什么<s extends =“”t =“”> List <s> save（Iterable <s> entities）意味着

Question

它位于JpaRepository

    /*
 * Copyright 2008-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
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package org.springframework.data.jpa.repository;

import java.io.Serializable;
import java.util.List;

import javax.persistence.EntityManager;

import org.springframework.data.domain.Example;
import org.springframework.data.domain.Sort;
import org.springframework.data.repository.NoRepositoryBean;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.repository.query.QueryByExampleExecutor;

/**
 * JPA specific extension of {@link org.springframework.data.repository.Repository}.
 *
 * @author Oliver Gierke
 * @author Christoph Strobl
 * @author Mark Paluch
 */
@NoRepositoryBean
public interface JpaRepository<T, ID extends Serializable>
        extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.CrudRepository#findAll()
     */
    List<T> findAll();

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.PagingAndSortingRepository#findAll(org.springframework.data.domain.Sort)
     */
    List<T> findAll(Sort sort);

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.CrudRepository#findAll(java.lang.Iterable)
     */
    List<T> findAll(Iterable<ID> ids);

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.CrudRepository#save(java.lang.Iterable)
     */
    <S extends T> List<S> save(Iterable<S> entities);

    /**
     * Flushes all pending changes to the database.
     */
    void flush();

    /**
     * Saves an entity and flushes changes instantly.
     * 
     * @param entity
     * @return the saved entity
     */
    <S extends T> S saveAndFlush(S entity);

    /**
     * Deletes the given entities in a batch which means it will create a single {@link Query}. Assume that we will clear
     * the {@link javax.persistence.EntityManager} after the call.
     * 
     * @param entities
     */
    void deleteInBatch(Iterable<T> entities);

    /**
     * Deletes all entities in a batch call.
     */
    void deleteAllInBatch();

    /**
     * Returns a reference to the entity with the given identifier.
     * 
     * @param id must not be {@literal null}.
     * @return a reference to the entity with the given identifier.
     * @see EntityManager#getReference(Class, Object)
     */
    T getOne(ID id);

    /* (non-Javadoc)
     * @see org.springframework.data.repository.query.QueryByExampleExecutor#findAll(org.springframework.data.domain.Example)
     */
    @Override
    <S extends T> List<S> findAll(Example<S> example);

    /* (non-Javadoc)
     * @see org.springframework.data.repository.query.QueryByExampleExecutor#findAll(org.springframework.data.domain.Example, org.springframework.data.domain.Sort)
     */
    @Override
    <S extends T> List<S> findAll(Example<S> example, Sort sort);

}

我不明白这个save ...定义是什么？在这里回答的问题What does it mean <S extends T> save (S entity); in Spring Repository?非常令人困惑，因为它的例子都使用了T而且让我更加困惑于让Dog参与....

是否有人能够逐件解释整个短语，并在需要时提供一个小例子？

基本上，用例是我扩展JpaRepository的时候。我想知道我究竟可以传递给这个.save函数，并且在这里查看这个函数定义，我不知道如何更好地理解它而不必深入研究java的更多文档和博客文章。