How to clear cookies and cache of webview on Android when not in webview?

Question

Upon a user's sign out from my app I am clearing everything that may have been cached previously from the webview by calling this method:

 public void clearCookiesAndCache(Context context){
    CookieSyncManager.createInstance(context);
    CookieManager cookieManager = CookieManager.getInstance();

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        cookieManager.removeAllCookies(null);
    }
    else {
        cookieManager.removeAllCookie();
    }        
}

CookieSyncManager is marked as deprecated, however. CookieSyncManager.createInstance(context) is necessary to be called, however, if you have not loaded the webview previously. So how are we supposed to clear the cookies and cache without using the deprecated CookieSyncManager in cases where the webview may not have been previously loaded?

Answer 1

I use the following approach in my app:

    @SuppressWarnings("deprecation")
    public static void clearCookies(Context context)
    {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
            Log.d(C.TAG, "Using clearCookies code for API >=" + String.valueOf(Build.VERSION_CODES.LOLLIPOP_MR1));
            CookieManager.getInstance().removeAllCookies(null);
            CookieManager.getInstance().flush();
        } else
        {
            Log.d(C.TAG, "Using clearCookies code for API <" + String.valueOf(Build.VERSION_CODES.LOLLIPOP_MR1));
            CookieSyncManager cookieSyncMngr=CookieSyncManager.createInstance(context);
            cookieSyncMngr.startSync();
            CookieManager cookieManager=CookieManager.getInstance();
            cookieManager.removeAllCookie();
            cookieManager.removeSessionCookie();
            cookieSyncMngr.stopSync();
            cookieSyncMngr.sync();
        }
    }

Or in Kotlin

@SuppressWarnings("deprecation")
fun clearCookies(context: Context?) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
        CookieManager.getInstance().removeAllCookies(null)
        CookieManager.getInstance().flush()
    } else if (context != null) {
        val cookieSyncManager = CookieSyncManager.createInstance(context)
        cookieSyncManager.startSync()
        val cookieManager: CookieManager = CookieManager.getInstance()
        cookieManager.removeAllCookie()
        cookieManager.removeSessionCookie()
        cookieSyncManager.stopSync()
        cookieSyncManager.sync()
    }
}

I call this method in the following manner from my fragment:

mWebView.clearCache(true);
mWebView.clearHistory();
    
U.clearCookies(getActivity());
    
mWebView.loadUrl(authorizeURL);

It is possible to dump the cookies for a domain before and after the call to clearCookies by

String yahooCookies = CookieManager.getInstance().getCookie("https://yahoo.com");
Log.d(C.TAG, "Cookies for yahoo.com:" + yahooCookies);

After calling clearCookies yahooCookies will be null.

This implementation feeds my needs, I have tested it on several emulators and a prehistoric Samsung Galaxy Gio with Android 2.3.3 and Nexus 5 with Android 5.1.1.