10 Android WebView Best Practices

Android WebView is a system component powered by Chrome that allows Android apps to display web content. WebView is often used to load HTML content, but it can also be used to load webpages, display images, and even play videos.

For developers, it’s important to understand the best practices for using WebView in order to ensure that their app is secure and performs well. In this article, we’ll discuss 10 Android WebView best practices that developers should follow.

1. Make sure to set the WebViewClient

The WebViewClient is responsible for handling the communication between the web page and the Android app. It allows you to customize how your app interacts with the web page, such as overriding URL loading, enabling JavaScript, and more. This ensures that your app behaves in a consistent manner when interacting with the web page.

Setting the WebViewClient also helps protect against malicious websites by allowing you to control which URLs are allowed to be loaded in the WebView. You can set up rules to block certain URLs or domains from being loaded, ensuring that only trusted content is displayed in your app.

2. Set JavaScript enabled

JavaScript is a scripting language used to create dynamic webpages and applications. It allows developers to add interactive elements, such as animations, forms, and other user interface components. When JavaScript is enabled in an Android WebView, it can improve the performance of the application by allowing for faster loading times and smoother transitions between pages.

Enabling JavaScript also provides access to more features that are available on the web. For example, if you want to use Google Maps or YouTube videos within your app, then enabling JavaScript will allow these services to be accessed. Additionally, some websites may require JavaScript to be enabled in order to properly display content.

To enable JavaScript in an Android WebView, you must first open the settings menu. From there, select “Advanced” and then “Enable JavaScript”. Once this setting has been enabled, all subsequent requests from the WebView will include the JavaScript code. This ensures that any website or service that requires JavaScript will be able to function correctly.

3. Disable file access within WebView

Disabling file access within WebView is a good idea because it prevents malicious code from accessing the local file system. This helps to protect user data and prevent any unauthorized access or manipulation of files stored on the device. It also reduces the risk of malware being installed on the device, as malicious code can’t access the local file system if file access is disabled.

To disable file access within WebView, developers should set the allowFileAccess attribute to false in the application’s manifest file. This will ensure that no file access is allowed within the WebView component. Additionally, developers should also set the allowUniversalAccessFromFileURLs attribute to false, which will prevent any JavaScript code from accessing the local file system.

4. Enable hardware acceleration

Hardware acceleration is a feature that allows the browser to access the device’s GPU (graphics processing unit) for faster and smoother rendering of webpages. This can be especially beneficial when displaying complex graphics or animations, as it reduces the load on the CPU and improves performance.

Enabling hardware acceleration in Android WebView is relatively simple. All you need to do is add the following line of code to your application’s manifest file: android:hardwareAccelerated=”true”. Once enabled, the browser will automatically use the GPU whenever possible.

The benefits of enabling hardware acceleration are numerous. It helps reduce battery consumption by offloading some of the work from the CPU to the GPU, which is more efficient at handling graphical tasks. Additionally, it increases the speed and responsiveness of the browser, resulting in a better user experience. Finally, it also makes the browser more secure, as it prevents malicious scripts from running on the CPU.

5. Don’t use addJavascriptInterface() unless absolutely necessary

The addJavascriptInterface() method allows JavaScript code to call methods in the Android application. This can be a security risk, as malicious JavaScript code could use this interface to access sensitive data or perform dangerous operations on the device. To mitigate this risk, Google recommends that developers only use this method when absolutely necessary and ensure that all input is properly sanitized before being passed into the Java layer.

To avoid using addJavascriptInterface(), developers should consider other options such as WebViewClient.shouldOverrideUrlLoading(). This method allows developers to intercept requests from the web page and handle them within the app instead of passing them through to the browser. This approach eliminates the need for addJavascriptInterface() and provides an additional layer of security by ensuring that any potentially malicious requests are blocked before they reach the browser.

