android: add webview postMessage

.gitignore

@@ -14,3 +14,7 @@ example/ios/Podfile.lock
 **/Flutter/Generated.xcconfig/
 **/Flutter/flutter_assets/
 
+.settings
+.classpath
+.project
+.vscode

README.md

@@ -93,6 +93,7 @@ flutterWebviewPlugin.launch(url,
 - `Stream<String>` onUrlChanged
 - `Stream<WebViewStateChanged>` onStateChanged
 - `Stream<String>` onError
+- `Stream<String>` onWebviewMessage
 
 ***Don't forget to dispose webview***
 `flutterWebviewPlugin.dispose()`
@@ -111,7 +112,9 @@ Future<Null> launch(String url,
          String userAgent: null,
          bool withZoom: false,
          bool withLocalStorage: true,
-         bool scrollBar: true});
+         bool scrollBar: true,
+         bool enableMessaging: false,
+         });
 ```
 ```dart
 Future<String> evalJavascript(String code);
@@ -131,3 +134,7 @@ Future<Null> hide();
 ```dart
 Future<Null> reloadUrl(String url);
 ```
+
+```dart
+Future<Null> linkBridge();
+```

android/src/main/java/com/flutter_webview_plugin/FlutterWebviewPlugin.java

@@ -1,6 +1,5 @@
 package com.flutter_webview_plugin;
 
-
 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
@@ -38,42 +37,48 @@ private FlutterWebviewPlugin(Activity activity) {
     @Override
     public void onMethodCall(MethodCall call, MethodChannel.Result result) {
         switch (call.method) {
-            case "launch":
-                openUrl(call, result);
-                break;
-            case "close":
-                close(call, result);
-                break;
-            case "eval":
-                eval(call, result);
-                break;
-            case "resize":
-                resize(call, result);
-                break;
-            case "reload":
-                reload(call, result);
-                break;
-            case "back":
-                back(call, result);
-                break;
-            case "forward":
-                forward(call, result);
-                break;
-            case "hide":
-                hide(call, result);
-                break;
-            case "show":
-                show(call, result);
-                break;
-            case "reloadUrl":
-                reloadUrl(call, result);
-                break;
-            case "stopLoading":
-                stopLoading(call, result);
-                break;				
-            default:
-                result.notImplemented();
-                break;
+        case "launch":
+            openUrl(call, result);
+            break;
+        case "close":
+            close(call, result);
+            break;
+        case "eval":
+            eval(call, result);
+            break;
+        case "resize":
+            resize(call, result);
+            break;
+        case "reload":
+            reload(call, result);
+            break;
+        case "back":
+            back(call, result);
+            break;
+        case "forward":
+            forward(call, result);
+            break;
+        case "hide":
+            hide(call, result);
+            break;
+        case "show":
+            show(call, result);
+            break;
+        case "reloadUrl":
+            reloadUrl(call, result);
+            break;
+        case "stopLoading":
+            stopLoading(call, result);
+            break;
+        case "postMessage":
+            postMessage(call, result);
+            break;
+        case "linkBridge":
+            linkBridge(call, result);
+            break;
+        default:
+            result.notImplemented();
+            break;
         }
     }
 
@@ -88,6 +93,7 @@ private void openUrl(MethodCall call, MethodChannel.Result result) {
         boolean withLocalStorage = call.argument("withLocalStorage");
         Map<String, String> headers = call.argument("headers");
         boolean scrollBar = call.argument("scrollBar");
+        boolean enableMessaging = call.argument("enableMessaging");
 
         if (webViewManager == null || webViewManager.closed == true) {
             webViewManager = new WebviewManager(activity);
@@ -97,28 +103,19 @@ private void openUrl(MethodCall call, MethodChannel.Result result) {
 
         activity.addContentView(webViewManager.webView, params);
 
