I am currently creating an android application.
The aim of the application is to fire off some injected JavaScript code into the WebView that I have created within my android application. The problem that I am having is that the action that has been injected doesn't work.
You should also be aware that the html page that I am loading has been created locally. aim of the application is to have a toast message display.The code listing is below:
//uses javascript that is in the local HTML file
public class MainActivity extends Activity {
final String URL = "file:///android_asset/index.html";
private WebView myWebView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
WebView myWebView = (WebView) findViewById(R.id.webview);
WebSettings webSettings = myWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
myWebView.addJavascriptInterface(new WebAppInterface(this), "Android");
String test= "test";
String javascript ="javascript:document.addEventListener('click', function(){Android.showToast(toast)})";
myWebView.loadUrl(javascript);
myWebView.loadUrl(URL);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public class WebAppInterface {
Context mContext;
/** Instantiate the interface and set the context */
WebAppInterface(Context c) {
mContext = c;
}
/** Show a toast from the web page */
#JavascriptInterface
public void showToast(String toast) {
Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
}
}
}
There are several issues with your implementation.
The toast variable might not be defined in the scope of your callback. Also, you are missing two semicolons, one right after calling the showToast method, and the other one at the end of the addEventListener method which results in a syntax error.
Finally, you are loading the Javascript code before loading the page, which gets it invalidated. You should be injecting your javascript code after the webpage has finished loading such as in the below example.
I've taken your example and rewrote it in a custom app to make sure it was working. Here's what I've written :
Android :
// Registering the JS interface
mWebView.addJavascriptInterface(new JSInterface(), "JSInterface");
// Waiting for the page to be fully loaded, and injecting the JS code
mWebView.setWebViewClient(new WebViewClient() {
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
return false;
}
#Override
public void onPageFinished(WebView view, String url) {
view.loadUrl(INJECTED_CODE);
}
});
// Load your custom url
mWebView.loadUrl(YOUR_ACTUAL_URL);
/**
* Interface between Java and Javascript.
*/
public class JSInterface {
#JavascriptInterface
public void showToast(String toast) {
Log.d("debug", "I got : " + toast);
}
}
Injected javascript :
public static final String INJECTED_CODE = "javascript:"
+ "(function() { "
+ "document.addEventListener('click', function(){JSInterface.showToast('Hello Android !');});"
+ "})()";
You are attempting to call that JS code before loading your html page.
I would guess that the document object is not ready.
Change your event listener and bind to the window
From:
String javascript ="javascript:document.addEventListener('click', function(){Android.showToast(toast)})";
To:
String javascript ="javascript:window.addEventListener('click', function(){Android.showToast(toast)})";
And you should get a result. If not what is logcat spitting out when you click?
EDIT: Just saw Halim Qarroums onPageFinished solution, that is probably a better one in your case.
Related
I developed a simple webview app. I added a button which should act as the back button, so users can navigate back one page.
The button is initially hidden and should only show if a back history exists.
How can I realise this?
The code is simple:
backButton = findViewById(R.id.backButton);
backButton.setEnabled(blizzView.canGoBack());
but where do I have to call this? How is the "some site loaded" event called?
Update:
I tried to apply #Murats answer, but nothing happens:
private WebView blizzView; // my webview
private Button backButton;
public void onPageFinished(WebView view, String url)
{
backButton = findViewById(R.id.backButton);
backButton.setEnabled(blizzView.canGoBack());
if (blizzView.canGoBack()) {
backButton.setVisibility(View.VISIBLE);
} else {
backButton.setVisibility(View.INVISIBLE);
}
}
You can use WebView#canGoBack to find out if there is a backstack. You can check for that after the page is loaded e.g. in WebViewClient#onPageFinished
It works like this:
blizzView.setWebViewClient(new WebViewClient() { //
#Override
public void onPageFinished(WebView view, String url) {
super.onPageFinished(view, url);
backButton = findViewById(R.id.backButton);
backButton.setEnabled(blizzView.canGoBack());
if (blizzView.canGoBack()) {
backButton.setVisibility(View.VISIBLE);
} else {
backButton.setVisibility(View.INVISIBLE);
}
}
});
so I have a working webview that is simple, but most of the work is done in the main activity. I am trying to break it out to its own little class so I can load other classes into the main activity on the fly. I am stuck on how to do this. I have tried this a few times and been debugging it but I just dont know if I am using the right findByValue(R.id.webView); thing here. it keeps giving me a
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.webkit.WebView.findViewById(int)' on a null object reference
issue. I have tried passing the reference in as a parameter and also hard coded it. I am missing something but dont know what. There is a WebView in my activity_main that is called wevView that is what I am trying to find out where i'm did mistake.
Thanks for any help with this.
