利用 redis 实现登陆次数限制, 注解 + aop, 核心代码很简单.
# 基本思路
比如希望达到的要求是这样: 在 1min 内登陆异常次数达到5次, 锁定该用户 1h
那么登陆请求的参数中, 会有一个参数唯一标识一个 user, 比如 邮箱/手机号/userName
用这个参数作为key存入redis, 对应的value为登陆错误的次数, string 类型, 并设置过期时间为 1min. 当获取到的 value == "4" , 说明当前请求为第 5 次登陆异常, 锁定.
所谓的锁定, 就是将对应的value设置为某个标识符, 比如"lock", 并设置过期时间为 1h
# 核心代码
定义一个注解, 用来标识需要登陆次数校验的方法
```java
package io.github.xiaoyureed.redispractice.anno;
import java.lang.annotation.*;
@Documented
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface RedisLimit {
/**
* 标识参数名, 必须是请求参数中的一个
*/
String identifier();
/**
* 在多长时间内监控, 如希望在 60s 内尝试
* 次数限制为5次, 那么 watch=60; unit: s
*/
long watch();
/**
* 锁定时长, unit: s
*/
long lock();
/**
* 错误的尝试次数
*/
int times();
}
```
编写切面, 在目标方法前后进行校验, 处理...
```java
package io.github.xiaoyureed.redispractice.aop;
@Component
@Aspect
// Ensure that current advice is outer compared with ControllerAOP
// so we can handling login limitation Exception in this aop advice.
//@Order(9)
@Slf4j
public class RedisLimitAOP {
@Autowired
private StringRedisTemplate stringRedisTemplate;
@Around("@annotation(io.github.xiaoyureed.redispractice.anno.RedisLimit)")
public Object handleLimit(ProceedingJoinPoint joinPoint) {
MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature();
final Method method = methodSignature.getMethod();
final RedisLimit redisLimitAnno = method.getAnnotation(RedisLimit.class);// 貌似可以直接在方法参数中注入 todo
final String identifier = redisLimitAnno.identifier();
final long watch = redisLimitAnno.watch();
final int times = redisLimitAnno.times();
final long lock = redisLimitAnno.lock();
// final ServletRequestAttributes att = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();
// final HttpServletRequest request = att.getRequest();
// final String identifierValue = request.getParameter(identifier);
String identifierValue = null;
try {
final Object arg = joinPoint.getArgs()[0];
final Field declaredField = arg.getClass().getDeclaredField(identifier);
declaredField.setAccessible(true);
identifierValue = (String) declaredField.get(arg);
} catch (NoSuchFieldException e) {
log.error(">>> invalid identifier [{}], cannot find this field in request params", identifier);
} catch (IllegalAccessException e) {
e.printStackTrace();
}
if (StringUtils.isBlank(identifierValue)) {
log.error(">>> the value of RedisLimit.identifier cannot be blank, invalid identifier: {}", identifier);
}
// check User locked
final ValueOperations<String, String> ssOps = stringRedisTemplate.opsForValue();
final String flag = ssOps.get(identifierValue);
if (flag != null && "lock".contentEquals(flag)) {
final BaseResp result = new BaseResp();
result.setErrMsg("user locked");
result.setCode("1");
return new ResponseEntity<>(result, HttpStatus.OK);
}
ResponseEntity result;
try {
result = (ResponseEntity) joinPoint.proceed();
} catch (Throwable e) {
result = handleLoginException(e, identifierValue, watch, times, lock);
}
return result;
}
private ResponseEntity handleLoginException(Throwable e, String identifierValue, long watch, int times, long lock) {
final BaseResp result = new BaseResp();
result.setCode("1");
if (e instanceof LoginException) {
log.info(">>> handle login exception...");
final ValueOperations<String, String> ssOps = stringRedisTemplate.opsForValue();
Boolean exist = stringRedisTemplate.hasKey(identifierValue);
// key doesn't exist, so it is the first login failure
if (exist == null || !exist) {
ssOps.set(identifierValue, "1", watch, TimeUnit.SECONDS);
result.setErrMsg(e.getMessage());
return new ResponseEntity<>(result, HttpStatus.OK);
}
String count = ssOps.get(identifierValue);
// has been reached the limitation
if (Integer.parseInt(count) + 1 == times) {
log.info(">>> [{}] has been reached the limitation and will be locked for {}s", identifierValue, lock);
ssOps.set(identifierValue, "lock", lock, TimeUnit.SECONDS);
result.setErrMsg("user locked");
return new ResponseEntity<>(result, HttpStatus.OK);
}
ssOps.increment(identifierValue);
result.setErrMsg(e.getMessage() + "; you have try " + ssOps.get(identifierValue) + "times.");
}
log.error(">>> RedisLimitAOP cannot handle {}", e.getClass().getName());
return new ResponseEntity<>(result, HttpStatus.OK);
}
}
```
这样使用:
```java
package io.github.xiaoyureed.redispractice.web;
@RestController
public class SessionResources {
@Autowired
private SessionService sessionService;
/**
* 1 min 之内尝试超过5次, 锁定 user 1h
*/
@RedisLimit(identifier = "name", watch = 30, times = 5, lock = 10)
@RequestMapping(value = "/session", method = RequestMethod.POST)
public ResponseEntity<LoginResp> login(@Validated @RequestBody LoginReq req) {
return new ResponseEntity<>(sessionService.login(req), HttpStatus.OK);
}
}
```
# references
https://github.com/xiaoyureed/redis-login-limitation
