Hi,
A few example on how to handle Redis usage with Spring Boot. Also some examples on how to error handle exceptions and issues with Redis.
The code below will help you initialize your redis connect and how to use it. One thing to take notice is that redis keys are global so you must make sure that any method parameter you use with you keys and unique. For this reason below you have samples of custom key generators.
Redis Samples
Redis main configurations
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.*;
import org.springframework.cache.interceptor.CacheErrorHandler;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.context.annotation.*;
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;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import org.springframework.util.StringUtils;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
@Configuration
@ComponentScan
@EnableCaching
@Profile({"dev","test"})
public class RedisCacheConfig extends CachingConfigurerSupport {
@Override
public CacheErrorHandler errorHandler() {
return new CustomCacheErrorHandler();
}
protected final org.slf4j.Logger logger = LoggerFactory.getLogger(RedisCacheConfig.class);
// This is a custom default keygenerator that is used if no other explicit key generator is specified
@Bean
public KeyGenerator keyGenerator() {
return new KeyGenerator() {
protected final org.slf4j.Logger logger = LoggerFactory.getLogger(RedisCacheConfig.class);
@Override
public Object generate(Object o, Method method, Object... objects) {
return RedisCacheConfig.keyGeneratorProcessor(logger, o, method, null, objects);
}
};
}
// A custom key generator that generates a key based on the first method parameter while ignoring all other parameters
@Bean("keyGeneratorFirstParamKey")
public KeyGenerator keyGeneratorFirstParamKey() {
return new KeyGenerator() {
protected final org.slf4j.Logger logger = LoggerFactory.getLogger(RedisCacheConfig.class);
@Override
public Object generate(Object o, Method method, Object... objects) {
return RedisCacheConfig.keyGeneratorProcessor(logger, o, method, 0, objects);
}
};
}
// A custom key generator that generates a key based on the second method parameter while ignoring all other parameters
@Bean("keyGeneratorSecondParamKey")
public KeyGenerator keyGeneratorSecondParamKey() {
return new KeyGenerator() {
protected final org.slf4j.Logger logger = LoggerFactory.getLogger(RedisCacheConfig.class);
@Override
public Object generate(Object o, Method method, Object... objects) {
return RedisCacheConfig.keyGeneratorProcessor(logger, o, method, 1, objects);
}
};
}
// This is the main logic for creating cache keys
public static String keyGeneratorProcessor(org.slf4j.Logger logger, Object o, Method method, Integer keyIndex, Object... objects) {
// Retrieve all cache names for each anonation and compose a cache key prefix
CachePut cachePutAnnotation = method.getAnnotation(CachePut.class);
Cacheable cacheableAnnotation = method.getAnnotation(Cacheable.class);
CacheEvict cacheEvictAnnotation = method.getAnnotation(CacheEvict.class);
org.springframework.cache.annotation.CacheConfig cacheConfigClassAnnotation = o.getClass().getAnnotation(org.springframework.cache.annotation.CacheConfig.class);
String keyPrefix = "";
String[] cacheNames = null;
if (cacheConfigClassAnnotation != null)
cacheNames = cacheConfigClassAnnotation.cacheNames();
if (cacheEvictAnnotation != null)
if (cacheEvictAnnotation.value() != null)
if (cacheEvictAnnotation.value().length > 0)
cacheNames = org.apache.commons.lang3.ArrayUtils.addAll(cacheNames, cacheEvictAnnotation.value());
if (cachePutAnnotation != null)
if (cachePutAnnotation.value() != null)
if (cachePutAnnotation.value().length > 0)
cacheNames = org.apache.commons.lang3.ArrayUtils.addAll(cacheNames, cachePutAnnotation.value());
if (cacheableAnnotation != null)
if (cacheableAnnotation.value() != null)
if (cacheableAnnotation.value().length > 0)
cacheNames = org.apache.commons.lang3.ArrayUtils.addAll(cacheNames, cacheableAnnotation.value());
if (cacheNames != null)
if (cacheNames.length > 0) {
for (String cacheName : cacheNames)
keyPrefix += cacheName + "_";
}
StringBuilder sb = new StringBuilder();
int parameterIndex = 0;
for (Object obj : objects) {
if (obj != null && !StringUtils.isEmpty(obj.toString())) {
if (keyIndex == null)
sb.append(obj.toString());
else if (parameterIndex == keyIndex) {
sb.append(obj.toString());
break;
}
}
parameterIndex++;
}
String fullKey = keyPrefix + sb.toString();
logger.debug("REDIS KEYGEN for CacheNames: " + keyPrefix + " with KEY: " + fullKey);
return fullKey;
//---------------------------------------------------------------------------------------------------------
// Another example how to do custom cache keys
// This will generate a unique key of the class name, the method name,
// and all method parameters appended.
