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Do you want to make a webview browser?

Don’t worry, I will help you to make a simple one.

Just like this.

simple browser - android webview example - progressbar included - download source code
simple browser – android webview example – progressbar included – download source code



Download Source Code – Kotlin & Java

In this post, you will learn more about WebView. Okay, let’s start…

What is Android WebView?

There may be occasions when you want to show a webpage to your users such as Terms and conditions, app manual or your website and so on.

In a traditional way, we can send users to an external web browser but there is no guarantee that users would come back. So that’s one of the main reasons Android introduced a widget named WebView.

As the name suggests it helps to show or view online and offline web pages in our app. It’s available in android.webkit package and has abilities in history management, zooming, javascript, and CSS rendering.

So you can load the webpage easily in your app,  webview will take care of it. It’s not a browser because it lacks navigational toolbar like features.

From the beginning to now, WebView has grown a lot. Let’s check how it implemented in Android.

WebView to Android System Webview – implementation history

WebView to Android System WebView -WebView implementation history
WebView to Android System WebView -WebView implementation history
WebView was added in API level 1. It renders web pages using Webkit engine, which behind Apple’s Safari browser. Actually, WebKit makes an environment or views for the webpage to display on the app.

In Android 4.4, For better performance, Google decided to change webview rendering from stock webview to google’s chromium or blink.

Lots of bugs and fixes through os update, that made long time vulnerable. So Android engineers innovated a separate Android System Webview app that can install and update through Google’s app market Play store with next release “Lolipop”.

That made easy fixes in less time.

In Android 7.0, there is no need to enable Android System Webview app, Chrome will take care of webview. if it is disabled or uninstalled already, the system will use android system webview.

If both of them get disabled, webview will use stock Webkit engine and take care of your valuable web pages.

How to add WebView to your layout?

Webview can easily be added in your layout as any other view. You can just drag and drop webview or write code for that just like below

You can use it as a root element or as a child element. While using as a root element don’t forget to add XML namespace.

How To Create WebView Programmatically In Android?

What is layout in Android?

For Kotlin users, I am using Android studio 3.1.2 and it uses Kotlin Android Extensions plugin by default.  So there is no need to call findviewByid and cast. just use the id of the widget and call the methods.

Make sure Android Studio has imported these lines

Okay… Let’s start with our first example – Using the loadUrl() method.

Android WebView loadUrl() example

android webview loadurl example
android webview loadurl example

We can easily load a webpage in webview using loadUrl() method. Just put your URL as a string, Before that, we must provide Internet permission in AndroidManifest.xml.

create a webview app in android with below code


android system webview version
android system webview version

If you are testing webview code in devices which contains Android System WebView version below 43.0.2357.121 or below Lolipop. If anyone below happens

  1. server side redirect
  2. Click on links in WebView

Then it might lead to opening an external browser. To force open all links in WebView, we need to set WebViewClient.


This is enough to open your links in webview. It internally calls, shouldOverrideUrlLoading() method and it returns false. False means redirect or clicking on a link opens in the same webview, True will abort the operation.

How to open link in the external browser using Android WebView

Sometimes You need to open your website links in webview and other links in external browsers. Then you can use the below sample code.

replace “www.example.com” with your site name.


But shouldOverrideUrlLoading (WebView view, String url) was deprecated in API level 24. So if you are planning to make an application for Nougat or above, then you can use

public boolean shouldOverrideUrlLoading (WebView view,WebResourceRequest request)

To open links in WebView in All devices use both shouldOverrideUrlLoading() methods just like

How To Play YouTube Video In WebView By Enabling JavaScript In Android

Let’s open youtube in our webview.

Use our first example, and replace URL in loadUrl with “https://www.youtube.com” and run.

You may see these type of actions:

  1. Youtube shows a progress bar loading.
  2. Bowser says Please enable JavaScript in your browser.

This is because of JavaScript. If you are a web developer, you already know the importance of javascript. If you don’t, Javascript is a client-side programming language, it helps us to provide validation, animations and popups and so on.

