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;
    }

    @Override
    public 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;
    }

    @Override
    public 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;
    }

    @Override
    public 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;
    }

    @Override
    public 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()))
                );
    }

    @Override
    public 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 {

    @Override
    protected 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;
    }

    @Override
    public void afterPropertiesSet() {
        if (this.fallbackToNoOpCache) {
            this.cacheManagers.add(new NoOpCacheManager());
        }
    }

    @Override
    public Cache getCache(String name) {
        for (CacheManager cacheManager : this.cacheManagers) {
            Cache cache = cacheManager.getCache(name);
            if (cache != null) {
                return cache;
            }
        }
        return null;
    }

    @Override
    public Collection<String> getCacheNames() {
        Set<String> names = new LinkedHashSet<String>();
        for (CacheManager manager : this.cacheManagers) {
            names.addAll(manager.getCacheNames());
        }
        return Collections.unmodifiableSet(names);
    }

}