LIMIT 子句可以被用于强制 SELECT 语句返回指定的记录数。LIMIT 接受一个或两个数字参数。参数必须是一个整数常量。如果给定两个参数，第一个参数指定第一个返回记录行的偏移量，第二个参数指定返回记录行的最大数目。初始记录行的偏移量是 0(而不是 1)： 为了与 PostgreSQL 兼容，MySQL 也支持句法： LIMIT # OFFSET #。

package com.programb.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class SpringBootLimitApplication {public static void main(String[] args) {SpringApplication.run(SpringBootLimitApplication.class, args);}
}

package com.programb.example.annotation;import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface RateLimit {String key() default "";int time();int count();
}

package com.programb.example.config;import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import org.springframework.scripting.support.ResourceScriptSource;
import org.springframework.stereotype.Component;import java.io.Serializable;@Component
public class Commons {@Beanpublic DefaultRedisScript<Number> redisluaScript() {DefaultRedisScript<Number> redisScript = new DefaultRedisScript<>();redisScript.setScriptSource(new ResourceScriptSource(new ClassPathResource("rateLimit.lua")));redisScript.setResultType(Number.class);return redisScript;}@Beanpublic RedisTemplate<String, Serializable> limitRedisTemplate(LettuceConnectionFactory redisConnectionFactory) {RedisTemplate<String, Serializable> template = new RedisTemplate<String, Serializable>();template.setKeySerializer(new StringRedisSerializer());template.setValueSerializer(new GenericJackson2JsonRedisSerializer());template.setConnectionFactory(redisConnectionFactory);return template;}}

package com.programb.example.config;import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;import com.programb.example.annotation.RateLimit;import javax.servlet.http.HttpServletRequest;
import java.io.Serializable;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.List;@Aspect
@Configuration
public class LimitAspect {private static final Logger logger = LoggerFactory.getLogger(LimitAspect.class);@Autowiredprivate RedisTemplate<String, Serializable> limitRedisTemplate;@Autowiredprivate DefaultRedisScript<Number> redisluaScript;@Around("execution(* com.souyunku.example.controller ..*(..) )")public Object interceptor(ProceedingJoinPoint joinPoint) throws Throwable {MethodSignature signature = (MethodSignature) joinPoint.getSignature();Method method = signature.getMethod();Class<?> targetClass = method.getDeclaringClass();RateLimit rateLimit = method.getAnnotation(RateLimit.class);if (rateLimit != null) {HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();String ipAddress = getIpAddr(request);StringBuffer stringBuffer = new StringBuffer();stringBuffer.append(ipAddress).append("-").append(targetClass.getName()).append("- ").append(method.getName()).append("-").append(rateLimit.key());List<String> keys = Collections.singletonList(stringBuffer.toString());Number number = limitRedisTemplate.execute(redisluaScript, keys, rateLimit.count(), rateLimit.time());if (number != null && number.intValue() != 0 && number.intValue() <= rateLimit.count()) {logger.info("限流时间段内访问第：{} 次", number.toString());return joinPoint.proceed();}} else {return joinPoint.proceed();}throw new RuntimeException("已经到设置限流次数");}public static String getIpAddr(HttpServletRequest request) {String ipAddress = null;try {ipAddress = request.getHeader("x-forwarded-for");if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {ipAddress = request.getHeader("Proxy-Client-IP");}if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {ipAddress = request.getHeader("WL-Proxy-Client-IP");}if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {ipAddress = request.getRemoteAddr();}// 对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割if (ipAddress != null && ipAddress.length() > 15) { // = 15if (ipAddress.indexOf(",") > 0) {ipAddress = ipAddress.substring(0, ipAddress.indexOf(","));}}} catch (Exception e) {ipAddress = "";}return ipAddress;}
}

package com.programb.example.controller;import org.apache.commons.lang3.time.DateFormatUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.support.atomic.RedisAtomicInteger;
import org.springframework.data.redis.support.atomic.RedisAtomicLong;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;import com.programb.example.annotation.RateLimit;import java.util.Date;@RestController
public class LimiterController {@Autowiredprivate RedisTemplate redisTemplate;@RateLimit(key = "test", time = 10, count = 10)@GetMapping("/test")public String luaLimiter() {RedisAtomicInteger entityIdCounter = new RedisAtomicInteger("entityIdCounter", redisTemplate.getConnectionFactory());String date = DateFormatUtils.format(new Date(), "yyyy-MM-dd HH:mm:ss.SSS");return date + " 累计访问次数：" + entityIdCounter.getAndIncrement();}
}

spring.application.name=spring-boot-limitspring.redis.database=0spring.redis.host=127.0.0.1spring.redis.port=6379spring.redis.password=spring.redis.jedis.pool.max-active=8spring.redis.jedis.pool.max-wait=-1spring.redis.jedis.pool.max-idle=8spring.redis.jedis.pool.min-idle=0spring.redis.timeout=10000

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.programb.example</groupId><artifactId>spring-boot-limit</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>spring-boot-limit</name><description>Demo project for Spring Boot</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.0.4.RELEASE</version><relativePath/> </parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-aop</artifactId></dependency><dependency><groupId>org.apache.commons</groupId><artifactId>commons-lang3</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>