Additionally, developers should also consider using third-party libraries such as Cordova or Crosswalk which provide their own APIs for interacting with native code. These libraries offer more secure alternatives to addJavascriptInterface() and allow developers to easily integrate native functionality into their apps without having to worry about potential security risks.

6. Validate all input from a web page before passing it to your application

Validating input is important because it helps to protect your application from malicious attacks. Attackers can use malicious code or scripts to inject data into a web page, which could then be passed on to the application and cause damage. By validating all input before passing it to the application, you can ensure that only legitimate data is being used.

The best way to validate input is to use an input validation library such as OWASP Validation Regex Library. This library provides regular expressions for common types of input, such as email addresses, URLs, phone numbers, etc., so that you can easily check if the input matches the expected format. You can also create custom regular expressions to match more specific types of input.

Once you have validated the input, you should also sanitize it by removing any potentially dangerous characters or HTML tags. This will help to further protect your application from malicious attacks.

7. Check for SSL errors and handle them appropriately

SSL (Secure Sockets Layer) is a protocol used to secure communication between two systems, such as a web server and a browser. It ensures that all data passed between the two systems remains private and integral. When using Android WebView, it’s important to check for SSL errors and handle them appropriately in order to ensure secure communication.

The first step in checking for SSL errors is to enable logging of SSL errors. This can be done by setting the WebViewClient’s onReceivedSslError() method to log any SSL errors encountered. Once enabled, the application should then check for these errors and take appropriate action. For example, if an error occurs, the application could display a warning message or redirect the user to a different page.

It’s also important to note that some devices may not support certain types of SSL certificates. In this case, the application should detect the unsupported certificate type and either prompt the user to accept the certificate or provide an alternative solution.

8. Disable zoom controls in the WebView

The zoom controls in the WebView allow users to pinch and zoom into a page, which can cause layout issues. This is because when the user zooms in, the content of the page may not scale properly or fit within the viewport. As a result, some elements on the page may be cut off or overlap with other elements.

Disabling the zoom controls helps ensure that the page will always display correctly regardless of how much the user zooms in. To disable the zoom controls, you need to set the built-in WebSettings object’s setBuiltInZoomControls() method to false. You can also use the setDisplayZoomControls() method to hide the zoom buttons from the UI.

It’s important to note that disabling the zoom controls does not prevent users from zooming in using their device’s accessibility settings. However, it does help ensure that the page will still look good even if they do so.

9. Monitor network requests and responses

Monitoring network requests and responses is important because it allows developers to identify any potential issues with the WebView. For example, if a request fails or takes too long to complete, this can be identified quickly and addressed accordingly. Additionally, monitoring network requests and responses helps developers understand how their application is performing in terms of speed and reliability.

To monitor network requests and responses, developers should use an Android debugging tool such as Chrome DevTools. This will allow them to view all the requests being made by the WebView, including headers, cookies, and other data. Developers can also use the Network tab to see the response time for each request, which can help them identify any performance issues.

Additionally, developers can use the Performance tab to measure the loading time of pages within the WebView. This can help them optimize the user experience by ensuring that pages are loaded quickly and efficiently. Finally, developers can use the Security tab to check for any security vulnerabilities in the WebView, such as cross-site scripting (XSS) attacks.

10. Implement caching strategies for faster loading times

Caching is a way of storing data in memory or on disk so that it can be accessed quickly. This helps to reduce the amount of time needed to load webpages, as well as reducing the amount of bandwidth used when loading them. By implementing caching strategies for Android WebView, developers can ensure that their users have a better experience with faster page loads and less waiting time.

There are several ways to implement caching strategies for Android WebView. One approach is to use an HTTP cache, which stores responses from web servers in order to reduce the number of requests sent to the server. This reduces the amount of time spent downloading resources, resulting in faster page loads. Additionally, developers can also use local storage to store static content such as images, JavaScript files, and CSS stylesheets. This allows the browser to access these resources without having to download them each time they are requested.