/*StringBuilder sb = new StringBuilder();
sb.append(o.getClass().getName());
sb.append("-" + method.getName() );
for (Object obj : objects) {
if(obj != null)
sb.append("-" + obj.toString());
}
if(logger.isDebugEnabled())
logger.debug("REDIS KEYGEN: " + sb.toString());
return sb.toString();*/
}
// Create the redis connection here
@Bean
public JedisConnectionFactory jedisConnectionFactory() {
JedisConnectionFactory jedisConFactory = new JedisConnectionFactory();
jedisConFactory.setUseSsl(true);
jedisConFactory.setHostName("127.0.0.1");
jedisConFactory.setPort(6379);
if (!StringUtils.isEmpty(mytoken)) {
jedisConFactory.setPassword(mytoken);
}
jedisConFactory.setUsePool(true);
jedisConFactory.afterPropertiesSet();
return jedisConFactory;
}
@Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
@Bean
public RedisTemplate redisTemplate() {
RedisTemplate redisTemplate = new RedisTemplate();
redisTemplate.setConnectionFactory(jedisConnectionFactory());
redisTemplate.setKeySerializer(new StringRedisSerializer());
return redisTemplate;
}
// Cache configurations like how long data is cached
@Bean
public CacheManager cacheManager(RedisTemplate redisTemplate) {
RedisCacheManager cacheManager = new RedisCacheManager(redisTemplate);
Map cacheExpiration = new HashMap();
cacheExpiration.put("USERS", 120);
cacheExpiration.put("CARS", 3600):
// Number of seconds before expiration. Defaults to unlimited (0)
cacheManager.setDefaultExpiration(60);
cacheManager.setExpires(cacheExpiration);
return cacheManager;
}
}
Redis Error/Exception Handling
public class CustomCacheErrorHandler implements CacheErrorHandler {
protected final org.slf4j.Logger logger = LoggerFactory.getLogger(this.getClass());
protected Gson gson = new GsonBuilder().create();
@Override
public void handleCacheGetError(RuntimeException exception,
Cache cache, Object key) {
logger.error("Error in REDIS GET operation for KEY: " + key, exception);
try
{
if (cache.get(key) != null && logger.isDebugEnabled())
logger.debug("Possible existing data which for the cache GET operation in REDIS Cache by KEY: " + key + " with TYPE: " + cache.get(key).get().getClass() + " and DATA: " + this.gson.toJson(cache.get(key).get()));
} catch (Exception ex)
{
// NOTICE: This exception is not logged because this might occur because the cache connection is not established.
// So if the initial exception that was thrown might have been the same, no connection to the cache server.
// In such a case this is logged in above already, before the try catch.
}
}
@Override
public void handleCachePutError(RuntimeException exception, Cache cache,
Object key, Object value) {
logger.error("Error in REDIS PUT operation for KEY: " + key, exception);
if(logger.isDebugEnabled())
logger.debug("Error in REDIS PUT operation for KEY: " + key + " with TYPE: " + value.getClass() + " and DATA: " + this.gson.toJson(value), exception);
}
@Override
public void handleCacheEvictError(RuntimeException exception, Cache cache,
Object key) {
logger.error("Error in REDIS EVICT operation for KEY: " + key, exception);
try
{
if (cache.get(key) != null && logger.isDebugEnabled())
logger.debug("Possible existing data which for the cache EVICT operation in REDIS Cache by KEY: " + key + " with TYPE: " + cache.get(key).get().getClass() + " and DATA: " + this.gson.toJson(cache.get(key).get()));
} catch (Exception ex)
{
// NOTICE: This exception is not logged because this might occur because the cache connection is not established.
// So if the initial exception that was thrown might have been the same, no connection to the cache server.
// In such a case this is logged in above already, before the try catch.
}
}
@Override
public void handleCacheClearError(RuntimeException exception,Cache cache){
logger.error("Error in REDIS CLEAR operation ", exception);
}
}
Custom Key Generator Example
@Cacheable(value = "USERS", keyGenerator = "keyGeneratorFirstParamKey")
public UserData getUsers(String userId, Object data)
{
// Do something here
}
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