java秒杀之redis限流操作详解

最近写到了一个秒杀的功能模块，为了保证高并发情况下不会宕机，要从多方面去考虑，当前的限流操作只是其中的一个方面，具体操作如下。

导入所需依赖

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <spring.version>5.0.2.RELEASE</spring.version>
    <slf4j.version>1.6.6</slf4j.version>
    <log4j.version>1.2.12</log4j.version>
    <mysql.version>5.1.6</mysql.version>
    <mybatis.version>3.4.5</mybatis.version>
  </properties>

  <dependencies>

    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
      <version>1.6.8</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aop</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>compile</scope>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>${mysql.version}</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.5</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.0</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <!-- log start -->
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>${log4j.version}</version>
    </dependency>

    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>${slf4j.version}</version>
    </dependency>

    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>${slf4j.version}</version>
    </dependency>

    <!-- log end -->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>${mybatis.version}</version>
    </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>1.3.0</version>
    </dependency>

    <dependency>
      <groupId>c3p0</groupId>
      <artifactId>c3p0</artifactId>
      <version>0.9.1.2</version>
      <type>jar</type>
      <scope>compile</scope>
    </dependency>

    <dependency>
      <groupId>org.springframework.data</groupId>
      <artifactId>spring-data-redis</artifactId>
      <version>1.7.2.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>redis.clients</groupId>
      <artifactId>jedis</artifactId>
      <version>2.8.1</version>
    </dependency>
</dependencies>

编写注解

@Retention(RUNTIME)//运行时有效
@Target(ElementType.METHOD)//用在方法上
 public @interface AccessLimit {
     int seconds();//时间范围(单位:秒)
     int maxCount();//在这个时间范围内最大访问次数
 }

编写拦截器

public class AcessLimiitInterceptor implements HandlerInterceptor {
 //注入redisTemplate
    @Autowired
    private RedisTemplate<String,String> redisTemplate;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
     //设置redisTemplate的序列化方式(必须设置为这种方式，因为要用到incr)
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(new StringRedisSerializer());

        if(handler instanceof HandlerMethod){
         //查看该方法上是否有@AcessLimit注解
            HandlerMethod hm= (HandlerMethod) handler;
            AccessLimit accessLimit=hm.getMethodAnnotation(AccessLimit.class);
            //没有@AcessLimit注解，证明无限流操作，直接放行
            if(accessLimit==null){
                return true;
            }
             //获取注解的参数值
            int seconds=accessLimit.seconds();//时间范围
            int maxCount=accessLimit.maxCount();//时间范围内的最大访问次数
            //该请求的路径
            String key=request.getRequestURI();
            //在该时间范围内已经访问的次数
            String countStr=redisTemplate.opsForValue().get(key);
            Integer count=null;
            //如果不是第一次访问，则把访问次数转换为integer类型
            if(countStr!=null){
                count= Integer.valueOf(redisTemplate.opsForValue().get(key));
            }
   //拿到访问次数的过期时间
            Long keySeconds=redisTemplate.getExpire(key);
            //该时间范围内没有访问
            if(count==null){
             //第一次访问，设置key为访问路径，值为访问次数1
                redisTemplate.opsForValue().set(key,1+"");
                //设置过期时间
                redisTemplate.expire(key,600, TimeUnit.SECONDS);
            }else if(count<maxCount){//在该时间范围内已经有访问记录，但访问没有达到最大次数
             //访问次数+1
                redisTemplate.opsForValue().increment(key,1);
                //设置剩余过期时间(修改完该key的value值后，对应的过期时间会失效，需重新设置)
                redisTemplate.expire(key,keySeconds, TimeUnit.SECONDS);
            }else{//在该时间范围内已经超过最大的访问次数
                return false;
            }
        }
        //放行
        return true;
    }
}

编写application.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
 http://www.springframework.org/schema/beans/spring-beans.xsd
 http://www.springframework.org/schema/context
 http://www.springframework.org/schema/context/spring-context.xsd
 http://www.springframework.org/schema/aop
 http://www.springframework.org/schema/aop/spring-aop.xsd
 http://www.springframework.org/schema/tx
 http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!--开启注解的扫描，希望处理service和dao，controller不需要Spring框架去处理-->
    <context:component-scan base-package="cn.itcast" >
        <!--配置哪些注解不扫描-->
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller" />
    </context:component-scan>
    <!--Spring整合MyBatis框架-->
    <!--配置连接池-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="com.mysql.jdbc.Driver"/>
        <property name="jdbcUrl" value="jdbc:mysql:///ssm"/>
        <property name="user" value="root"/>
        <property name="password" value="root"/>
    </bean>

    <!--配置SqlSessionFactory工厂-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
    </bean>

    <!--配置AccountDao接口所在包-->
    <bean id="mapperScanner" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="cn.itcast.dao"/>
    </bean>

    <!--配置Spring框架声明式事务管理-->
    <!--配置事务管理器-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource" />
    </bean>

    <!--配置事务通知-->
    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="find*" read-only="true"/>
            <tx:method name="*" isolation="DEFAULT"/>
        </tx:attributes>
    </tx:advice>

    <!--配置AOP增强-->
    <aop:config>
        <aop:advisor advice-ref="txAdvice" pointcut="execution(* cn.itcast.service.impl.*ServiceImpl.*(..))"/>
    </aop:config>

    <context:property-placeholder location="classpath*:*.properties"></context:property-placeholder>
    <!-- <context:property-placeholder location="classpath*:properties/*.properties" />   -->

    <!-- redis 相关配置 -->
    <bean id="poolConfig" class="redis.clients.jedis.JedisPoolConfig">
        <property name="maxIdle" value="${redis.maxIdle}" />
        <property name="maxWaitMillis" value="${redis.maxWait}" />
        <property name="testOnBorrow" value="${redis.testOnBorrow}" />
    </bean>

    <bean id="JedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"
          p:host-name="${redis.host}" p:port="${redis.port}" p:password="${redis.pass}" p:pool-config-ref="poolConfig"/>

    <bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate">
        <property name="connectionFactory" ref="JedisConnectionFactory" />
    </bean>

</beans>

配置web.xml

<web-app>
  <display-name>Archetype Created Web Application</display-name>

  <!--配置Spring的监听器，默认只加载WEB-INF目录下的applicationContext.xml配置文件-->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  <!--设置配置文件的路径-->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext.xml</param-value>
  </context-param>

  <!--配置前端控制器-->
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--加载springmvc.xml配置文件-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
    <!--启动服务器，创建该servlet-->
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!--解决中文乱码的过滤器-->
  <filter>
    <filter-name>characterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>characterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

</web-app>

注解应用

@AccessLimit(seconds = 500,maxCount = 3)
    @RequestMapping(value = "/findAll")
    public String findAll(Model model){
        System.out.println("csl");
        return "list";
    }

总 结

以上操作就完成了java后台使用redisTemplate的限流操作，这里还需各位自己开启一个redis服务端并且把配置文件中的地址改成对应的ip，希望以上内容对大家有帮助，多提宝贵意见。

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