当用户在app中滚动时，从服务器发送JSON

Question

I am making a wallpaper app for android. And also building API on my private server for it. My problem is what should be done on the server side so that only those image's JSON is sent which are required. That is, on the app screen, if 10 grids are available then only 10 images are fetched and rest gets loaded when the user scrolls.

Answer 1

You can pass an additional parameter like page={{pageNumber}} and handle it in server side.

For example if your api is example.com/api, then by default you should assume it contains page=0. You should choose a threshold of data per page. For example if you choose your threshold as 10, then the above api call should return first 10 images.

In the app, you should listen to the scroll event and if the last visible item reached the end of data you are having, then call the api with page={{lastPageNumber+1}} and you should handle it in server side to return corresponding data for that page numbers.

This is a rough implementation of what would be like in server side if you use mysql and php.

<?php
$page = 0;
if (isset($_GET['page'])) {
    $page=$_GET['page'];
}

$threshold = 10;
$offset = $threshold + ($threshold * $page);

mysql_connect("domain", "username", "password")
            or die('Could not connect: ' . mysql_error());
    mysql_select_db("dbName") or die('Could not select database');


$sql=" SELECT COLUMN_NAMES from TABLE_NAME limit $threshold offset $offset";

 $result = mysql_query($sql) or die('Query failed: ' . mysql_error());

 //process the $result
?>