Added file upload support for Android

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 .DS_Store
+android/build

android/build.gradle

@@ -11,12 +11,12 @@ buildscript {
 apply plugin: 'com.android.library'
 
 android {
-    compileSdkVersion 23
-    buildToolsVersion "23.0.1"
+    compileSdkVersion 27
+    buildToolsVersion "27.0.3"
 
     defaultConfig {
         minSdkVersion 16
-        targetSdkVersion 23
+        targetSdkVersion 27
         versionCode 1
         versionName "1.0"
     }
@@ -30,5 +30,6 @@ repositories {
 }
 
 dependencies {
-    compile 'com.facebook.react:react-native:0.19.+'
+    compile "com.android.support:appcompat-v7:27.0.3"
+    compile "com.facebook.react:react-native:+" 
 }

android/src/main/AndroidManifest.xml

@@ -1,4 +1,6 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.github.alinz.reactnativewebviewbridge">
-
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
 </manifest>

android/src/main/java/com/github/alinz/reactnativewebviewbridge/AndroidWebViewModule.java

@@ -0,0 +1,261 @@
+package com.github.alinz.reactnativewebviewbridge;
+
+import android.Manifest;
+import android.annotation.TargetApi;
+import android.app.Activity;
+import android.app.DownloadManager;
+import android.content.ClipData;
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.net.Uri;
+import android.os.Build;
+import android.support.v4.content.ContextCompat;
+import android.util.Log;
+import android.webkit.ValueCallback;
+import android.widget.Toast;
+
+import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.bridge.ReactContextBaseJavaModule;
+import com.facebook.react.bridge.ActivityEventListener;
+import com.facebook.react.common.annotations.VisibleForTesting;
+import com.facebook.react.modules.core.PermissionAwareActivity;
+import com.facebook.react.modules.core.PermissionListener;
+
+import android.webkit.JavascriptInterface;
+import android.webkit.WebView;
+
+import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.bridge.WritableMap;
+import com.facebook.react.modules.core.DeviceEventManagerModule;
+import com.facebook.react.uimanager.events.RCTEventEmitter;
+
+
+public class AndroidWebViewModule extends ReactContextBaseJavaModule implements ActivityEventListener {
+    private ValueCallback<Uri> mUploadMessage;
+    private ValueCallback<Uri[]> mUploadCallbackAboveL;
+    private DownloadManager.Request downloadRequest;
+    private static final int FILE_CHOOSER_PERMISSION_REQUEST = 1;
+    private static final int FILE_DOWNLOAD_PERMISSION_REQUEST = 2;
+
+    @VisibleForTesting
+    public static final String REACT_CLASS = "AndroidWebViewModule";
+
+    private WebView webView;
+    private ReactApplicationContext reactContext;
+
+    public void JavascriptBridge(WebView webView) {
+        this.webView = webView;
+    }
+
+    @JavascriptInterface
+    public void send(String message) {
+        WritableMap event = Arguments.createMap();
+        event.putString("message", message);
+        ReactContext reactContext = (ReactContext) this.webView.getContext();
+        reactContext.getJSModule(RCTEventEmitter.class).receiveEvent(
+                this.webView.getId(),
+                "topChange",
+                event);
+    }
+
+    public AndroidWebViewModule(ReactApplicationContext context){
+        super(context);
+        context.addActivityEventListener(this);
+    }
+
+    private WebViewBridgePackage aPackage;
+
+    public void setPackage(WebViewBridgePackage aPackage) {
+        this.aPackage = aPackage;
+    }
+
+    public WebViewBridgePackage getPackage() {
+        return this.aPackage;
+    }
+
+    public void setContext( ReactApplicationContext context )
+    {
+        this.reactContext = context;
+    }
+
+    public ReactApplicationContext getContext()
+    {
+        return this.reactContext;
+    }
+
+    @Override
+    public String getName(){
+        return REACT_CLASS;
+    }
+
+    @SuppressWarnings("unused")
+    public Activity getActivity() {
+        return getCurrentActivity();
+    }
+
+    public void setUploadMessage(ValueCallback<Uri> uploadMessage) {
+        mUploadMessage = uploadMessage;
+    }
+
+    public void setmUploadCallbackAboveL(ValueCallback<Uri[]> mUploadCallbackAboveL) {
+        this.mUploadCallbackAboveL = mUploadCallbackAboveL;
+    }
+
+    public void setDownloadRequest(DownloadManager.Request request) {
+        this.downloadRequest = request;
+    }
+
+    @Override
+    public void onActivityResult(Activity activity, int requestCode, int resultCode, Intent data) {
+        // super.onActivityResult(requestCode, resultCode, data);
+        if (requestCode == 1) {
+            if (null == mUploadMessage && null == mUploadCallbackAboveL){
+                return;
+            }
+            Uri result = data == null || resultCode != Activity.RESULT_OK ? null : data.getData();
+            if (mUploadCallbackAboveL != null) {
+                onActivityResultAboveL(requestCode, resultCode, data);
+            } else if (mUploadMessage != null) {
+                mUploadMessage.onReceiveValue(result);
+                mUploadMessage = null;
+            }
+        }
+    }
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+    private void onActivityResultAboveL(int requestCode, int resultCode, Intent data) {
+        if (requestCode != 1 || mUploadCallbackAboveL == null) {
+            return;
+        }
+        Uri[] results = null;
+        if (resultCode == Activity.RESULT_OK) {
+            if (data != null) {
+                String dataString = data.getDataString();
+                ClipData clipData = data.getClipData();
