RedisCacheManager设置Value序列化器技巧

CacheManager基本配置

　　请参考博文：springboot2.0 redis EnableCaching的配置和使用

RedisCacheManager构造函数

/*** Construct a {@link RedisCacheManager}.* * @param redisOperations*/
@SuppressWarnings("rawtypes")
public RedisCacheManager(RedisOperations redisOperations) {this(redisOperations, Collections.<String> emptyList());
}/*** Construct a static {@link RedisCacheManager}, managing caches for the specified cache names only.* * @param redisOperations* @param cacheNames* @since 1.2*/
@SuppressWarnings("rawtypes")
public RedisCacheManager(RedisOperations redisOperations, Collection<String> cacheNames) {this.redisOperations = redisOperations;setCacheNames(cacheNames);
}

　　RedisCacheManager需要一个 RedisOperations实例，一般是RedisTemplate。还有一个不必须的缓存名称集合参数。

protected RedisCache createCache(String cacheName) {long expiration = computeExpiration(cacheName);return new RedisCache(cacheName, (usePrefix ? cachePrefix.prefix(cacheName) : null), redisOperations, expiration);
}

　　在创建缓存时，通过RedisCache的构造函数传入 redisOperations（即RedisTemplate实例）。

设置全局通用的序列化器

　　GenericJackson2JsonRedisSerializer

import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;

GenericJackson2JsonRedisSerializer serializer = new GenericJackson2JsonRedisSerializer();
User user = new User();
user.setName("hjzgg");
user.setAge(26);System.out.println(serializer.deserialize(serializer.serialize(user)));public static class User {private String name;private Integer age;public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}@Overridepublic String toString() {return Objects.toStringHelper(this).add("name", name).add("age", age).toString();}
}

　　调试发现，序列化内容加入了对象的类型信息，如下。

　　查看GenericJackson2JsonRedisSerializer构造函数，序列化和反序列化的实现是通过Jackson的ObjectMapper完成的。并开启了默认类型的配置。

/*** Creates {@link GenericJackson2JsonRedisSerializer} and configures {@link ObjectMapper} for default typing using the* given {@literal name}. In case of an {@literal empty} or {@literal null} String the default* {@link JsonTypeInfo.Id#CLASS} will be used.* * @param classPropertyTypeName Name of the JSON property holding type information. Can be {@literal null}.*/
public GenericJackson2JsonRedisSerializer(String classPropertyTypeName) {this(new ObjectMapper());if (StringUtils.hasText(classPropertyTypeName)) {mapper.enableDefaultTypingAsProperty(DefaultTyping.NON_FINAL, classPropertyTypeName);} else {mapper.enableDefaultTyping(DefaultTyping.NON_FINAL, As.PROPERTY);}
}

　　Protostuff序列化和反序列化

import com.dyuproject.protostuff.LinkedBuffer;
import com.dyuproject.protostuff.ProtostuffIOUtil;
import com.dyuproject.protostuff.Schema;
import com.dyuproject.protostuff.runtime.RuntimeSchema;
import org.springframework.data.redis.serializer.RedisSerializer;public class ProtostuffRedisSerializer implements RedisSerializer<Object> {private static final Schema<ObjectWrapper> schema = RuntimeSchema.getSchema(ObjectWrapper.class);public ProtostuffRedisSerializer() {}public byte[] serialize(Object object) {if (object == null) {return new byte[0];} else {LinkedBuffer buffer = LinkedBuffer.allocate(512);byte[] var3;try {var3 = ProtostuffIOUtil.toByteArray(new ObjectWrapper(object), schema, buffer);} finally {buffer.clear();}return var3;}}public Object deserialize(byte[] bytes) {if (bytes != null && bytes.length != 0) {try {ObjectWrapper objectWrapper = new ObjectWrapper();ProtostuffIOUtil.mergeFrom(bytes, objectWrapper, schema);return objectWrapper.getObject();} catch (Exception var3) {throw new RuntimeException(var3.getMessage(), var3);}} else {return null;}}
}public class ObjectWrapper {private Object object;public ObjectWrapper(Object object) {this.object = object;}public ObjectWrapper() {}public Object getObject() {return this.object;}public void setObject(Object object) {this.object = object;}
}

　　上面通过Protostuff自定义了一个序列化和反序列化的工具，测试代码如下。

    ProtostuffRedisSerializer serializer = new ProtostuffRedisSerializer();Person person = new Person();person.setName("hjzgg");person.setAge(26);System.out.println(serializer.deserialize(serializer.serialize(person)));
}public static class Person {private String name;private int age;public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Person{" +"name='" + name + '\'' +", age=" + age +'}';}
}

