使用Spring Data +Redis实现缓存


首先，我们给一个服务配置Cache，如下：
@Service('helloService')

public class HelloServiceImpl implements HelloService {

    /**

     * Using SpEL for conditional caching - only cache method executions when

     * the name is equal to 'Joshua'

     */

    @Cacheable(value='messageCache', condition=''Joshua'.equals(#name)')

    public String getMessage(String name) {

        System.out.println('Executing HelloServiceImpl' +

                        '.getHelloMessage(\'' + name + '\')');

        return 'Hello ' + name + '!';

    }

}

使用 Jedis 作为Redis的Java客户端，在Spring只要配置三个：

JedisConnectionFactory 有以下参数：

hostName=”localhost”
port=6379
timeout=2000 ms
database=0
usePool=true

 
RedisTemplate是提供你使用连接池连接，使用JdkSerializationRedisSerializer序列化。

RedisCacheManager 是依赖RedisTemplate提供一个cache接口。

<?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:c='http://www.springframework.org/schema/c'

    xmlns:p='http://www.springframework.org/schema/p'

    xmlns:cache='http://www.springframework.org/schema/cache'

    xsi:schemaLocation='
http://www.springframework.org/schema/beansvhttp://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/cache http://www.springframework.org/schema/cache/spring-cache.xsd'>

    <context:component-scan base-package='com.joshuawhite.example.service' />

    <context:property-placeholder location='classpath:/redis.properties'/>

    <!-- turn on declarative caching -->

    <cache:annotation-driven />

    <!-- Jedis ConnectionFactory -->

    <bean

        id='jedisConnectionFactory'

        class='org.springframework.data.redis.connection.jedis.JedisConnectionFactory'

        p:host-name='${redis.host-name}'

        p:port='${redis.port}'

        p:use-pool='true'/>

    <!-- redis template definition -->

    <bean

        id='redisTemplate'

        class='org.springframework.data.redis.core.RedisTemplate'

        p:connection-factory-ref='jedisConnectionFactory'/>

    <!-- declare Redis Cache Manager -->

    <bean

        id='cacheManager'

        class='org.springframework.data.redis.cache.RedisCacheManager'

        c:template-ref='redisTemplate'/>

</beans>

使用Java配置等同于上面配置，

package com.joshuawhite.example.config;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.cache.CacheManager;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.ComponentScan;

import org.springframework.context.annotation.Configuration;

import org.springframework.context.annotation.PropertySource;

import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;

import org.springframework.data.redis.cache.RedisCacheManager;

import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;

import org.springframework.data.redis.core.RedisTemplate;

@Configuration

@ComponentScan('com.joshuawhite.example')

@PropertySource('classpath:/redis.properties')

public class AppConfig {

 private @Value('${redis.host-name}') String redisHostName;

 private @Value('${redis.port}') int redisPort;

 @Bean

 public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {

     return new PropertySourcesPlaceholderConfigurer();

 }

 @Bean

 JedisConnectionFactory jedisConnectionFactory() {

     JedisConnectionFactory factory = new JedisConnectionFactory();

     factory.setHostName(redisHostName);

     factory.setPort(redisPort);

     factory.setUsePool(true);

     return factory;

 }

 @Bean

 RedisTemplate<Object, Object> redisTemplate() {

     RedisTemplate<Object, Object> redisTemplate = new RedisTemplate<Object, Object>();

     redisTemplate.setConnectionFactory(jedisConnectionFactory());

     return redisTemplate;

 }

 @Bean

 CacheManager cacheManager() {

     return new RedisCacheManager(redisTemplate());

 }

}

下面是客户端调用代码：

public class App {

    public static void main(String[] args) {

        boolean useJavaConfig  = true;

        ApplicationContext ctx = null;

        //Showing examples of both Xml and Java based configuration

        if (useJavaConfig ) {

                ctx = new AnnotationConfigApplicationContext(AppConfig.class);

        }

        else {

                ctx = new GenericXmlApplicationContext('/META-INF/spring/app-context.xml');

        }

        HelloService helloService = ctx.getBean('helloService', HelloService.class);

        //First method execution using key='Josh', not cached

        System.out.println('message: ' + helloService.getMessage('Josh'));

        //Second method execution using key='Josh', still not cached

        System.out.println('message: ' + helloService.getMessage('Josh'));

        //First method execution using key='Joshua', not cached

        System.out.println('message: ' + helloService.getMessage('Joshua'));

        //Second method execution using key='Joshua', cached

        System.out.println('message: ' + helloService.getMessage('Joshua'));

        System.out.println('Done.');

    }

}

运行输出：

Executing HelloServiceImpl.getHelloMessage('Josh')

message: Hello Josh!

Executing HelloServiceImpl.getHelloMessage('Josh')

message: Hello Josh!

Executing HelloServiceImpl.getHelloMessage('Joshua')

message: Hello Joshua!

Executing HelloServiceImpl.getHelloMessage('Joshua')

message: Hello Joshua!

Done.