Flutter web cache

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Flutter Web Cache

When building web applications with Flutter, caching can be useful in order to improve performance and reduce load times. There are different options available for caching data in Flutter web applications.

1. Browser Caching

By default, web browsers cache assets like CSS files, JavaScript files, and images to avoid unnecessary network requests. This caching mechanism is automatically handled by the browser and Flutter has no control over it. However, you can control caching behavior to some extent using appropriate HTTP headers.

2. Memory Caching

Flutter provides a memory cache through the `MemoryImage` class that can be used to cache images. The `MemoryImage` class allows you to load an image once and retain it in memory for faster access later on. Here’s an example:

    
import 'package:flutter/material.dart';

MemoryImage cachedImage;

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    if (cachedImage == null) {
      cachedImage = MemoryImage(NetworkImage('https://example.com/image.jpg'));
    }

    return Image(
      image: cachedImage,
      fit: BoxFit.cover,
    );
  }
}

3. Data Caching

If you need to cache data fetched from an API or some other source, you can use plugins like `hive`, `sembast`, or `shared_preferences` to store and retrieve data locally. These plugins provide key-value stores or more advanced database-like functionality to cache and query data. Here’s an example using `shared_preferences`:

    
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: SharedPreferences.getInstance(),
      builder: (context, snapshot) {
        if (snapshot.hasData) {
          final prefs = snapshot.data;
          final cachedData = prefs.getString('cached_data');

          if (cachedData != null) {
            // Data is cached, use it
            return Text('Cached Data: $cachedData');
          } else {
            // Fetch data and cache it
            fetchDataFromApi().then((data) {
              prefs.setString('cached_data', data);
            });

            return Text('Fetching Data...');
          }
        } else {
          return Text('Loading...');
        }
      },
    );
  }

  Future fetchDataFromApi() async {
    // Simulate API call delay
    await Future.delayed(Duration(seconds: 2));
    return 'Some API data';
  }
}

These are just a few examples of caching techniques that can be used in Flutter web applications. The choice of caching mechanism depends on the specific requirements of your application.

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