-        webViewManager.openUrl(withJavascript,
-                clearCache,
-                hidden,
-                clearCookies,
-                userAgent,
-                url,
-                headers,
-                withZoom,
-                withLocalStorage,
-                scrollBar
-        );
+        webViewManager.openUrl(withJavascript, clearCache, hidden, clearCookies, userAgent, url, headers, withZoom,
+                withLocalStorage, scrollBar, enableMessaging);
         result.success(null);
     }
 
     private FrameLayout.LayoutParams buildLayoutParams(MethodCall call) {
         Map<String, Number> rc = call.argument("rect");
         FrameLayout.LayoutParams params;
         if (rc != null) {
-            params = new FrameLayout.LayoutParams(
-                    dp2px(activity, rc.get("width").intValue()), dp2px(activity, rc.get("height").intValue()));
-            params.setMargins(dp2px(activity, rc.get("left").intValue()), dp2px(activity, rc.get("top").intValue()),
-                    0, 0);
+            params = new FrameLayout.LayoutParams(dp2px(activity, rc.get("width").intValue()),
+                    dp2px(activity, rc.get("height").intValue()));
+            params.setMargins(dp2px(activity, rc.get("left").intValue()), dp2px(activity, rc.get("top").intValue()), 0,
+                    0);
         } else {
             Display display = activity.getWindowManager().getDefaultDisplay();
             Point size = new Point();
@@ -132,7 +129,7 @@ private FrameLayout.LayoutParams buildLayoutParams(MethodCall call) {
     }
 
     private void stopLoading(MethodCall call, MethodChannel.Result result) {
-        if (webViewManager != null){
+        if (webViewManager != null) {
             webViewManager.stopLoading(call, result);
         }
     }
@@ -144,47 +141,40 @@ private void close(MethodCall call, MethodChannel.Result result) {
         }
     }
 
-    /** 
-    * Navigates back on the Webview.
-    */
+    /**
+     * Navigates back on the Webview.
+     */
     private void back(MethodCall call, MethodChannel.Result result) {
         if (webViewManager != null) {
             webViewManager.back(call, result);
         }
     }
-    /** 
-    * Navigates forward on the Webview.
-    */
+
+    /**
+     * Navigates forward on the Webview.
+     */
     private void forward(MethodCall call, MethodChannel.Result result) {
         if (webViewManager != null) {
             webViewManager.forward(call, result);
         }
     }
 
-    /** 
-    * Reloads the Webview.
-    */
+    /**
+     * Reloads the Webview.
+     */
     private void reload(MethodCall call, MethodChannel.Result result) {
         if (webViewManager != null) {
             webViewManager.reload(call, result);
         }
     }
+
     private void reloadUrl(MethodCall call, MethodChannel.Result result) {
         if (webViewManager != null) {
             String url = call.argument("url");
-            webViewManager.openUrl(false,
-                    false,
-                    false,
-                    false,
-                    "",
-                    url,
-                    null,
-                    false,
-                    false,
-                    false
-            );
+            webViewManager.openUrl(false, false, false, false, "", url, null, false, false, false, false);
         }
     }
+
     private void eval(MethodCall call, final MethodChannel.Result result) {
         if (webViewManager != null) {
             webViewManager.eval(call, result);
@@ -198,11 +188,13 @@ private void resize(MethodCall call, final MethodChannel.Result result) {
         }
         result.success(null);
     }
+
     private void hide(MethodCall call, final MethodChannel.Result result) {
         if (webViewManager != null) {
             webViewManager.hide(call, result);
         }
     }
+
     private void show(MethodCall call, final MethodChannel.Result result) {
         if (webViewManager != null) {
             webViewManager.show(call, result);
@@ -216,9 +208,21 @@ private int dp2px(Context context, float dp) {
 
     @Override
     public boolean onActivityResult(int i, int i1, Intent intent) {
-        if(webViewManager != null && webViewManager.resultHandler != null){
+        if (webViewManager != null && webViewManager.resultHandler != null) {
             return webViewManager.resultHandler.handleResult(i, i1, intent);
         }
         return false;
     }
+
+    private void postMessage(MethodCall call, final MethodChannel.Result result) {
+        if (webViewManager != null) {
+            webViewManager.postMessage(call, result);
+        }
+    }
+
+    private void linkBridge(MethodCall call, final MethodChannel.Result result) {
+        if (webViewManager != null) {
+            webViewManager.linkBridge();
+        }
+    }
 }

android/src/main/java/com/flutter_webview_plugin/WebviewManager.java

@@ -24,6 +24,11 @@
 
 import static android.app.Activity.RESULT_OK;
 
