服务器上的Redis已经安装完成了（安装步骤见上篇文章），今天就让我们使用Redis来做个小功能：自定义拦截器限制访问次数，也就是限流。
首先我们要在项目中引入Redis
1、引入依赖
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> </dependency> <!-- redis依赖commons-pool 这个依赖一定要添加 --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-pool2</artifactId> </dependency>
2、application.yml配置
server: port: 8181 spring: redis: host: 127.0.0.1 port: 6379 timeout: 10s lettuce: pool: # 连接池中的最小空闲连接 默认0 min-idle: 0 # 连接池中的最大空闲连接 默认8 max-idle: 8 # 连接池最大连接数 默认8 ，负数表示没有限制 max-active: 8 # 连接池最大阻塞等待时间（使用负值表示没有限制） 默认-1 max-wait: -1ms #选择哪个库存储，默认是0 database: 0 password: 123456
3、创建redisConfig，引入redisTemplate
@Configuration public class RedisConfig { @Bean public RedisTemplate<String, Object> redisTemplate(LettuceConnectionFactory redisConnectionFactory) { RedisTemplate<String, Object> redisTemplate = new RedisTemplate<String, Object>(); redisTemplate.setKeySerializer(new StringRedisSerializer()); redisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer()); redisTemplate.setHashKeySerializer(new StringRedisSerializer()); redisTemplate.setHashValueSerializer(new GenericJackson2JsonRedisSerializer()); redisTemplate.setConnectionFactory(redisConnectionFactory); return redisTemplate; } }
然后我们书写自定义注解和拦截器
1、自定义注解
@Retention(RetentionPolicy.RUNTIME) @Target(ElementType.METHOD) @Documented public @interface AccessLimit { int seconds(); //秒数 int maxCount(); //最大访问次数 boolean needLogin()default true;//是否需要登录 }
2、创建拦截器
@Component public class FangshuaInterceptor extends HandlerInterceptorAdapter { @Autowired private RedisTemplate redisTemplate; @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { //判断请求是否属于方法的请求 if(handler instanceof HandlerMethod){ HandlerMethod hm = (HandlerMethod) handler; //获取方法中的注解,看是否有该注解 AccessLimit accessLimit = hm.getMethodAnnotation(AccessLimit.class); if(accessLimit == null){ return true; } int seconds = accessLimit.seconds(); int maxCount = accessLimit.maxCount(); boolean login = accessLimit.needLogin(); String key = request.getRequestURI(); //如果需要登录 if(login){ //获取登录的session进行判断，此处只是例子，不写具体的业务 //..... key+=""+"1"; //这里假设用户是1,项目中是动态获取的userId } //从redis中获取用户访问的次数 Integer count; if(Objects.isNull(redisTemplate.opsForValue().get(key))){ count = 0; }else{ count = (Integer) redisTemplate.opsForValue().get(key); } if(count == 0){ redisTemplate.opsForValue().set(key,1,seconds, TimeUnit.SECONDS); }else if(count<maxCount){ //key的值加1 redisTemplate.opsForValue().increment(key); }else{ //超出访问次数 Map<String,Object> errMap=new HashMap<>(); errMap.put("code",400); errMap.put("msg","请求超时，请稍后再试"); render(response,errMap); //这里的CodeMsg是一个返回参数 return false; } } return true; } private void render(HttpServletResponse response, Map<String,Object> errMap) throws Exception { response.setContentType("application/json;charset=UTF-8"); OutputStream out = response.getOutputStream(); String str = JSON.toJSONString(errMap); out.write(str.getBytes("UTF-8")); out.flush(); out.close(); } }
3、将自定义拦截器加入到拦截器列表中
@Configuration public class WebConfig extends WebMvcConfigurerAdapter { @Autowired private FangshuaInterceptor interceptor; @Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(interceptor); } }
最后做一下简单的测试
@RestController @RequestMapping("test") public class TestController { //每三十秒最多可以请求三次，不需要登录 @AccessLimit(seconds=30, maxCount=3, needLogin=false) @PostMapping("/fangshua") public String fangshua(){ return "成功"; } }
