Android WebView addJavascriptInterface does not work if the webview is created in the callback of WebChromeClient#onCreateWindow

Question

The following is my test code. My problem is that in the page two I can not reference AndroidFunction2. I'm testing this on Nexus 7 with Android 4.4. But it's OK on sumsang i9100 with Android 4.0. Am I doing something wrong, or there is an Android's bug?

MainActivity

public class MainActivity extends Activity {
    WebView mWebView1;
    WebView mWebView2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final FrameLayout mainFrame = (FrameLayout) this.findViewById(R.id.mainFrame);

        mWebView1 = new WebView(this);
        mWebView1.getSettings().setJavaScriptEnabled(true);
        mWebView1.getSettings().setSupportMultipleWindows(true);
        mWebView1.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                return false;
            }
        });
        mWebView1.setWebChromeClient(new WebChromeClient() {
            @Override
            public boolean onCreateWindow(WebView view, boolean isDialog,
                    boolean isUserGesture, Message resultMsg) {
                mWebView2 = new WebView(MainActivity.this);
                mWebView2.getSettings().setJavaScriptEnabled(true);
                mWebView2.getSettings().setSupportMultipleWindows(true);
                mWebView2.setWebChromeClient(new WebChromeClient() {
                    @Override
                    public void onConsoleMessage(String message, int lineNumber, String sourceID) {
                        Log.d("WebView", "Line: " + lineNumber + ", " + message);
                    }
                });
                mWebView2.addJavascriptInterface(new Object() {
                    @JavascriptInterface
                    public void hello2() {
                    }
                }, "AndroidFunction2");

                (( WebViewTransport )resultMsg.obj).setWebView(mWebView2);
                resultMsg.sendToTarget();
                mainFrame.addView(mWebView2);
                return true;
            }
        });
        mWebView1.addJavascriptInterface(new Object() {
            @JavascriptInterface
            public void hello1() {
            }
        }, "AndroidFunction1");
        mWebView1.loadUrl("file:///sdcard/test_1.html");

        mainFrame.addView(mWebView1);
    }
}

And the two web page,

test_1.html:

<html>
<body>
    <a href="test_2.html" target="_blank">goto test 2</a>
    <div><a href="javascript:alert(typeof AndroidFunction1);"> alert(typeof AndroidFunction1);</a> </div>
    <div><a href="javascript:alert(typeof window.AndroidFunction1);"> alert(typeof window.AndroidFunction1);</a> </div>
</body>
</html>

test_2.html

<html>
<body>
    <div><a href="javascript:alert(AndroidFunction2);"> alert(AndroidFunction2);</a> </div>
    <div><a href="javascript:alert(typeof window.AndroidFunction2);"> alert(typeof window.AndroidFunction2);</a> </div>
</body>
</html>

@mntgoat sorry, I haven't. This problem still exists in my project. — zhang
– zhang, Commented Mar 18, 2014 at 11:53
@zhang Did you find out anyway to handle the internal 'AndroidFunction2' interface .? — Anukool srivastav
– Anukool srivastav, Commented Dec 4, 2018 at 11:35

Matt · Accepted Answer · 2015-09-02 10:09:52Z

52

Even I had the same problem and after going through the docs again I found that if you've set your targetSdkVersion to 17 or higher, you must add the @JavascriptInterface annotation to any method that you want available to your JavaScript (the method must also be public).

If you do not provide the annotation, the method is not accessible by your web page when running on Android 4.2 or higher.

The following example (taken from http://developer.android.com/guide/webapps/webview.html) shows that you can include the following class in your Android application:

public class WebAppInterface {
    Context mContext;

    /** Instantiate the interface and set the context */
    WebAppInterface(Context c) {
        mContext = c;
    }

    @JavascriptInterface   // must be added for API 17 or higher
    public void showToast(String toast) {
        Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
    }
}

and bind as

WebView webView = (WebView) findViewById(R.id.webview);
webView.addJavascriptInterface(new WebAppInterface(this), "Android");

and then call from the HTML inside the WebView as

<input type="button" value="Say hello" onClick="showAndroidToast('Hello Android!')" />

<script type="text/javascript">
    function showAndroidToast(toast) {
        Android.showToast(toast);
    }
</script>

edited Sep 2, 2015 at 10:09

Matt

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answered Jun 5, 2014 at 12:54

Ram Patra

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6 Comments

Matt Over a year ago

In future, do not copy content from elsewhere without clear attribution. It is seen as plagiarism. See stackoverflow.com/help/referencing

Ram Patra Over a year ago

@Matt I have mentioned in the first line "going through the docs" which means that my answer is derived from the official documentation. I am not against your point here but I have no intentions of copying contents either.

Matt Over a year ago

@Ramswaroop: I accept some effort was made to reference the documentation, but in situations where the data is copied (as it was for the examples), we really need clearer attribution.

Anukool srivastav Over a year ago

This work only on Main WebView, not on webview created from callback method onCreateWindow. Tried adding @JavascriptInterface also.

nagu Over a year ago

This solution doesnt seem to work for webview created from onCreateWindow method. I wonder how is this an accepted answer!!!!

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