So this is my webview class:
public class NewWebView {
//variables need for webview
private final String myPage = "http://www.google.com";
WebView myWebView = null;
//consturctor
public NewWebView(){}
//This method creates the WebView
public void createWebView(WebView webView)
{
//WebView code
//Find the Webview in the Activity.xml file
//myWebView = webView;
myWebView = (WebView)myWebView.findViewById(R.id.webview);
// myWebView = (android.webkit.WebView)findViewById(R.id.webview);
//Use the custom WebViewClient for internal app browsing
myWebView.setWebViewClient(new MyWebViewClient());
//now for enabling the settings
WebSettings webSettings = myWebView.getSettings();
//Enable JavaScript
webSettings.setJavaScriptEnabled(true);
//Enable andriod zoom features
webSettings.setBuiltInZoomControls(true);
//Loading the Url
myWebView.loadUrl(myPage);
}
//Methods Used for WebViewer
//custom WebViewClent needed for internal app navigatiion
private class MyWebViewClient extends WebViewClient
{
public boolean shouldOverRideUrlLoading(android.webkit.WebView view, String url)
{
if(Uri.parse(url).getHost().equals(myPage))
{
//this is Apivita remain in the APP
return false;
}
/*
//if it is not in my site redirect it to mobile browers
Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
startActivity(intent);
return true;
*/
return true;
}
}
//Enable the use of the system back button for navigation
public boolean onKeyDown(int keyCode, KeyEvent event)
{
//if the back button was pushed
if((keyCode == KeyEvent.KEYCODE_BACK) && myWebView.canGoBack())
{
myWebView.goBack();
return true;
}
//if not
return false;
}
}
and here is the main activity
public class MainActivity extends AppCompatActivity {
WebView myWebView = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//create the webview
myWebView = (android.webkit.WebView)findViewById(R.id.webview);
NewWebView apWebView = new NewWebView();
apWebView.createWebView(myWebView);
}
}
It looks like you are finding your webview in the main activity and then passing it into your class. In your custom class, you're then trying to find another view, which you technically already have. So its trying to find a webview, inside of the webview. It obviously can't find this, so it's null.
In theory, you should be able to just use myWebView = webView;, however, you need to make sure that it is finding it in the first place.
I use this code to check if a user touched inside a webview
webview.setOnTouchListener(new View.OnTouchListener()
{
public boolean onTouch(View v, MotionEvent event)
{
if(event.getAction() == MotionEvent.ACTION_UP)
{
//action
}
return false;
}
});
but I will need to do action only if user clicked (touched ) a link only ,not if the the user touch some pictures or do a scrool in webview.
I need to reinit some variables when new webpage is loaded ,or when a user clicks on a link , but not when he click random on screen or he do scrool.
i can not use
public void onPageStarted(WebView view, String url, Bitmap favicon)
or
public boolean shouldOverrideUrlLoading(WebView view, String url)
cause this are called multiple times while a page is loaded and I only need to do action first time only 1 time , when user click on a link (or button or something that make webview to load a new page)
Does anybody knwo how to do this?
Thank you in advance
first step - enable JavaScript:
WebView myWebView = (WebView) findViewById(R.id.webview);
WebSettings webSettings = myWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
second step - create interface between Java and Javascript:
public class WebAppInterface {
Context mContext;
/** Instantiate the interface and set the context */
WebAppInterface(Context c) {
mContext = c;
}
/** Show a toast from the web page */
#JavascriptInterface
public void showToast(String toast) {
Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
}
}
register your interface:
webView.addJavascriptInterface(new WebAppInterface(this), "Android");
and put this JS in your html page:
<script type="text/javascript">
function showAndroidToast(toast) {
Android.showToast(toast);
}
</script>
example for html:
<input type="button" value="Say hello" onClick="showAndroidToast('Hello Android!')" />
if pages which you are showing are not your you might download them as plain text, then insert JS and load html with myWebView.loadDataWithBaseURL. this way you have full control of which user is clicking and what to do with it
to be honest I don't understand why you cannot do this with shouldOverrideUrlLoading(WebView view, String url) by checking what is arriving in url String and setting 'consumed' flag or smth like this
also: whole code is stolen from HERE
I have a simple webview that loads a website. Once the website is loaded, I have the following to focus/scroll to the login box:
mWebview.setWebViewClient(new WebViewClient(){
#Override
public void onPageFinished(WebView view, String url) {
// TODO Auto-generated method stub
super.onPageFinished(view, url);
mWebview.scrollTo(681, 100);
(I've heard that onPageFinished is deprecated, but it's working for me in 2.2>4.4, so I'm just leaving it for now.
Anyway, I would like some sort of way to monitor for when the user actually logs in, that way when the page is done loading for the second time, I can then call some js and forward them to another page, but I have no idea how to do that. :(
I can just do another onPageFinished after they log in, but I don't know how to start monitoring... In other words, I can't start another onPageFinished immediately after the current, because it just redirects automatically.
