I have a webservice that I am trying to authenticate with in the background using a webview. When I initially send the request it will work appropriately (failure/success based on credentials), but after it seems like I am getting a cached response.

Here is my webview setup code:

WebView browser = new WebView(this);
WebSettings settings = browser.getSettings();
settings.setJavaScriptEnabled(true);
settings.setSavePassword(false);
settings.setCacheMode(WebSettings.LOAD_NO_CACHE);
settings.setAppCacheEnabled(false);
browser.setWebChromeClient(new WebChromeClient() {
    public void onProgressChanged(WebView view, int progress) {
    Log.d("BROWSERPROGRESS", Integer.toString(progress));
}
});
jsInterface = new AddAccountJSInterface();
browser.addJavascriptInterface(jsInterface, "ADDACCOUNTJSINTERFACE");
browser.setWebViewClient(new AddAccountClient(this));

So as you may see I have two additional classes controlling my webView:

1. An object that provides an interface for javascript (AddAccountJSInterface)
2. A WebViewClient

Additionally I do have a WebChromeClient, but it's only there for debugging and I'm pretty sure that it won't interfere with anything.

The JS interface simply provides an easy way of getting the body HTML for performing analysis, so I'm confident that isn't the issue either.

The WebViewClient has the following code in it which does most of the "custom" work for routing based on various responses from the webservice.

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if(url.contains(INSTALL_PREFIX)) {
            HashMap<String, String> params = extractParameters(url);
            verificationComplete(params);
            return true;
        }
        return false;
    }

    @Override
    public void onPageFinished(WebView view, String url){
        if(invalidShop(view)) {
            Toast.makeText(context, context.getString(R.string.no_find_shop), Toast.LENGTH_SHORT).show();
            shopAddressField.requestFocus();
            replaceUiElements(loadingBar, addAccountButton);
        } else if(url.contains(ADMIN_AUTH_LOGIN)) {
            if(invalidLogin(view)) {
                Toast.makeText(context, context.getString(R.string.invalid_login),Toast.LENGTH_SHORT).show();
                emailField.requestFocus();
                replaceUiElements(loadingBar, addAccountButton);
            } else {
                String email = emailField.getText().toString();
                String password = passwordField.getText().toString();
                String submitJS = String.format(FORM_SUBMISSION_JS, email, password);

                jsInterface.setInnerHTML("");

                browser.loadUrl(submitJS);
            }
        }
    }

In my activity I have 3 text fields that I need to fill followed by clicking a button to submit it. The activity then takes in the data from 3 text fields (shopAddressField, usernameField, passwordField) and then executes some javascript that populates some form data (which was loaded in the invisible webView) then clicks the submit button.

It is the last part that is messing up, which appears to be caching the response from the server (perhaps using cookies?) and return that instead of asking the server if the data is correct or not.

A bit of clarification:

JSInterface is simply a Java object that allows me to execute javascript on my webview which is tied to a function within that object. In my case my JSInterface has one function which is setInnerHtml(String html).

This is the javascript that is executed on the webview:

javascript:window.ADDACOUNTJSINTERFACE.setInnerHTML(document.body.innerHTML)

And this is the setInnerHtml function:

public void setInnerHtml(String innerHtml) {
    this.innerHtml = innerHtml;
}

So when I actually execute jsInterface.setInnerHtml("") I'm just over-writing the HTML that was pulled in (to be sure I'm not getting my old data from there for some reason).

As for my submitJS it is once again some Javascript that is executed on my webView as follows:

// submitJS will be something like this once all the credentials have been set
// Note: I know that the server will make jQuery available
// Note: Much of the Java string formatting has been removed to help clarify
// the code.
String submitJS = 
    "javascript:(function() {
        $('login-input').value='username';
        $('password').value='password';
        $('sign-in-form').up().submit();
    })()"
// I then simply get the webview to execute the javascript above
webView.loadData(submitJS);

I have a webservice that I am trying to authenticate with in the background using a webview. When I initially send the request it will work appropriately (failure/success based on credentials), but after it seems like I am getting a cached response.

Here is my webview setup code:

WebView browser = new WebView(this);
WebSettings settings = browser.getSettings();
settings.setJavaScriptEnabled(true);
settings.setSavePassword(false);
settings.setCacheMode(WebSettings.LOAD_NO_CACHE);
settings.setAppCacheEnabled(false);
browser.setWebChromeClient(new WebChromeClient() {
    public void onProgressChanged(WebView view, int progress) {
    Log.d("BROWSERPROGRESS", Integer.toString(progress));
}
});
jsInterface = new AddAccountJSInterface();
browser.addJavascriptInterface(jsInterface, "ADDACCOUNTJSINTERFACE");
browser.setWebViewClient(new AddAccountClient(this));

So as you may see I have two additional classes controlling my webView:

1. An object that provides an interface for javascript (AddAccountJSInterface)
2. A WebViewClient

Additionally I do have a WebChromeClient, but it's only there for debugging and I'm pretty sure that it won't interfere with anything.

The JS interface simply provides an easy way of getting the body HTML for performing analysis, so I'm confident that isn't the issue either.

The WebViewClient has the following code in it which does most of the "custom" work for routing based on various responses from the webservice.

