使用 Laravel API 进行滚动分页

Question

我在 Android 中使用带有分页数据的 Laravel API...

我想获取自动分页数据。 例如第一页上的数据首先加载，当我向下滚动时，下一页继续加载！

Answer 1

在 Laravel 方面

// Get Collection
$query = SomeModel::where('some_thing', "5")
->paginate(10);

return Response::json(array(
            'some_result' => $query,
        ));

在 Android 端（改造调用）

@FormUrlEncoded
@POST
Call<JsonObject> getActions(
        @Url String url);

在 Android 端（活动/片段）

public class NewTemplateActivity
        extends AppCompatActivity {

    // Recycler View
    private SomeActionListAdapter someActionsAdapter;
    private List<SomesomeActionListModel> listSomeActionModel;
    private RecyclerView rv;

    private Boolean isScrolling = false;
    private int currentItems, totalItems, scrollOutItems;
    private int pageNumber = 1;
    private Boolean firstLoad = true;
    private Boolean firstSearch = false;
    private LinearLayoutManager manager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list);

        // Init Recycler View
        rv = findViewById(R.id.f_list_rv_list);
        rv.setHasFixedSize(true);
        listSomeActionModel = new ArrayList<>();
        someActionsAdapter = new SomeActionListAdapter(
                mContext,
                listSomeActionModel);

        manager = new LinearLayoutManager(mContext);
        rv.setLayoutManager(manager);
        rv.setAdapter(someActionsAdapter);
    }

    private void getSomeAction(
            String url) {

        if (firstLoad || firstSearch) {
            listSomeActionModel.clear();
        }

        // Retrofit Call
        Call<JsonObject> call = RetrofitClientLaravel.getInstance(mContext)
                                                     .discussGetApi()
                                                     .getSomeAction(url);

        call.enqueue(new Callback<JsonObject>() {

            @Override
            public void onResponse(
                    Call<JsonObject> call,
                    Response<JsonObject> response) {

                JSONObject jsonObject;
                try {
                    jsonObject = new JSONObject(new Gson().toJson(response.body()));

                    // Get The Relevant Array
                    JSONObject jsonObject2 = jsonObject.getJSONObject("some_result");
                    JSONArray returnArray = jsonObject2.getJSONArray("data");

                    onScrolled();

                    if (!returnArray.isNull(0)) {

                        for (int l = 0; l < returnArray.length(); l++) {
                            if (returnArray.length() > 0) {

                                // Get The Json Object
                                JSONObject returnJSONObject = returnArray.getJSONObject(l);

                                // Get Details
                                String id = returnJSONObject.optString("SomesomeAction_id");

                                // Populate The Array List
                                listSomeActionModel.add(new SomesomeActionListModel(id));
                            }
                        }
                    }

                    if (firstLoad || firstSearch) {

                        someActionsAdapter = new SomeActionListAdapter(
                                mContext,
                                listSomeActionModel);
                        rv.setAdapter(someActionsAdapter);
                    }

                    someActionsAdapter.notifyDataSetChanged();
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onFailure(
                    Call<JsonObject> call,
                    Throwable t) {

            }
        });
    }

    public void onScrolled() {

        rv.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(
                    RecyclerView recyclerView,
                    int newState) {
                super.onScrollStateChanged(
                        recyclerView,
                        newState);
                if (newState == AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
                    isScrolling = true;
                }
            }

            @Override
            public void onScrolled(
                    RecyclerView recyclerView,
                    int dx,
                    int dy) {
                super.onScrolled(
                        recyclerView,
                        dx,
                        dy);

                currentItems = manager.getChildCount();
                totalItems = manager.getItemCount();
                scrollOutItems = manager.findFirstVisibleItemPosition();

                if (isScrolling && (currentItems + scrollOutItems == totalItems)) {
                    isScrolling = false;
                    firstLoad = false;
                    firstSearch = false;

                    Toast.makeText(
                            mContext,
                            "Loading More...",
                            Toast.LENGTH_SHORT)
                         .show();

                    pageNumber++;

                    getSomeAction(Env.LARAVEL_MAIN_URL +
                                  "/api/get_SomesomeActions" +
                                  "?page=" +
                                  pageNumber);
                }
            }
        });
    }
}

Answer 2

您可以使用 LengthAwarePaginator 轻松做到这一点

protected function paginate(Collection $collection)
{
    $rules = [
        'per_page' => 'integer|min:2|max:50',
    ];

    Validator::validate(request()->all(), $rules);

    $page = LengthAwarePaginator::resolveCurrentPage();

    $perPage = 15;
    if (request()->has('per_page')) {
        $perPage = (int) request()->per_page;
    }

    $results = $collection->slice(($page - 1) * $perPage, $perPage)->values();

    $paginated = new LengthAwarePaginator($results, $collection->count(), $perPage, $page, [
        'path' => LengthAwarePaginator::resolveCurrentPath(),
    ]);

    $paginated->appends(request()->all());

    return $paginated;

}

确保导入所有需要的命名空间， 您可以继续对集合进行分页

$collection = $this->paginate($collection);

希望对你有帮助

Answer 3

你可以在获取行的状态下使用 laravel 默认的分页方法。

例如我想显示用户列表：

//状态：

$users = User::get();

//使用：

$users = User::paginate();

更多信息：laravel 网站 https://laravel.com/docs/5.5/pagination