How to open local PDF file in WebView in Android?

To open local PDF files in Android's WebView, you can follow these steps:

1. Add Permissions

First, add the following permissions in the AndroidManifest.xml file to allow your app to access the device's storage space:

xml
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

2. Configure WebView

Next, configure your WebView in your Activity or Fragment. Ensure JavaScript is enabled in WebView, as some PDF viewers (such as Google Docs) require JavaScript support.

java
WebView webView = findViewById(R.id.webView);
webView.getSettings().setJavaScriptEnabled(true);

3. Load PDF Files

There are several methods to load PDF files in WebView. A common approach is to use Google Docs Viewer as an intermediary to display the PDF. Convert the PDF file's path into a URL-encoded URI and load it via the Google Docs Viewer URL.

Example code:

Assume your PDF file is stored in the Download folder of local storage with the filename example.pdf:

java
String filePath = "file:///storage/emulated/0/Download/example.pdf";
String googleDocsUrl = "https://docs.google.com/gviewer?embedded=true&url=";
webView.loadUrl(googleDocsUrl + Uri.encode(filePath));

4. Handle File Paths

Note that hardcoding paths (e.g., /storage/emulated/0/) is not recommended for real devices, as paths may vary across different models. Instead, use Environment.getExternalStorageDirectory() to obtain the root path of external storage.

5. Security Considerations

When your app accesses external storage, address all security concerns, including user privacy and data protection. Starting from Android 6.0 (API level 23), users must grant permissions at runtime, so dynamically request permissions in your code.

Summary

By following these steps, you can successfully load and display local PDF files in Android's WebView. Using Google Docs Viewer is a convenient method as it avoids the complexity of directly handling PDF rendering within WebView. However, consider whether a more suitable method or third-party library might better meet your application's needs for efficient and secure file handling.