiter create(double permitsPerSecond) {
        return new RateLimiter(permitsPerSecond);
    }

    private RateLimiter(double permitsPerSecond) {
        this.capacity = permitsPerSecond;
        this.refillTokensPerOneMillis = permitsPerSecond / 1000.0;
        this.availableTokens = permitsPerSecond;
        this.lastRefillTimestamp = System.currentTimeMillis();
    }

    public synchronized boolean tryAcquire() {
        refill();
        if (availableTokens < 1) {
            return false;
        }
        availableTokens -= 1;
        return true;
    }

    private void refill() {
        long currentTime = System.currentTimeMillis();
        if (currentTime > lastRefillTimestamp) {
            long millisSinceLastRefill = currentTime - lastRefillTimestamp;
            double refill = millisSinceLastRefill * refillTokensPerOneMillis;
            this.availableTokens = Math.min(capacity, availableTokens + refill);
            this.lastRefillTimestamp = currentTime;
        }
    }
}

使用示例

@RestController
@RequestMapping("/api")
public class ApiController {
    @GetMapping("/public/data")
    @RateLimit(limit = 10, timeWindow = 60, message = "接口调用频率超限")
    public ApiResponse getPublicData() {
        return ApiResponse.success("公开数据");
    }
}

5. 自定义加解密注解

可参考 Spring Boot 整合 Jasypt 库实现敏感字段加解密，此处不再赘述源码，核心思路一致：定义注解标记字段，通过 AOP 拦截 Setter 方法进行加密处理。

总结

通过上述 5 个案例，展示了 Spring Boot 自定义注解在日志、校验、权限、限流及加解密场景的应用。合理使用自定义注解，能大幅提升代码的可读性、可维护性和复用性。实际项目中，可根据需求灵活组合扩展，构建更健壮的应用程序。