Does anyone have any suggestions? I would greatly appreciate it! :)
EDIT:
Here's the entirety (minus the import headers) of my MainActivity.java class.
public class MainActivity extends Activity {
private WebView mWebview ;
#Override
public void onBackPressed() {
if(mWebview.canGoBack() == true){
mWebview.goBack();
}else{
super.onBackPressed();
}
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mWebview = new WebView(this);
mWebview.getSettings().setJavaScriptEnabled(true); // enable javascript
mWebview.getSettings().setBuiltInZoomControls(true);
if(android.os.Build.VERSION.SDK_INT >= 11) {
mWebview.getSettings().setDisplayZoomControls(false);
}
final Activity activity = this;
mWebview.setWebViewClient(new WebViewClient() {
public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
Toast.makeText(activity, description, Toast.LENGTH_SHORT).show();
}
});
mWebview .loadUrl("http://example.com");
setContentView(mWebview );
mWebview.setWebViewClient(new WebViewClient(){
#Override
public void onPageFinished(WebView view, String url) {
// TODO Auto-generated method stub
super.onPageFinished(view, url);
mWebview.scrollTo(681, 100);
}
}
);
}
I think I might be missing a curly bracket, but ignore that for now, haha. So anyway, after mWebview.scrollTo (the last line), the webpage is done loading, and it just chills at the login page. After a user logs in, the page (obviously) starts to load and directs to another post-login URL. I'd like to check the URL with an if statement after the page is done loading for the second time.
Does that make more sense? Sorry, it's confusing me too, trying to explain it.
Usually there will be two separate URLs, one for the post log-in page and one for the pre log-in page. You can have an if statement that checks the URL to make sure you've logged in, and if you have, then it redirects/closes/whatever.
I had a similar issue here:
Closing a Webview in Android
So basically you just want to execute some JavaScript once you've logged in? I don't see why you can't have an if statement to check whether you're logged in or not, and if you're logged in, then execute the js.
Something like this maybe?
wv.setWebViewClient(new WebViewClient() {
#Override
public void onPageFinished(WebView view, String url) {
if (url.contains(getString(R.string.loginURL))){
super.onPageFinished(view, url);
mWebview.scrollTo(681, 100);
}else if(url.contains(getString(R.string.loggedInURL))) {
wv.loadUrl(js goes here);
}
}
}
This will execute every time a page is finished loading in your WebView
I have been trying to put a back button progress bar in a webview and keep the url loading within my app instead of using the android default web browser.
If I manage to keep to browsing within the app and keep the back button the progress bar never shows up if I manage to get the progress bar to show up the code at the bottom for shouldoverideurl come up never read and the default browser launches, I tried all the google tutorials and solution but none of them work. I am currently using google.. Can anyone help??
public class livebrad extends Activity {
WebView mWebView;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// Adds Progrss bar Support
this.getWindow().requestFeature(Window.FEATURE_PROGRESS);
setContentView(R.layout.brows);
// Makes Progress bar Visible
getWindow().setFeatureInt( Window.FEATURE_PROGRESS, Window.PROGRESS_VISIBILITY_ON);
// Get Web view
mWebView = (WebView) findViewById( R.id.webView ); //This is the id you gave
//to the WebView in the main.xml
mWebView.getSettings().setJavaScriptEnabled(true);
mWebView.getSettings().setSupportZoom(true); //Zoom Control on web (You don't need this
//if ROM supports Multi-Touch
mWebView.getSettings().setBuiltInZoomControls(true); //Enable Multitouch if supported by ROM
// Load URL
mWebView.loadUrl("http://www.bbc.co.uk");
// Sets the Chrome Client, and defines the onProgressChanged
// This makes the Progress bar be updated.
final Activity MyActivity = this;
mWebView.setWebChromeClient(new WebChromeClient() {
public void onProgressChanged(WebView view, int progress)
{
//Make the bar disappear after URL is loaded, and changes string to Loading...
MyActivity.setTitle("Loading...");
MyActivity.setProgress(progress * 100); //Make the bar disappear after URL is loaded
// Return the app name after finish loading
if(progress == 100)
MyActivity.setTitle(R.string.app_name);
}class HelloWebViewClient extends WebViewClient {
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
}
});
}//End of Method onCreate
}
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class SandbarinFacebook extends Activity {
WebView mWebView;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fb);
final ProgressDialog pd = ProgressDialog.show(this, "", "Loading...",
true);
mWebView = (WebView) findViewById(R.id.webkitWebView1);
mWebView.getSettings().setJavaScriptEnabled(true);
mWebView.getSettings().setSupportZoom(true);
mWebView.getSettings().setBuiltInZoomControls(true);
mWebView.setWebViewClient(new WebViewClient() {
#Override
public void onPageFinished(WebView view, String url) {
if(pd.isShowing() && pd!=null)
{
pd.dismiss();
}
}
});
mWebView.loadUrl("http://m.facebook.com/sandbarathens");
}
}
If you want show progress bar each time user clicks links, add code to show progressbar in your shouldOverrideUrlLoading() method.
You just missed this statement.
mWebView.setWebViewClient(..)