Issue react-native-webview#3287: improve Download feature in Android

android/src/main/assets/SearchWebView.js

@@ -443,3 +443,22 @@ function getFavicons() {
   }
   window.FaviconWebView.postFavicon(`${favi}`);
 }
+
+function getBase64StringFromBlobUrl(blobUrl) {
+  const xhr = new XMLHttpRequest();
+  xhr.open('GET', blobUrl, true);
+  xhr.setRequestHeader('Content-type', 'application/octet-stream');
+  xhr.responseType = 'blob';
+  xhr.onload = () => {
+    if (xhr.status === 200) {
+      const blobResponse = xhr.response;
+      const fileReaderInstance = new FileReader();
+      fileReaderInstance.readAsDataURL(blobResponse);
+      fileReaderInstance.onloadend = () => {
+        const base64data = fileReaderInstance.result;
+        nativeScriptHandler.processBase64Data(base64data);
+      };
+    }
+  };
+  xhr.send();
+}

android/src/main/java/com/reactnativecommunity/webview/RNCWebViewManager.java

@@ -290,6 +290,12 @@ public void handleMessage(Message msg) {
 
     webView.setDownloadListener(new DownloadListener() {
       public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
+        if (url.startsWith("blob")) {
+          String jsConvert = "getBase64StringFromBlobUrl('" + url + "');";
+          webView.loadUrl("javascript:" + jsConvert);
+          return;
+        }
+
          // block non-http/https download links
         if (!URLUtil.isNetworkUrl(url)) {
           Toast.makeText(reactContext.getCurrentActivity(), R.string.download_protocol_not_supported,
@@ -1846,6 +1852,15 @@ public void run() {
           });
         }
       }
+
+      @JavascriptInterface
+      public void processBase64Data(String base64Data) {
+        RNCWebViewModule module = getModule((ReactContext) mContext.getContext());
+        module.setDownloadBase64Data(base64Data);
+        if (module.grantFileDownloaderPermissions()) {
+          module.saveBase64DataToFile();
+        }
+      }
     }
 
     public void captureScreen(String type) {

android/src/main/java/com/reactnativecommunity/webview/RNCWebViewModule.java

@@ -16,6 +16,8 @@
 import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
 import androidx.core.content.FileProvider;
+
+import android.util.Base64;
 import android.util.Log;
 import android.webkit.MimeTypeMap;
 import android.webkit.ValueCallback;
@@ -34,6 +36,8 @@
 
 import java.io.BufferedReader;
 import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
@@ -45,6 +49,7 @@
 import static android.app.Activity.RESULT_OK;
 
 import com.brave.adblock.Engine;
+import com.reactnativecommunity.webview.utils.Utils;
 
 @ReactModule(name = RNCWebViewModule.MODULE_NAME)
 public class RNCWebViewModule extends ReactContextBaseJavaModule implements ActivityEventListener {
@@ -67,6 +72,7 @@ public class RNCWebViewModule extends ReactContextBaseJavaModule implements Acti
   private Uri outputFileUri;
   private String intentTypeAfterPermissionGranted;
   private DownloadManager.Request downloadRequest;
+  private String downloadBase64Data;
   private PermissionListener webviewFileDownloaderPermissionListener = new PermissionListener() {
     @Override
     public boolean onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
@@ -77,6 +83,9 @@ public boolean onRequestPermissionsResult(int requestCode, String[] permissions,
             if (downloadRequest != null) {
               downloadFile();
             }
+            if (downloadBase64Data != null) {
+              saveBase64DataToFile();
+            }
           } else {
             Toast.makeText(getCurrentActivity().getApplicationContext(), "Cannot download files as permission was denied. Please provide permission to write to storage, in order to download files.", Toast.LENGTH_LONG).show();
           }
@@ -259,6 +268,48 @@ public void downloadFile() {
     Toast.makeText(getCurrentActivity().getApplicationContext(), downloadMessage, Toast.LENGTH_LONG).show();
   }
 
