区别？和T在我的设计中扩展了SomeClass

Question

我以两种不同的方式为我的课程建模：一个使用？而另一个使用T扩展了SomeClass。我想知道哪种方法是正确的方法。 基本上我有一个对象，我想将它保留在我的数据存储区中。从客户端我刚收到一个客户，我向该对象添加一些metaDataInfo，然后选择该对象的Id /密钥，然后使用密钥和对象将其保留。我想确保我持久化的对象有metaInfo而不仅仅是任何对象。

使用T的Option1扩展了SomeClass：

public class Client {

public static void main(String[] args) {
    Customer customer = new Customer();
    Persister.save(customer);
}

static class Persister {
    static void save(Customer customer) {
        EntityWithMetaDataImpl<Customer> entityWithMetaData = new EntityWithMetaDataImpl<>("metadata", customer);
        String key = "key";
        PersistentEntity<EntityWithMetaDataImpl<Customer>> impl = new PersistentEntity<>(key, entityWithMetaData);
        ActualPersister.save(impl);
    }
}

static class ActualPersister {
    static <T extends EntityWithMetaData> void save(PersistentEntity<T> entity) {
        // save record with entity.getObjectKey() and
        // entity.getActualObject();
    }
}
}

public class Customer {
  String name;
  public String getName() { return name;}
  public void setName(String name) { this.name = name; }
}

public interface EntityWithMetaData {   
  public String getMetaData();
}

public class EntityWithMetaDataImpl<T> implements EntityWithMetaData {
  private T actualObject;
  private String metaData;

  EntityWithMetaDataImpl(String metaData, T actualObject) {
    this.metaData = metaData;
    this.actualObject = actualObject;
  }

public T getActualObject() {
    return actualObject;
}

@Override
public String getMetaData() {
    return metaData;
}
}

public class PersistentEntity<T extends EntityWithMetaData> {
String key;
T actualObject;

PersistentEntity(String key, T entity){
    this.key = key;
    this.actualObject = entity;
}

public String getObjectKey() { return key;}

public T getActualObject() { return actualObject; }

}

Option2使用？：

public class Client {

public static void main(String[] args) {
    Customer customer = new Customer();
    Persister.save(customer);
}

static class Persister {
    static void save(Customer customer) {
        EntityWithMetaData<Customer> entityWithMetaData = new EntityWithMetaData<>("metadata", customer);
        String key = "key";
        PersistentEntity impl = new PersistentEntity(key, entityWithMetaData);
        ActualPersister.save(impl);
    }
}

static class ActualPersister {
    static void save(PersistentEntity persisterEntity) {
        // save record with persisterEntity.getObjectKey() and
        // persisterEntity.getActualObject();
    }
}
}
public class EntityWithMetaData<T>{

private T actualObject;
private String metaData;

EntityWithMetaData(String metaData, T actualObject) {
    this.metaData = metaData;
    this.actualObject = actualObject;
}

public T getActualObject() {
    return actualObject;
}

public String getMetaData() {
    return metaData;
}

}

public class PersistentEntity {

String key;
EntityWithMetaData<?> actualObject;

PersistentEntity(String key, EntityWithMetaData<?> entity){
    this.key = key;
    this.actualObject = entity;
}

public String getObjectKey() {
    return key;
}

public EntityWithMetaData<?> getActualObject() {
    return actualObject;
}
}