redis在缓存POJO的时候需要将POJO序列化为byte数组进行存储，spring-data-redis实现了类JdkSerializationRedisSerializer对POJO进行序列化。类图结构如上，主要流程如下：
1.JdkSerializationRedisSerializer类实现接口RedisSerializer类中
byte[] serialize(T t)和T deserialize(byte[] bytes)接口。
2.通过定义SerializingConverter和DeserializingConverter对象，对POJO进行序列化和反序列化。
public JdkSerializationRedisSerializer() {
this(new SerializingConverter(), new DeserializingConverter());
}
3.对于SerializingConverter，通过定义DefaultSerializer对象并调用serialize(Object object, OutputStream outputStream)方法，对POJO进行序列化操作。
public SerializingConverter() {
this.serializer = new DefaultSerializer();
}
@Override
public byte[] convert(Object source) {
ByteArrayOutputStream byteStream = new ByteArrayOutputStream(1024);
try {
this.serializer.serialize(source, byteStream);
return byteStream.toByteArray();
}
catch (Throwable ex) {
throw new SerializationFailedException("Failed to serialize object using " +
this.serializer.getClass().getSimpleName(), ex);
}
}
public class DefaultSerializer implements Serializer<Object> {
@Override
public void serialize(Object object, OutputStream outputStream) throws IOException {
if (!(object instanceof Serializable)) {
throw new IllegalArgumentException(getClass().getSimpleName() + " requires a Serializable payload " +
"but received an object of type [" + object.getClass().getName() + "]");
}
ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
objectOutputStream.writeObject(object);
objectOutputStream.flush();
}
}
4.对于DeserializingConverter，通过定义DefaultDeserializer对象并调用deserialize(InputStream inputStream)方法对POJO进行反序列化。
public DeserializingConverter() {
this.deserializer = new DefaultDeserializer();
}
@Override
public Object convert(byte[] source) {
ByteArrayInputStream byteStream = new ByteArrayInputStream(source);
try {
return this.deserializer.deserialize(byteStream);
}
catch (Throwable ex) {
throw new SerializationFailedException("Failed to deserialize payload. " +
"Is the byte array a result of corresponding serialization for " +
this.deserializer.getClass().getSimpleName() + "?", ex);
}
}
public class DefaultDeserializer implements Deserializer<Object> {
private final ClassLoader classLoader;
@Override
@SuppressWarnings("resource")
public Object deserialize(InputStream inputStream) throws IOException {
ObjectInputStream objectInputStream = new ConfigurableObjectInputStream(inputStream, this.classLoader);
try {
return objectInputStream.readObject();
}
catch (ClassNotFoundException ex) {
throw new NestedIOException("Failed to deserialize object type", ex);
}
}
}
5.底层还是通过调用JDK的IO操作ObjectInputStream和ObjectOutputStream类实现POJO的序列化和反序列化。