如何正确实现Page接口分页，用PageImpl 自定义分页

/**
 * Constructor of {@code PageImpl}.
 * 
 * @param content the content of this page, must not be {@literal null}.
 * @param pageable the paging information, must not be {@literal null}.
 * @param total the total amount of items available. The total might be adapted considering the length of the content
 * given, if it is going to be the content of the last page. This is in place to mitigate inconsistencies.
 */
public PageImpl(List<T> content, Pageable pageable, long total)

content：当前页的记录。
total：所有记录数
也就是用PageImpl实现Page接口的时候，不能把数据全取回来放入content，得按分页的size放入。而最后一个参数需要记录的是所有数据的计数。

    public Page<ESIndexObject> getAllESIndex(Pageable pageable) {
        String strQuery = "/_cat/indices?v&h=uuid,health,status,index,docsCount,storeSize,cds&s=cds:desc&format=json";
        Request request = new Request("GET", strQuery);
        try {
            Response response = restClient.performRequest(request);
            String responseBody = EntityUtils.toString(response.getEntity());
            ObjectMapper mapper = new ObjectMapper();
　　　　　　
            List<ESIndexObject> list = mapper.readValue(responseBody,new TypeReference<List<ESIndexObject>>(){});
            int totalElements = list.size();
            if(pageable==null)
            {
                pageable = PageRequest.of(0,10);
            }
            int fromIndex = pageable.getPageSize()*pageable.getPageNumber();
            int toIndex = pageable.getPageSize()*(pageable.getPageNumber()+1);
            if(toIndex>totalElements) toIndex = totalElements;

　　　　　　　//如果list的内容取回后基本不变化，可以考虑放入类对象变量里或者其他缓存里，然后判断list是否可用，不用每次都去取list，适合取数的时候无法真分页只能伪分页情况。
            //类似取mysql数据库的情况，因为数据取数本身支持分页，所以list的数据每次都取当前页就可以，但是需要先要计算所有记录数，然后传入totalElements变量
            List<ESIndexObject> indexObjects = list.subList(fromIndex,toIndex);#获取当前页数据
            Page<ESIndexObject> page = new PageImpl<>(indexObjects,pageable,totalElements);
            return page;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }