REST Pagination in Spring – Spring中的REST分页

最后修改: 2012年 1月 18日


1. Overview


This tutorial will focus on the implementation of pagination in a REST API using Spring MVC and Spring Data.

本教程将重点介绍使用Spring MVC和Spring Data在REST API中实现分页。

2. Page as Resource vs Page as Representation


The first question when designing pagination in the context of a RESTful architecture is whether to consider the page an actual Resource or just a Representation of Resources.


Treating the page itself as a resource introduces a host of problems, such as no longer being able to uniquely identify resources between calls. This, coupled with the fact that, in the persistence layer, the page isn’t a proper entity but a holder that’s constructed when necessary, makes the choice straightforward; the page is part of the representation.


The next question in the pagination design in the context of REST is where to include the paging information:


  • in the URI path: /foo/page/1
  • the URI query: /foo?page=1

Keeping in mind that a page isn’t a Resource, encoding the page information in the URI isn’t an option.


We’ll use the standard way of solving this problem by encoding the paging information in a URI query.


3. The Controller


Now for the implementation. The Spring MVC Controller for pagination is straightforward:

现在说说实现。用于分页的Spring MVC控制器是直接的

@GetMapping(params = { "page", "size" })
public List<Foo> findPaginated(@RequestParam("page") int page, 
  @RequestParam("size") int size, UriComponentsBuilder uriBuilder,
  HttpServletResponse response) {
    Page<Foo> resultPage = service.findPaginated(page, size);
    if (page > resultPage.getTotalPages()) {
        throw new MyResourceNotFoundException();
    eventPublisher.publishEvent(new PaginatedResultsRetrievedEvent<Foo>(
      Foo.class, uriBuilder, response, page, resultPage.getTotalPages(), size));

    return resultPage.getContent();

In this example, we’re injecting the two query parameters, size and page, in the Controller method via @RequestParam.


Alternatively, we could have used a Pageable object, which maps the pagesize, and sort parameters automatically. In addition, the PagingAndSortingRepository entity provides out-of-the-box methods that support using Pageable as a parameter.


We’re also injecting the Http Response and the UriComponentsBuilder to help with Discoverability, which we’re decoupling via a custom event. If that’s not a goal of the API, we can simply remove the custom event.

我们还注入了Http Response和UriComponentsBuilder以帮助实现可发现性,我们通过一个自定义事件将其解耦。如果这不是API的目标,我们可以简单地删除这个自定义事件。

Finally, note that the focus of this article is only the REST and web layer; to go deeper into the data access part of pagination, we can check out this article about Pagination with Spring Data.

最后,请注意,本文的重点只是REST和Web层;要深入了解分页的数据访问部分,我们可以查看这篇关于Spring Data分页的文章

4. Discoverability for REST Pagination


Within the scope of pagination, satisfying the HATEOAS constraint of REST means enabling the client of the API to discover the next and previous pages based on the current page in the navigation. For this purpose, we’ll use the Link HTTP header, coupled with the “next,” “prev,” “first,” and “last” link relation types.

在分页的范围内,满足REST的HATEOAS约束意味着使API的客户端能够根据导航中的当前页面发现下一个前一个页面。为此,我们将使用Link HTTP头,再加上”next,” “prev,” “first,” 和 “last” 链接关系类型

In REST, Discoverability is a cross-cutting concern, applicable not only to specific operations, but to types of operations. For example, each time a Resource is created, the URI of that Resource should be discoverable by the client. Since this requirement is relevant for the creation of ANY Resource, we’ll handle it separately.


We’ll decouple these concerns using events, as we discussed in the previous article focusing on Discoverability of a REST Service. In the case of pagination, the event, PaginatedResultsRetrievedEvent, is fired in the controller layer. Then we’ll implement discoverability with a custom listener for this event.


In short, the listener will check if the navigation allows for nextpreviousfirst and last pages. If it does, it’ll add the relevant URIs to the response as a ‘Link’ HTTP Header.

简而言之,监听器将检查导航是否允许nextpreviousfirstlast页。如果允许,它将将相关的URI作为 “链接 “HTTP头添加到响应中

Now let’s go step by step. The UriComponentsBuilder passed from the controller contains only the base URL (the host, the port and the context path). Therefore, we’ll have to add the remaining sections:


void addLinkHeaderOnPagedResourceRetrieval(
 UriComponentsBuilder uriBuilder, HttpServletResponse response,
 Class clazz, int page, int totalPages, int size ){

   String resourceName = clazz.getSimpleName().toString().toLowerCase();
   uriBuilder.path( "/admin/" + resourceName );

    // ...

Next, we’ll use a StringJoiner to concatenate each link. We’ll use the uriBuilder to generate the URIs. Let’s see how we proceed with the link to the next page:


StringJoiner linkHeader = new StringJoiner(", ");
if (hasNextPage(page, totalPages)){
    String uriForNextPage = constructNextPageUri(uriBuilder, page, size);
    linkHeader.add(createLinkHeader(uriForNextPage, "next"));

Let’s have a look at the logic of the constructNextPageUri method:


String constructNextPageUri(UriComponentsBuilder uriBuilder, int page, int size) {
    return uriBuilder.replaceQueryParam(PAGE, page + 1)
      .replaceQueryParam("size", size)

We’ll proceed similarly for the rest of the URIs that we want to include.


Finally, we’ll add the output as a response header:


response.addHeader("Link", linkHeader.toString());

Note that, for brevity, only a partial code sample is included, and the full code is here.


5. Test Driving Pagination


Both the main logic of pagination and discoverability are covered by small, focused integration tests. As in the previous article, we’ll use the REST-assured library to consume the REST service and verify the results.

分页和可发现性的主要逻辑都由小型的、集中的集成测试来覆盖。正如上一篇文章,我们将使用REST-assured 库来消费REST服务并验证结果。

These are a few examples of pagination integration tests; for a full test suite, check out the GitHub project (link at the end of the article):


public void whenResourcesAreRetrievedPaged_then200IsReceived(){
    Response response = RestAssured.get(paths.getFooURL() + "?page=0&size=2");

    assertThat(response.getStatusCode(), is(200));
public void whenPageOfResourcesAreRetrievedOutOfBounds_then404IsReceived(){
    String url = getFooURL() + "?page=" + randomNumeric(5) + "&size=2";
    Response response = RestAssured.get.get(url);

    assertThat(response.getStatusCode(), is(404));
public void givenResourcesExist_whenFirstPageIsRetrieved_thenPageContainsResources(){
   Response response = RestAssured.get(paths.getFooURL() + "?page=0&size=2");


6. Test Driving Pagination Discoverability


Testing that pagination is discoverable by a client is relatively straightforward, although there’s a lot of ground to cover.


The tests will focus on the position of the current page in navigation, and the different URIs that should be discoverable from each position:


public void whenFirstPageOfResourcesAreRetrieved_thenSecondPageIsNext(){
   Response response = RestAssured.get(getFooURL()+"?page=0&size=2");

   String uriToNextPage = extractURIByRel(response.getHeader("Link"), "next");
   assertEquals(getFooURL()+"?page=1&size=2", uriToNextPage);
public void whenFirstPageOfResourcesAreRetrieved_thenNoPreviousPage(){
   Response response = RestAssured.get(getFooURL()+"?page=0&size=2");

   String uriToPrevPage = extractURIByRel(response.getHeader("Link"), "prev");
   assertNull(uriToPrevPage );
public void whenSecondPageOfResourcesAreRetrieved_thenFirstPageIsPrevious(){
   Response response = RestAssured.get(getFooURL()+"?page=1&size=2");

   String uriToPrevPage = extractURIByRel(response.getHeader("Link"), "prev");
   assertEquals(getFooURL()+"?page=0&size=2", uriToPrevPage);
public void whenLastPageOfResourcesIsRetrieved_thenNoNextPageIsDiscoverable(){
   Response first = RestAssured.get(getFooURL()+"?page=0&size=2");
   String uriToLastPage = extractURIByRel(first.getHeader("Link"), "last");

   Response response = RestAssured.get(uriToLastPage);

   String uriToNextPage = extractURIByRel(response.getHeader("Link"), "next");

Note that the full low-level code for extractURIByRel, responsible for extracting the URIs by rel relation, is here.


7. Getting All Resources


On the same topic of pagination and discoverability, the choice must be made if a client is allowed to retrieve all the Resources in the system at once, or if the client must ask for them paginated.


If it’s decided that the client can’t retrieve all Resources with a single request, and pagination is required, then several options are available for the response to get a request. One option is to return a 404 (Not Found) and use the Link header to make the first page discoverable:

如果决定客户端不能用一个请求来检索所有的资源,并且需要分页,那么对于得到一个请求的响应有几种选择。一种选择是返回404(Not Found),并使用Link头来使第一页可被发现。

Link=<http://localhost:8080/rest/api/admin/foo?page=0&size=2>; rel=”first”, <http://localhost:8080/rest/api/admin/foo?page=103&size=2>; rel=”last”

Link=<http://localhost:8080/rest/api/admin/foo?page=0&size=2>; rel=”第一”, <http://localhost:8080/rest/api/admin/foo?page=103&size=2>; rel=”最后”

Another option is to return a redirect, 303 (See Other), to the first page. A more conservative route would be to simply return to the client a 405 (Method Not Allowed) for the GET request.

另一个选择是返回一个重定向,303 (See Other),到第一个页面。一个更保守的方法是简单地给客户返回一个405(不允许的方法)的GET请求。

8. REST Paging With Range HTTP Headers

8.使用Range HTTP头的REST分页

A relatively different way of implementing pagination is to work with the HTTP Range headers, Range, Content-Range, If-Range, Accept-Ranges, and HTTP status codes, 206 (Partial Content), 413 (Request Entity Too Large), and 416 (Requested Range Not Satisfiable).

实现分页的一个相对不同的方法是使用HTTP Range头信息, Range, Content-Range, If-Range,Accept-Ranges,HTTP状态代码,206(部分内容),413(Request Entity Too Large)和416(Requested Range Not Satisfiable)。

One view of this approach is that the HTTP Range extensions aren’t intended for pagination, and they should be managed by the Server, not by the Application. Implementing pagination based on the HTTP Range header extensions is technically possible, although not nearly as common as the implementation discussed in this article.


9. Spring Data REST Pagination

9.Spring Data REST Pagination

In Spring Data, if we need to return a few results from the complete data set, we can use any Pageable repository method, as it will always return a Page. The results will be returned based on the page number, page size, and sorting direction.

在Spring Data中,如果我们需要从完整的数据集中返回一些结果,我们可以使用任何Pageable存储库方法,因为它总是会返回一个Page.结果将根据页数、页面大小和排序方向返回。

Spring Data REST automatically recognizes URL parameters like page, size, sort etc.

Spring Data REST自动识别URL参数,如page, size, sort

To use paging methods of any repository, we need to extend PagingAndSortingRepository:


public interface SubjectRepository extends PagingAndSortingRepository<Subject, Long>{}

If we call http://localhost:8080/subjects, Spring automatically adds the page, size, sort parameter suggestions with the API:


"_links" : {
  "self" : {
    "href" : "http://localhost:8080/subjects{?page,size,sort}",
    "templated" : true

By default, the page size is 20, but we can change it by calling something like http://localhost:8080/subjects?page=10.


If we want to implement paging into our own custom repository API, we need to pass an additional Pageable parameter and make sure that API returns a Page:


@RestResource(path = "nameContains")
public Page<Subject> findByNameContaining(@Param("name") String name, Pageable p);

Whenever we add a custom API, a /search endpoint gets added to the generated links. So if we call http://localhost:8080/subjects/search, we’ll see a pagination capable endpoint:


"findByNameContaining" : {
  "href" : "http://localhost:8080/subjects/search/nameContains{?name,page,size,sort}",
  "templated" : true

All APIs that implement PagingAndSortingRepository will return a Page. If we need to return the list of the results from the Page, the getContent() API of Page provides the list of records fetched as a result of the Spring Data REST API.

所有实现PagingAndSortingRepository的API都将返回一个Page。如果我们需要返回Page的结果列表,Page的getContent()API提供了作为Spring Data REST API结果获取的记录列表。

10. Convert a List into a Page


Let’s suppose that we have a Pageable object as input, but the information that we need to retrieve is contained in a list instead of a PagingAndSortingRepository. In these cases, we may need to convert a List into a Page.


For example, imagine that we have a list of results from a SOAP service:


List<Foo> list = getListOfFooFromSoapService();

We need to access the list in the specific positions specified by the Pageable object sent to us. So let’s define the start index:


int start = (int) pageable.getOffset();

And the end index:


int end = (int) ((start + pageable.getPageSize()) > fooList.size() ? fooList.size()
  : (start + pageable.getPageSize()));

Having these two in place, we can create a Page to obtain the list of elements between them:


Page<Foo> page 
  = new PageImpl<Foo>(fooList.subList(start, end), pageable, fooList.size());

That’s it! We can now return page as a valid result.


And note that if we also want to give support for sorting, we need to sort the list before sub-listing it.


11. Conclusion


This article illustrated how to implement Pagination in a REST API using Spring, and discussed how to set up and test Discoverability.

这篇文章说明了如何使用Spring在REST API中实现分页,并讨论了如何设置和测试可发现性。

If we want to go in depth on pagination in the persistence level, we can check out the JPA or Hibernate pagination tutorials.


The implementation of all these examples and code snippets can be found in the GitHub project – this is a Maven-based project, so it should be easy to import and run as it is.