+                if (clipData != null) {
+                    results = new Uri[clipData.getItemCount()];
+                    for (int i = 0; i < clipData.getItemCount(); i++) {
+                        ClipData.Item item = clipData.getItemAt(i);
+                        results[i] = item.getUri();
+                    }
+                }
+                if (dataString != null)
+                    results = new Uri[]{Uri.parse(dataString)};
+            }
+        }
+        mUploadCallbackAboveL.onReceiveValue(results);
+        mUploadCallbackAboveL = null;
+    }
+
+    public void openFileChooserView(){
+        try {
+            Intent openableFileIntent = new Intent(Intent.ACTION_GET_CONTENT);
+            openableFileIntent.addCategory(Intent.CATEGORY_OPENABLE);
+            openableFileIntent.setType("*/*");
+
+            final Intent chooserIntent = Intent.createChooser(openableFileIntent, "Choose File");
+            getActivity().startActivityForResult(chooserIntent, 1);
+        } catch (Exception e) {
+            Log.d("customwebview", e.toString());
+        }
+    }
+
+    public void downloadFile() {
+        DownloadManager dm = (DownloadManager) getActivity().getBaseContext().getSystemService(Context.DOWNLOAD_SERVICE);
+        String downloadMessage = "Downloading";
+
+        dm.enqueue(this.downloadRequest);
+
+        Toast.makeText(getActivity().getApplicationContext(), downloadMessage, Toast.LENGTH_LONG).show();
+    }
+
+    // NB: parts of the permission management are adapted, with significant modification, from 
+    //   https://lakshinkarunaratne.wordpress.com/2018/03/11/enhancing-the-react-native-webview-part-2-supporting-file-downloads-in-android/
+
+    private PermissionAwareActivity getPermissionAwareActivity() {
+        Activity activity = getCurrentActivity();
+        if (activity == null) {
+            throw new IllegalStateException("Tried to use permissions API while not attached to an " +
+                    "Activity.");
+        } else if (!(activity instanceof PermissionAwareActivity)) {
+            throw new IllegalStateException("Tried to use permissions API but the host Activity doesn't" +
+                    " implement PermissionAwareActivity.");
+        }
+        return (PermissionAwareActivity) activity;
+    }
+
+    private PermissionListener webviewFileChooserPermissionListener = new PermissionListener() {
+        @Override
+        public boolean onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+            switch (requestCode) {
+                case FILE_CHOOSER_PERMISSION_REQUEST: {
+                    // If request is cancelled, the result arrays are empty.
+                    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                        if (mUploadCallbackAboveL != null){
+                            openFileChooserView();
+                        }
+                    } else {
+                        Toast.makeText(getActivity().getApplicationContext(), "Cannot upload files as permission was denied. Please provide permission to access storage, in order to upload files.", Toast.LENGTH_LONG).show();
+                    }
+                    return true;
+                }
+            }
+            return false;
+        }
+    };
+
+    private PermissionListener webviewFileDownloaderPermissionListener = new PermissionListener() {
+        @Override
+        public boolean onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+            switch (requestCode) {
+                case FILE_DOWNLOAD_PERMISSION_REQUEST: {
+                    // If request is cancelled, the result arrays are empty.
+                    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                        if(downloadRequest != null){
+                            downloadFile();
+                        }
+                    } else {
+                        Toast.makeText(getActivity().getApplicationContext(), "Cannot download files as permission was denied. Please provide permission to write to storage, in order to download files.", Toast.LENGTH_LONG).show();
+                    }
+                    return true;
+                }
+            }
+            return false;
+        }
+    };
+
+    public boolean grantFileChooserPermissions() {
+        if(Build.VERSION.SDK_INT < Build.VERSION_CODES.M){
+            return true;
+        }
+        boolean result = true;
+        if (ContextCompat.checkSelfPermission(this.getActivity(),Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
+            result = false;
+        }
+
+        if(!result){
+            PermissionAwareActivity activity = getPermissionAwareActivity();
+            activity.requestPermissions(new String[]{ Manifest.permission.READ_EXTERNAL_STORAGE }, FILE_CHOOSER_PERMISSION_REQUEST, webviewFileChooserPermissionListener);
+        }
+        return result;
+    }
+
+    public boolean grantFileDownloaderPermissions() {
+        if(Build.VERSION.SDK_INT < Build.VERSION_CODES.M){
+            return true;
+        }
+        boolean result = true;
+        if (ContextCompat.checkSelfPermission(this.getActivity(),Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
+            result = false;
+        }
+
+        if(!result){
+            PermissionAwareActivity activity = getPermissionAwareActivity();
+            activity.requestPermissions(new String[]{ Manifest.permission.WRITE_EXTERNAL_STORAGE }, FILE_DOWNLOAD_PERMISSION_REQUEST, webviewFileDownloaderPermissionListener);
+        }
+        return result;
+    }
+
+    public void onNewIntent(Intent intent) {}
+}