　　调试发现，序列化内容加入了对象的类型信息，如下。

　　JdkSerializationRedisSerializer

JdkSerializationRedisSerializer serializer = new JdkSerializationRedisSerializer();
User user = new User();
user.setName("hjzgg");
user.setAge(26);System.out.println(serializer.deserialize(serializer.serialize(user)));public static class User implements Serializable {private String name;private Integer age;public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}@Overridepublic String toString() {return Objects.toStringHelper(this).add("name", name).add("age", age).toString();}
}

　　JdkSerializationRedisSerializer构造函数如下，序列转换器和反序列转换器。

/*** Creates a new {@link JdkSerializationRedisSerializer} using the default class loader.*/
public JdkSerializationRedisSerializer() {this(new SerializingConverter(), new DeserializingConverter());
}

　　发现JdkSerializationRedisSerializer内部使用的是我们最熟悉的ObjectInputStream和ObjectOutputStream。

　　调试发现，序列化内容加入了对象的类型信息，如下。

　　要缓存的 Java 对象必须实现 Serializable 接口，因为 Spring 会将对象先序列化再存入 Redis，比如本文中的 User 类，如果不实现 Serializable 的话将会遇到类似这种错误：nested exception is java.lang.IllegalArgumentException: DefaultSerializer requires a Serializable payload but received an object of type [com.XXX.User]]。

不同cache设置不同序列化器

　　Jackson2JsonRedisSerializer

import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;

Jackson2JsonRedisSerializer<?> serializer1 = new Jackson2JsonRedisSerializer<>(JacksonHelper.genJavaType(User.class));
System.out.println(serializer1.deserialize(serializer1.serialize(user)));public static class User {private String name;private Integer age;public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}@Overridepublic String toString() {return Objects.toStringHelper(this).add("name", name).add("age", age).toString();}
}

　　Jackson2JsonRedisSerializer内部序列化过程也是通过Jackson ObjectMapper来完成的，但是序列化内容不包含对象类型信息，如下。

　　所以，在使用Jackson2JsonRedisSerializer的时候需要指定当前cache存储的对象类型。

　　自定义RedisCacheManager

　　实现不同RedisCache对应不同的RedisTemplate（即对应不同的序列化器）

static class CustomRedisCacheManager extends RedisCacheManager {private Map<String, RedisCache> redisCaches = Maps.newConcurrentMap();public static final String CACHE_NAME_DEFAULT = "DEFAULT_CACHE";public CustomRedisCacheManager(Map<String, CustomRedisConfiguration> configurations) {super(configurations.get(CACHE_NAME_DEFAULT).getRedisTemplate(), configurations.keySet());configurations.keySet().stream().forEach(cacheName -> redisCaches.put(cacheName, new RedisCache(cacheName, null, configurations.get(cacheName).getRedisTemplate(), configurations.get(cacheName).duration.getSeconds())));}@Overridepublic Cache getCache(String cacheName) {return redisCaches.get(cacheName);}
}

　　RedisCacheManager 通过加载自定义配置实现类RedisCacheConfigurationProvider获取不同RedisCache的配置

@Bean
@Primary
public RedisCacheManager redisCacheManager(RedisTemplate redisTemplate, ObjectProvider<RedisCacheConfigurationProvider> provider) {Map<String, CustomRedisConfiguration> configurations = Maps.newHashMap();configurations.put(CustomRedisCacheManager.CACHE_NAME_DEFAULT, new CustomRedisConfiguration(redisTemplate, Duration.ofMinutes(20)));RedisCacheConfigurationProvider configurationProvider = provider.getIfAvailable();if (!Objects.isNull(configurationProvider)) {configurations.putAll(configurationProvider.resolve(redisTemplate.getConnectionFactory()));}RedisCacheManager cacheManager = new CustomRedisCacheManager(configurations);return cacheManager;
}

