自定义 AccessLimit 注解实现 Spring Boot 接口防刷

╰半夏微凉° 2022-09-11 04:19 166阅读 0赞

### 技术要点：Spring 基础 ###

**首先是写一个注解类：**

import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    @Retention(RetentionPolicy.RUNTIME)
    @Target(ElementType.METHOD)
    public @interface AccessLimit { 
        
        int seconds();
        int maxCount();
        boolean needLogin() default false;
    }

**接着就是在Interceptor拦截器中实现：**

import org.springframework.stereotype.Component;
    import org.springframework.web.method.HandlerMethod;
    import org.springframework.web.servlet.HandlerInterceptor;
    import per.sanchar.annotation.AccessLimit;
    import per.sanchar.util.MemoryCacheUtils;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.OutputStream;
    import java.util.Objects;
    
    @Component
    public class ApiProtectedInterceptor implements HandlerInterceptor { 
    
        public static final String ACCESS_LIMIT_REACHED = "ACCESS_LIMIT_REACHED";
    
        @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;
                AccessLimit accessLimit = hm.getMethodAnnotation(AccessLimit.class);
                if (Objects.isNull(accessLimit)) { 
                    return true;
                }
                int seconds = accessLimit.seconds();
                int maxCount = accessLimit.maxCount();
                boolean needLogin = accessLimit.needLogin();
                String key = request.getRequestURI();
                // 如果需要登录
                if (needLogin) { 
                    // 获取登录的session进行判断
                    // ......
                    //这里假设用户是1,项目中是动态获取的userId
                    key += "1";
                }
                // 从memory cache中获取用户访问的次数，项目中建议用redis或者其它缓存数据库
                Integer count = MemoryCacheUtils.getData(key);
                if (Objects.isNull(count)) { 
                    // 第一次访问
                    MemoryCacheUtils.setData(key, 1, seconds * 1000);
                } else if (count < maxCount) { 
                    MemoryCacheUtils.setData(key, count + 1, seconds * 1000);
                } else { 
                    //超出访问次数
                    render(response, ACCESS_LIMIT_REACHED);
                    return false;
                }
            }
            return true;
        }
    
        private void render(HttpServletResponse response, String msg) throws Exception { 
            response.setContentType("application/json;charset=UTF-8");
            OutputStream out = response.getOutputStream();
            out.write(msg.getBytes("UTF-8"));
            out.flush();
            out.close();
        }
    }

**再把Interceptor注册到springboot中：**

import org.springframework.context.annotation.Configuration;
    import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
    import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
    import per.sanchar.interceptor.ApiProtectedInterceptor;
    
    import javax.annotation.Resource;
    
    @Configuration
    public class WebConfig extends WebMvcConfigurerAdapter { 
    
        @Resource
        private ApiProtectedInterceptor apiProtectedInterceptor;
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) { 
            registry.addInterceptor(apiProtectedInterceptor);
        }
    }

**接着在Controller中加入注解：**

import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    import per.sanchar.annotation.AccessLimit;
    
    @RestController
    public class DemoController { 
    
        @AccessLimit(seconds = 5, maxCount = 5, needLogin = true)
        @RequestMapping("/test")
        public String test() { 
            return "success";
        }
    }