By default, Javascript is disabled on your browser. we can easily enable it by simple lines of code.

how to enable javascript in android webview
how to enable javascript in android webview

Now you can start watching youtube videos in your webview.

Android WebView local file example

android webview local file example
android webview local file example

In this example, you will learn how to show a local HTML file in webview. We have already created a webpage for you. You can use that for a sample.

Just make an assets folder in your project, Right click on app->New->Folder->Assets Folder. Now a dialog appears to change the location of assets folder. Leave it and Click Finish.

Place demo.html into assets folder and use below code

loadUrl() uses

LoadUrl() is a broad method and it works with:

  1. http:// and https:// URLs.
  2. Eg: webview.loadUrl(“https://www.androidride.com”)
    Webview.loadUrl(“//www.androidride.com”)

  3. Local filesystem URLs.
  4. Eg: webview.loadUrl(“file:///storage/sdcard/index.html”)

    Don’t forget to add

    In your AndroidManifest.xml.

  5. Application assets and resources URLs.
  6. eg:Webview.loadUrl(“file:///android_asset/demo.html”)

    In URL, use android_asset not android_assets, yes, there is no ‘s’ at the end.

    webview.loadUrl(“file:///android_res/mipmap/ic_launcher”)
    There is no need for the file extension, but it won’t be a problem if you add it.

  7. content://URLs pointing content provider.
  8. ERR_UNKNOWN_URL_SCHEME in Android WebView – Fixed.

    err_unknown_url_scheme in android webview fixed
    err_unknown_url_scheme in android webview fixed

    In this example, You will learn how to solve ERR_UNKNOWN_URL_SCHEME in Android WebView. This type of error happens when WebView deals with UNKNOWN URL SCHEME links. Before that learn some basics.

    What is URL SHEME?

    The URL scheme is something before the colon in the URL. actually, it’s the protocol describes how to access the resource.

    Scheme://host:port?path
    eg: https://www.androidride.com:80/webview.html

    WebView knows how to deal with HTTP, HTTPS, and file Schemes, but they don’t know what to do when these type of schemes come. ‘tel:’, ‘sms:’, and ‘mailto:’ and others.

    So we have to tell webview to how to deal with those schemes in shouldOverrideUrlLoading() method. In this example, we are going to use ‘tel:’, ‘sms:’, ‘mailto:’, and ‘geo:’ links. When you click on them, each link will get opened with appropriate apps installed on your Android device.

    demo.html

    • If it’s a network URL, WebView force the links to open in WebView,otherwise find a best option from Android System.

    Create your webview app with the above code or you can download our example.

    WebView loadData() example in Android

    In this Android WebView example, we will show you how to render HTML code in Android WebView. It’s simple, Android API provides a method called loadData().

    loadData() method needs 3 contents.

    1. String htmlData: This is our html content.
    2. String mimeType: here we use “text/html”.
    3. String encoding: most of the time, base64 or UTF-8.
    • It works with data,http and https schemes.
    • If you use other schemes, webview can’t access content due to javascript same origin policy.
    • You should use loadDataWithBaseURL(), if you want to use other schemes.


    webview loaddata example in android
    webview loaddata example in android

    WebView loadDataWithBaseURL() example in Android

    In this example, you will learn how to work with loadDataWithBaseURL() example. When you want to fetch an image from the assets folder using loadData() method. JavaScript origin policy restricts the access to content.

    loadDataWithBaseURL() avoids this problem by specifying BaseURL. Using the Base URL, system resolve relative URLs in HTML content.

    loadDataWithBaseURL() needs

    1. String baseURL: This URL is used to resolve relatvie URLs.
    2. String data: Html content that you want to show.
    3. String mimeType: mimeType of HTML data
    4. String encoding: encoding of html data
    5. String historyURL: This URL loads when you navigate back in webview

    In this example, I am going to use the same loadData() code but just want to add image ‘ic_launcher’ from the mipmap folder.

    android webview loaddatawithbaseurl example
    android webview loaddatawithbaseurl example

    Android WebView Download File example

    android webview download file example
    android webview download file example

    In this android webview example, you will learn how to download a file using WebView and DownloadManager. Using DownloadManager, we can reduce code and leave the stress to DownloadManager. We also show AlertDialog for Download notification.