　　RedisCache自定义配置提供者抽象类，根据不同的缓存类型设置不同的序列化器

public static abstract class RedisCacheConfigurationProvider {// key = 缓存名称， value = 缓存时间 和 缓存类型protected Map<String, Pair<Duration, JavaType>> configs;protected abstract void initConfigs();public Map<String, CustomRedisConfiguration> resolve(RedisConnectionFactory connectionFactory) {initConfigs();Assert.notEmpty(configs, "RedisCacheConfigurationProvider 配置不能为空...");Map<String, CustomRedisConfiguration> result = Maps.newHashMap();configs.forEach((cacheName, pair) -> {RedisTemplate<?, ?> redisTemplate = new RedisTemplate<>();redisTemplate.setConnectionFactory(connectionFactory);redisTemplate.setKeySerializer(new JdkSerializationRedisSerializer());redisTemplate.setValueSerializer(new Jackson2JsonRedisSerializer<>(pair.getValue()));redisTemplate.afterPropertiesSet();result.put(cacheName, new CustomRedisConfiguration(redisTemplate, pair.getKey()));});return result;}
}

　　用户根据缓存名称设置不同的存储类型

@Component
public class CouponRedisCacheConfigurationProvider extends RedisCacheConfig.RedisCacheConfigurationProvider {@Overrideprotected void initConfigs() {this.configs = Maps.newHashMap();this.configs.put(CouponConstants.COUPON_ALL_CACHE, new Pair<>(Duration.ofHours(12), JacksonHelper.genMapType(HashMap.class, String.class, Coupon.class)));this.configs.put(CouponConstants.COUPON_GOOD_CACHE, new Pair<>(Duration.ofHours(12), JacksonHelper.genCollectionType(List.class, String.class)));this.configs.put(CouponConstants.COUPON_HANDLE_TELEPHONE_STATUS_CACHE, new Pair<>(Duration.ofHours(1), JacksonHelper.genCollectionType(List.class, CouponHandle.class)));this.configs.put(CouponConstants.COUPON_HANDLE_TELEPHONE_GOOD_CACHE, new Pair<>(Duration.ofHours(1), JacksonHelper.genJavaType(CompositeCouponHandle.class)));}
}

　　CompositeCacheManager

　　复合CacheManager实现了给定的委托CacheManager实例集合。允许NoOpCacheManager自动添加到列表末尾，以便在没有后备存储的情况下处理缓存声明。否则，任何自定义CacheManager也可以扮演最后一个委托的角色，懒惰地为任何请求的名称创建缓存区域。注意：如果复合管理器委托的常规CacheManagers需要从getCache（String）返回null，如果它们不知道指定的缓存名称，则允许迭代到下一个委托。但是，大多数CacheManager实现都会在请求时回退到命名缓存的延迟创建;查看具有固定缓存名称的“静态”模式的特定配置详细信息（如果有）。

　　通过CompositeCacheManager 可以配置过个CacheManager，每个CacheManager可以配置不同的序列化器。

public class CompositeCacheManager implements CacheManager, InitializingBean {private final List<CacheManager> cacheManagers = new ArrayList<CacheManager>();private boolean fallbackToNoOpCache = false;/*** Construct an empty CompositeCacheManager, with delegate CacheManagers to* be added via the {@link #setCacheManagers "cacheManagers"} property.*/public CompositeCacheManager() {}/*** Construct a CompositeCacheManager from the given delegate CacheManagers.* @param cacheManagers the CacheManagers to delegate to*/public CompositeCacheManager(CacheManager... cacheManagers) {setCacheManagers(Arrays.asList(cacheManagers));}/*** Specify the CacheManagers to delegate to.*/public void setCacheManagers(Collection<CacheManager> cacheManagers) {this.cacheManagers.addAll(cacheManagers);}/*** Indicate whether a {@link NoOpCacheManager} should be added at the end of the delegate list.* In this case, any {@code getCache} requests not handled by the configured CacheManagers will* be automatically handled by the {@link NoOpCacheManager} (and hence never return {@code null}).*/public void setFallbackToNoOpCache(boolean fallbackToNoOpCache) {this.fallbackToNoOpCache = fallbackToNoOpCache;}@Overridepublic void afterPropertiesSet() {if (this.fallbackToNoOpCache) {this.cacheManagers.add(new NoOpCacheManager());}}@Overridepublic Cache getCache(String name) {for (CacheManager cacheManager : this.cacheManagers) {Cache cache = cacheManager.getCache(name);if (cache != null) {return cache;}}return null;}@Overridepublic Collection<String> getCacheNames() {Set<String> names = new LinkedHashSet<String>();for (CacheManager manager : this.cacheManagers) {names.addAll(manager.getCacheNames());}return Collections.unmodifiableSet(names);}}

转载于:https://www.cnblogs.com/hujunzheng/p/10084452.html