在上一篇中springboot 2.X 集成redis中提到了在spring-boot-starter-data-redis中使用JdkSerializationRedisSerializerl来实现序列化，
这里看下具体是如何实现的。
1.RedisSerializer接口
在spring-data-redis包下，有一个RedisSerializer接口，提供了序列化和反序列化的基本接口。
public interface RedisSerializer<T> {
/**
* Serialize the given object to binary data.
*
* @param t object to serialize. Can be {@literal null}.
* @return the equivalent binary data. Can be {@literal null}.
*/
@Nullable
byte[] serialize(@Nullable T t) throws SerializationException;
/**
* Deserialize an object from the given binary data.
*
* @param bytes object binary representation. Can be {@literal null}.
* @return the equivalent object instance. Can be {@literal null}.
*/
@Nullable
T deserialize(@Nullable byte[] bytes) throws SerializationException;
/**
* Obtain a {@link RedisSerializer} using java serialization.<br />
* <strong>Note:</strong> Ensure that your domain objects are actually {@link java.io.Serializable serializable}.
*
* @return never {@literal null}.
* @since 2.1
*/
static RedisSerializer<Object> java() {
return java(null);
}
/**
* Obtain a {@link RedisSerializer} using java serialization with the given {@link ClassLoader}.<br />
* <strong>Note:</strong> Ensure that your domain objects are actually {@link java.io.Serializable serializable}.
*
* @param classLoader the {@link ClassLoader} to use for deserialization. Can be {@literal null}.
* @return new instance of {@link RedisSerializer}. Never {@literal null}.
* @since 2.1
*/
static RedisSerializer<Object> java(@Nullable ClassLoader classLoader) {
return new JdkSerializationRedisSerializer(classLoader);
}
/**
* Obtain a {@link RedisSerializer} that can read and write JSON using
* <a href="http://github.com/FasterXML/jackson-core">Jackson</a>.
*
* @return never {@literal null}.
* @since 2.1
*/
static RedisSerializer<Object> json() {
return new GenericJackson2JsonRedisSerializer();
}
/**
* Obtain a simple {@link java.lang.String} to {@literal byte[]} (and back) serializer using
* {@link java.nio.charset.StandardCharsets#UTF_8 UTF-8} as the default {@link java.nio.charset.Charset}.
*
* @return never {@literal null}.
* @since 2.1
*/
static RedisSerializer<String> string() {
return StringRedisSerializer.UTF_8;
}
}
可以看到byte[] serialize(@Nullable T t)和T deserialize(@Nullable byte[] bytes)就是序列化和反序列化接口，并且下面还定义了java的JdkSerializationRedisSerializer序列化、json的GenericJackson2JsonRedisSerializer和string的StringRedisSerializer.UTF_8.
2.1 JdkSerializationRedisSerializer序列化
public class JdkSerializationRedisSerializer implements RedisSerializer<Object> {
private final Converter<Object, byte[]> serializer;
private final Converter<byte[], Object> deserializer;
/**
* Creates a new {@link JdkSerializationRedisSerializer} using the default class loader.
*/
public JdkSerializationRedisSerializer() {
this(new SerializingConverter(), new DeserializingConverter());
}
/**
* Creates a new {@link JdkSerializationRedisSerializer} using a {@link ClassLoader}.
*
* @param classLoader the {@link ClassLoader} to use for deserialization. Can be {@literal null}.
* @since 1.7
*/
public JdkSerializationRedisSerializer(@Nullable ClassLoader classLoader) {
this(new SerializingConverter(), new DeserializingConverter(classLoader));
}
/**
* Creates a new {@link JdkSerializationRedisSerializer} using a {@link Converter converters} to serialize and
* deserialize objects.
*
* @param serializer must not be {@literal null}
* @param deserializer must not be {@literal null}
* @since 1.7
*/
public JdkSerializationRedisSerializer(Converter<Object, byte[]> serializer, Converter<byte[], Object> deserializer) {
Assert.notNull(serializer, "Serializer must not be null!");
Assert.notNull(deserializer, "Deserializer must not be null!");
this.serializer = serializer;
this.deserializer = deserializer;
}
public Object deserialize(@Nullable byte[] bytes) {
if (SerializationUtils.isEmpty(bytes)) {
return null;
}
try {
return deserializer.convert(bytes);
} catch (Exception ex) {
throw new SerializationException("Cannot deserialize", ex);
}
}
@Override
public byte[] serialize(@Nullable Object object) {
if (object == null) {
return SerializationUtils.EMPTY_ARRAY;
}
try {
return serializer.convert(object);
} catch (Exception ex) {
throw new SerializationException("Cannot serialize", ex);
}
}
}
在JdkSerializationRedisSerializer构造方法中，传入了Converter的两个对象，serialize的序列化就使用SerializingConverter的convert方法
public byte[] convert(Object source) {
try {
return this.serializer.serializeToByteArray(source);
}
catch (Throwable ex) {
throw new SerializationFailedException("Failed to serialize object using " +
this.serializer.getClass().getSimpleName(), ex);
}
}