    You can download the file using AsyncTask too.

    Create a webview app project in Android Studio, Add below lines to AndroidManifest.xml

    Use below code


    How To Run JavScript In Android WebView

    how to run javascript in android webview
    how to run javascript in android webview

    I already said JavaScript has an important role in the web world. In Android, we can also make use of JavaScript by sending data to Javascript from Android and vice versa. But it also raises security issues too. If you are using any third-party code, make sure it’s not vulnerable to users security.

    Android API provides a number of methods and classes to achieve a super web app. I have categorized them

    JavaScript calling Kotlin/Java

    1. addJavascriptInterface()
    2. WebMessagePort – (6.0)

    Kotlin/Java calling JavaScript

    1. loadUrl()
    2. evaluateJavascript() – (4.4)
    3. WebMessage – (6.0)

    The numbers shown in the brackets means the starting API. We are not going to discuss WebMessagePort and WebMessage here. That will be updated later.

    webview addJavascriptInterface example in android

    webview addjavascriptinterface example in android
    webview addjavascriptinterface example in android

    In this addJavascriptInterface example, we send a message from a local HTML webpage to Android and show it through a toast.

    JavaScript can access methods in API level Build.VERSION_CODES.JELLY_BEAN_MR1 and above, if they are

    • defined as public
    • annotated with JavascriptInterface

    sample.html

    MainActivity.kt


    how above code works?

    • JavaScript enabled.
    • Inject java object into webpage using addJavascriptInterface() method. It needs
      1. Java class object: The java class object which inject into webview
      2. String name: The name used to access java methods from JavaScript
      3. It’s better to remove java object from webview after the use

    WebView evaluateJavascript example in Android

    evaluatejavascript android webview example
    evaluatejavascript android webview example

    Let’s call javascript from Java. In this example, we receive the text from edittext and send it to the local HTML page. Use loadUrl() for below 4.4 and evaluateJavascript() works with KitKat and above.

    sample.html

    MainActivity.kt


    Simple WebView Browser example – Progress bar included

    Finally, we are here. Let’s create a webview app browser. This browser has

    • ProgressBar support
    • Google search and load URL support
    • Download file support
    • YouTube video support
    • Navigate history and custom home page
    • Share Support

    open your Android Studio.

    Step 1

    Start a new Android Studio project.

    Application Name: WebView Browser
    Company Domain: androidride.example.com

    Check Include Kotlin Support.


    Step 2

    Select form factors and minimum SDK

    Select API 15: IceCreamSandwich and Click Next.


    Step 3

    Add Empty activity to Project.


    Step 4

    Add INTERNET and WRITE_EXTERNAL_STORAGE permission in AndroidManifest.xml

    AndroidManifest.xml

    • android:windowSoftInputMode=”stateAlwaysHidden|adjustNothing” – it helps by without adjusting our bottom bar layout and disable the focus in EditText while startup.

    Step 5

    build.gradle


    Step 6

    Colors.xml

    Step 7

    Styles.xml

    Step 8

    activity_main.xml

    • android:layout_weight attribute used to hold widgets.
    • android:inputType=”textNoSuggestions” disable spell check
    • android:background=”?android:selectableItemBackground” – makes transparent

    I have used vector asset icons, you can also access them by right clicking on res->New->Vector Asset->Click on clip Art and select your icons, you can change color and size. Click OK and Next.


    Step 9

    custom_progress.xml


    Step 10

    This browser has a simple home page, for that, we have to add local HTML file in the assets folder.

    demo.html


    Step 11

    MainActivity.kt


    Hey… Thanks for scrolling. If you find anything useful in this post, please share it.

    Conclusion

    WebView has an important role in Android programming. With a few lines of code, beginners can also easily load web pages in their app. You have learned to download the file and run javascript using Android WebView. I am sure that these examples make you better dealing with WebView. This is a small guide about WebView. You can also find more information from below links.