+  public void setDownloadBase64Data(String base64Data) {
+    this.downloadBase64Data = base64Data;
+  }
+
+  public void saveBase64DataToFile() {
+    if (downloadBase64Data != null) {
+      String fileName = String.valueOf(System.currentTimeMillis());
+      String fileExtension = Utils.getFileExtensionFromBase64Data(downloadBase64Data);
+      String mimeType = Utils.getMimeTypeFromBase64Data(downloadBase64Data);
+      if (fileExtension != null) {
+        fileName = fileName + "." + fileExtension;
+      }
+
+      try {
+        File downloadPath = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), fileName);
+        byte[] decodedData = Base64.decode(Utils.getBase64Data(downloadBase64Data), Base64.DEFAULT);
+        FileOutputStream fileOutputStream = new FileOutputStream(downloadPath, false);
+        fileOutputStream.write(decodedData);
+        fileOutputStream.flush();
+
+        if (downloadPath.exists()) {
+          Uri fileUri = FileProvider.getUriForFile(
+            getReactApplicationContext(),
+            getReactApplicationContext().getPackageName() + ".provider",
+            downloadPath
+          );
+          Utils.makeNotificationDownloadedBlobFile(getReactApplicationContext(), fileUri, mimeType, fileName);
+        }
+      } catch (FileNotFoundException e) {
+        e.printStackTrace();
+      } catch (IOException e) {
+        e.printStackTrace();
+      } catch (NullPointerException e) {
+        e.printStackTrace();
+      } catch (IllegalArgumentException e) {
+        e.printStackTrace();
+      }
+
+      downloadBase64Data = null;
+    }
+  }
+
   public boolean grantFileDownloaderPermissions() {
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
       return true;

android/src/main/java/com/reactnativecommunity/webview/utils/Utils.java

@@ -0,0 +1,85 @@
+package com.reactnativecommunity.webview.utils;
+
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.content.Intent;
+import android.net.Uri;
+import android.os.Build;
+
+import androidx.core.app.NotificationCompat;
+
+import com.reactnativecommunity.webview.R;
+
+public class Utils {
+
+  public static String getBase64Data(String base64Data) {
+    String[] parts = base64Data.split(",");
+    if (parts.length > 1) {
+      return parts[1];
+    }
+    return base64Data;
+  }
+
+  public static String getMimeTypeFromBase64Data(String base64Data) {
+    String[] parts = base64Data.split(";");
+    if (parts.length > 0) {
+      String[] typePart = parts[0].split(":");
+      if (typePart.length > 1) {
+        return typePart[1];
+      }
+    }
+    return null;
+  }
+
+  public static String getFileExtensionFromBase64Data(String base64Data) {
+    String[] parts = base64Data.split(";");
+    if (parts.length > 0) {
+      String[] extensionPart = parts[0].split("/");
+      if (extensionPart.length > 1) {
+        return extensionPart[1];
+      }
+    }
+    return null;
+  }
+
+  public static void makeNotificationDownloadedBlobFile(Context context, Uri fileUri, String mimeType, String fileName) {
+    Intent intent = new Intent(Intent.ACTION_VIEW);
+    intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
+    if (mimeType != null) {
+      intent.setDataAndType(fileUri, mimeType);
+    } else {
+      intent.setData(fileUri);
+    }
+    PendingIntent pendingIntent = PendingIntent.getActivity(
+      context, 0, intent,
+      PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_IMMUTABLE);
+
+    NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
+    String channel = "LunascapeChannel";
+
+    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(context, channel)
+      .setAutoCancel(true)
+      .setContentTitle("File downloaded")
+      .setContentText(fileName)
+      .setSmallIcon(R.drawable.ic_download_done_24)
+      .setWhen(System.currentTimeMillis())
+      .setPriority(Notification.PRIORITY_DEFAULT)
+      .setContentIntent(pendingIntent);
+
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+      NotificationChannel notificationChannel = new NotificationChannel(channel, channel, NotificationManager.IMPORTANCE_DEFAULT);
+      notificationChannel.setDescription(channel);
+      notificationChannel.enableLights(true);
+      notificationChannel.enableVibration(true);
+      notificationChannel.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
+      notificationManager.createNotificationChannel(notificationChannel);
+      notificationBuilder.setChannelId(channel);
+    }
+
+    notificationManager.notify(1, notificationBuilder.build());
+  }
+
+}

android/src/main/res/drawable/ic_download_done_24.xml

@@ -0,0 +1,6 @@
+<vector android:height="24dp" android:tint="#000000"
+    android:viewportHeight="24" android:viewportWidth="24"
+    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="@android:color/white" android:pathData="M20.13,5.41l-1.41,-1.41l-9.19,9.19l-4.25,-4.24l-1.41,1.41l5.66,5.66z"/>
+    <path android:fillColor="@android:color/white" android:pathData="M5,18h14v2h-14z"/>
+</vector>