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if(url.contains(INSTALL_PREFIX)) {
            HashMap<String, String> params = extractParameters(url);
            verificationComplete(params);
            return true;
        }
        return false;
    }

    @Override
    public void onPageFinished(WebView view, String url){
        if(invalidShop(view)) {
            Toast.makeText(context, context.getString(R.string.no_find_shop), Toast.LENGTH_SHORT).show();
            shopAddressField.requestFocus();
            replaceUiElements(loadingBar, addAccountButton);
        } else if(url.contains(ADMIN_AUTH_LOGIN)) {
            if(invalidLogin(view)) {
                Toast.makeText(context, context.getString(R.string.invalid_login),Toast.LENGTH_SHORT).show();
                emailField.requestFocus();
                replaceUiElements(loadingBar, addAccountButton);
            } else {
                String email = emailField.getText().toString();
                String password = passwordField.getText().toString();
                String submitJS = String.format(FORM_SUBMISSION_JS, email, password);

                jsInterface.setInnerHTML("");

                browser.loadUrl(submitJS);
            }
        }
    }

In my activity I have 3 text fields that I need to fill followed by clicking a button to submit it. The activity then takes in the data from 3 text fields (shopAddressField, usernameField, passwordField) and then executes some javascript that populates some form data (which was loaded in the invisible webView) then clicks the submit button.

It is the last part that is messing up, which appears to be caching the response from the server (perhaps using cookies?) and return that instead of asking the server if the data is correct or not.

A bit of clarification:

JSInterface is simply a Java object that allows me to execute javascript on my webview which is tied to a function within that object. In my case my JSInterface has one function which is setInnerHtml(String html).

This is the javascript that is executed on the webview:

javascript:window.ADDACOUNTJSINTERFACE.setInnerHTML(document.body.innerHTML)

And this is the setInnerHtml function:

public void setInnerHtml(String innerHtml) {
    this.innerHtml = innerHtml;
}

So when I actually execute jsInterface.setInnerHtml("") I'm just over-writing the HTML that was pulled in (to be sure I'm not getting my old data from there for some reason).

As for my submitJS it is once again some Javascript that is executed on my webView as follows:

// submitJS will be something like this once all the credentials have been set
// Note: I know that the server will make jQuery available
// Note: Much of the Java string formatting has been removed to help clarify
// the code.
String submitJS = 
    "javascript:(function() {
        $('login-input').value='username';
        $('password').value='password';
        $('sign-in-form').up().submit();
    })()"
// I then simply get the webview to execute the javascript above
webView.loadData(submitJS);

• javascript
• android
• android-webview

• 3 Complaining on Twitter that your question isn't getting attention after only 45 minutes is insulting. If you want guaranteed sub-hour responses, hire a consultant. In the meantime, please consider explaining what jsInterface.setInnerHTML(""); and submitJS are, since you say they are where your problem lies. – CommonsWare Commented Feb 9, 2011 at 21:19
• Apologies. I've added some more details about what exactly the javascript is doing and how I'm using my jsInterface java object. I hope this helps clarify the question some more. – csaunders Commented Feb 9, 2011 at 21:46
• Complement with this one: "android.permission.DELETE_CACHE_FILES" on manifest file. – Franklin Hirata Commented Dec 4, 2013 at 19:31

1 Answer 1

So it turns out the problem wasn't based around the Caching, and possibly not cookies.

When executing javascript on your webView it does this in a separate thread and can be quite slow. This lead to a race condition which caused code to be executed in the wrong order.

I've solved this problem by using a Semaphore as a Mutex. This allows me to prevent my getter from returning before the Javascript on the webView is able to execute.

The interface I created now looks like this:

private class AddAccountJSInterface {
    private final String TAG = getClass().getName().toUpperCase();
    private Semaphore mutex = new Semaphore(1, false);
    private String innerHTML;

    public void aquireSemaphore() {
        Log.d(TAG, "Attempting to lock semaphore");
        try {
            mutex.acquire();
        } catch(InterruptedException e) {
            Log.d(TAG, "Oh snap, we got interrupted.  Just going to abort.");
            return;
        }
        Log.d(TAG, "Semaphore has been aquired");
    }

    @SuppressWarnings("unused")
    public void setInnerHTML(String html) {
            this.innerHTML = html;
            Log.d(TAG, "setInnerHTML is now releasing semaphore.");
            mutex.release();
            Log.d(TAG, "setInnerHTML has successfully released the semaphore.");
    }

    public synchronized String getInnerHTML() {
        Log.d(TAG, "getInnerHTML attempting to aquire semaphore, may block...");
        String innerHTML = "";
        try {
            mutex.acquire();

            Log.d(TAG, "getInnerHTML has aquired the semaphore, grabbing data.");
            innerHTML = this.innerHTML;

            Log.d(TAG, "getInnerHTML no longer needs semaphore, releasing");
            mutex.release();
        } catch (InterruptedException e) {
            Log.d(TAG, "Something has gone wrong while attempting to aquire semaphore, aborting");
        }

        return innerHTML;
    }
}

Now the way I use this in my code is as follows:

// I have access to the jsInterface object which is an instance of the class above as well as a webView which I will be executing the javascript on.
String getInnerHtmlJS = "javascript:window.MYJSINTERFACE.setInnerHTML(document.body.innerHTML);"
jsInterface.aquireSemaphore()
// Execute my JS on the webview
jsInterface.loadUrl(getInnerHtmlJS)
// Now we get our inner HTML
// Note: getInnerHTML will block since it must wait for the setInnerHTML (executed via the JS) function to release the semaphore
String theInnerHTML = jsInterface.getInnerHTML();