Need an example of HttpResponseCache in Android

HttpResponseCache in Android: A Practical Example

The HttpResponseCache class in Android provides a simple mechanism for caching HTTP responses, significantly improving the performance of network-intensive applications. In this article, we’ll walk through a concrete example of how to leverage HttpResponseCache for caching data from a weather API.

Setting Up HttpResponseCache

1. Initializing HttpResponseCache

The first step is to initialize an instance of HttpResponseCache. You can achieve this within the application’s onCreate() method.

  @Override
  public void onCreate() {
    super.onCreate();
    try {
      File httpCacheDir = new File(getCacheDir(), "http");
      long httpCacheSize = 10 * 1024 * 1024; // 10MB
      HttpResponseCache.install(httpCacheDir, httpCacheSize);
    } catch (IOException e) {
      Log.e("App", "Failed to install HTTP cache: " + e);
    }
  }

In this code:

• getCacheDir() provides the directory for application-specific cache files.
• httpCacheSize determines the maximum size of the cache.

2. Enabling HttpResponseCache

Before making any network requests, enable HttpResponseCache:

HttpResponseCache cache = HttpResponseCache.getInstalled();
if (cache != null) {
  cache.flush();
}

flush() ensures that the cache is up-to-date.

Fetching Data Using HttpResponseCache

1. Network Request with Cache

Now, when making a network request, use the HttpURLConnection class. Configure the connection to utilize the cache:

  URL url = new URL("http://api.openweathermap.org/data/2.5/weather?q=London&appid=YOUR_API_KEY");
  HttpURLConnection connection = (HttpURLConnection) url.openConnection();
  connection.setRequestProperty("Cache-Control", "max-age=60"); // Cache for 60 seconds
  
  // If cache is available, fetch data from cache.
  if (HttpResponseCache.getInstalled() != null) {
    connection.setRequestProperty("Cache-Control", "public, max-age=60"); // Cache for 60 seconds
    connection.setUseCaches(true); 
    connection.setReadTimeout(5000); // Timeout if cache is unavailable
    connection.setConnectTimeout(5000); // Timeout if connection is unavailable
    if (connection.getResponseCode() == 200) {
      // Handle data from cache
      InputStream inputStream = connection.getInputStream();
      // Process response stream
    } else {
      // Error handling 
    }
  } else {
    // Fetch data from network
    connection.setUseCaches(false);
    if (connection.getResponseCode() == 200) {
      // Handle data from network
      InputStream inputStream = connection.getInputStream();
      // Process response stream
    } else {
      // Error handling 
    }
  }

Explanation:

• Cache-Control header specifies the cache’s lifetime.
• connection.setUseCaches(true) enables the cache.
• connection.getResponseCode() checks the response code from the server.

2. Handling Cache-Hit and Cache-Miss

Based on the response code, you can differentiate between a cache-hit and a cache-miss:

if (connection.getResponseCode() == 200) {
  // Handle data from cache (or network)
} else {
  // Error handling
}

3. Disabling HttpResponseCache

To disable the cache, simply call HttpResponseCache.getInstalled().delete(). However, it’s generally recommended to keep the cache enabled for optimal performance.

HttpResponseCache.getInstalled().delete();

Advantages of HttpResponseCache

Utilizing HttpResponseCache offers several advantages:

• **Improved Performance:** Caching responses significantly reduces the time required to load data, resulting in a faster user experience.
• **Reduced Network Usage:** Fewer requests are sent to the server, conserving battery life and data usage.
• **Offline Access (Partially):** Cached data can be accessed even without an active internet connection.

Comparison Table

Conclusion

HttpResponseCache provides a convenient and effective solution for caching HTTP responses in Android applications. By implementing a simple cache mechanism, you can enhance your app’s speed, reduce network usage, and improve the overall user experience.