Using Redis with Spring

            
<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.example.spring</groupid>
 <artifactid>redis</artifactid>
 <version>0.0.1-SNAPSHOT</version>
 <packaging>jar</packaging>

 <properties>
  <project.build.sourceencoding>UTF-8</project.build.sourceencoding>
  <spring.version>3.1.0.RELEASE</spring.version>
 </properties>

 <dependencies>
  <dependency>
   <groupid>org.springframework.data</groupid>
   <artifactid>spring-data-redis</artifactid>
   <version>1.0.0.RELEASE</version>
  </dependency>

  <dependency>
   <groupid>cglib</groupid>
   <artifactid>cglib-nodep</artifactid>
   <version>2.2</version>
  </dependency>

  <dependency>
   <groupid>log4j</groupid>
   <artifactid>log4j</artifactid>
   <version>1.2.16</version>
  </dependency>

  <dependency>
   <groupid>redis.clients</groupid>
   <artifactid>jedis</artifactid>
   <version>2.0.0</version>
   <type>jar</type>
  </dependency>

  <dependency>
   <groupid>org.springframework</groupid>
   <artifactid>spring-core</artifactid>
   <version>${spring.version}</version>
  </dependency>

  <dependency>
   <groupid>org.springframework</groupid>
   <artifactid>spring-context</artifactid>
   <version>${spring.version}</version>
  </dependency>
 </dependencies>
</project>

package com.example.redis.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.GenericToStringSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

@Configuration
public class AppConfig {
 @Bean
 JedisConnectionFactory jedisConnectionFactory() {
  return new JedisConnectionFactory();
 }

 @Bean
 RedisTemplate< String, Object > redisTemplate() {
  final RedisTemplate< String, Object > template =  new RedisTemplate< String, Object >();
  template.setConnectionFactory( jedisConnectionFactory() );
  template.setKeySerializer( new StringRedisSerializer() );
  template.setHashValueSerializer( new GenericToStringSerializer< Object >( Object.class ) );
  template.setValueSerializer( new GenericToStringSerializer< Object >( Object.class ) );
  return template;
 }
}

@Autowired private RedisTemplate< String, Object > template;

public Object getValue( final String key ) {
    return template.opsForValue().get( key );
}

public void setValue( final String key, final String value ) {
    template.opsForValue().set( key, value );
}

Optionally, the key could be set to expire (yet another useful feature of Redis), f.e. let our keys expire in 1 second:

public void setValue( final String key, final String value ) {
    template.opsForValue().set( key, value );
    template.expire( key, 1, TimeUnit.SECONDS );
}

Arbitrary objects could be saved into Redis as hashes (maps), f.e. let save instance of some class User

public class User {
 private final Long id;
 private String name;
 private String email;
       
    // Setters and getters are omitted for simplicity
}

into Redis using key pattern “user:<id>”:

public void setUser( final User user ) {
 final String key = String.format( "user:%s", user.getId() );
 final Map< String, Object > properties = new HashMap< String, Object >();

 properties.put( "id", user.getId() );
 properties.put( "name", user.getName() );
 properties.put( "email", user.getEmail() );

 template.opsForHash().putAll( key, properties);
}

Respectively, object could easily be inspected and retrieved using the id.

public User getUser( final Long id ) {
 final String key = String.format( "user:%s", id );

 final String name = ( String )template.opsForHash().get( key, "name" );
 final String email = ( String )template.opsForHash().get( key, "email" );

 return new User( id, name, email );
}

@Bean
MessageListenerAdapter messageListener() {
 return new MessageListenerAdapter( new RedisMessageListener() );
}

@Bean
RedisMessageListenerContainer redisContainer() {
 final RedisMessageListenerContainer container = new RedisMessageListenerContainer();

 container.setConnectionFactory( jedisConnectionFactory() );
 container.addMessageListener( messageListener(), new ChannelTopic( "my-queue" ) );

 return container;
}

package com.example.redis.impl;

import org.springframework.data.redis.connection.Message;
import org.springframework.data.redis.connection.MessageListener;

public class RedisMessageListener implements MessageListener {
 @Override
 public void onMessage(Message message, byte[] paramArrayOfByte) {
  System.out.println( "Received by RedisMessageListener: " + message.toString() );
 }
}

@Autowired private RedisTemplate< String, Object > template;

public void publish( final String message ) {
 template.execute(
  new RedisCallback< Long >() {
   @SuppressWarnings( "unchecked" )
   @Override
   public Long doInRedis( RedisConnection connection ) throws DataAccessException {
    return connection.publish(
     ( ( RedisSerializer< String > )template.getKeySerializer() ).serialize( "queue" ),
     ( ( RedisSerializer< Object > )template.getValueSerializer() ).serialize( message ) );
   }
  }
 );
}

That’s basically it for very quick introduction but definitely enough to fall in love with Redis.

Reference: Using Redis with Spring from our JCG partner Andrey Redko at the Andriy Redko {devmind} blog.