+import android.webkit.JavascriptInterface;
+import java.net.URLEncoder;
+import java.io.UnsupportedEncodingException;
+import org.json.JSONException;
+import org.json.JSONObject;
 /**
  * Created by lejard_h on 20/12/2017.
  */
@@ -33,6 +38,7 @@ class WebviewManager {
     private ValueCallback<Uri> mUploadMessage;
     private ValueCallback<Uri[]> mUploadMessageArray;
     private final static int FILECHOOSER_RESULTCODE=1;
+    private static final String CHANNEL_NAME = "flutter_webview_plugin";
 
     @TargetApi(7)
     class ResultHandler {
@@ -189,7 +195,7 @@ private void clearCache() {
         webView.clearFormData();
     }
 
-    void openUrl(boolean withJavascript, boolean clearCache, boolean hidden, boolean clearCookies, String userAgent, String url, Map<String, String> headers, boolean withZoom, boolean withLocalStorage, boolean scrollBar) {
+    void openUrl(boolean withJavascript, boolean clearCache, boolean hidden, boolean clearCookies, String userAgent, String url, Map<String, String> headers, boolean withZoom, boolean withLocalStorage, boolean scrollBar, boolean messagingEnabled) {
         webView.getSettings().setJavaScriptEnabled(withJavascript);
         webView.getSettings().setBuiltInZoomControls(withZoom);
         webView.getSettings().setSupportZoom(withZoom);
@@ -220,6 +226,11 @@ void openUrl(boolean withJavascript, boolean clearCache, boolean hidden, boolean
         } else {
             webView.loadUrl(url);
         }
+
+        if (messagingEnabled) {
+            enableMessaging();
+        }
+
     }
 
     void close(MethodCall call, MethodChannel.Result result) {
@@ -307,4 +318,60 @@ void stopLoading(MethodCall call, MethodChannel.Result result){
             webView.stopLoading();
         }
     }
+
+    protected static class JsObject {
+        WebviewManager webviewManager;
+
+        JsObject(WebviewManager _webviewManager) {
+            webviewManager = _webviewManager;
+        }
+
+        @JavascriptInterface
+        public void postMessage(String message) {
+            webviewManager.onMessage(message);
+        }
+    }
+
+    public void onMessage(String message) {
+        FlutterWebviewPlugin.channel.invokeMethod("onWebviewMessage", message);
+    }
+
+    public void postMessage(MethodCall call, final MethodChannel.Result result) {
+        String message = call.argument("data");
+        try {
+            JSONObject eventInitDict = new JSONObject();
+            eventInitDict.put("data", message);
+            String script = "(function () {" +
+                "var event;" +
+                "var data = " + eventInitDict.toString() + ";" +
+                "try {" +
+                "event = new MessageEvent('message', data);" +
+                "} catch (e) {" +
+                "event = document.createEvent('MessageEvent');" +
+                "event.initMessageEvent('message', true, true, data.data, data.origin, data.lastEventId, data.source);" +
+                "}" +
+                "document.dispatchEvent(event);" +
+            "})();";
+            webView.evaluateJavascript(script, null);
+
+        } catch (JSONException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    protected void enableMessaging() {
+        webView.addJavascriptInterface(new JsObject(this), CHANNEL_NAME);
+    }
+
+
+    protected void linkBridge() {
+        String script = "(" +
+                "window.originalPostMessage = window.postMessage," +
+                "window.postMessage = function(data) {" +
+                CHANNEL_NAME + ".postMessage(String(data));" +
+                "}" +
+                ")";
+
+        webView.evaluateJavascript(script, null);
+    }
 }