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For example I want to change the background-color of www.google.comto red. I have used webview, and my style.cssfile is in assest folder. I want to inject this style.css file to www.google.com. What is wrong with my codes? Please write the correct codes for me. Thanks. My MainActitviy.java file :
package com.example.mysina; import android.support.v7.app.ActionBarActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.webkit.WebView; public class MainActivity extends ActionBarActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); WebView webView = new WebView(this); setContentView(webView); String html = "<html><head><style> src: url('file:///android_asset/style.css')</style></head></html>"; webView.loadData(html, "text/html", "utf-8"); webView.loadUrl("https://www.google.com"); } @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); } } 
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Double-click the “src” folder in your Android project. Double-click the package containing the WebView Activity then double-click the Activity to open it in the editor. Click inside the “onCreate” method to begin typing there.
Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project. Step 2 − Add the following code to res/layout/activity_main. xml. In the above code, we have taken web view to show html content.
Yes you can, you can use javascript to get webpage content. Then use the webview jsInterface to return the content to you java code.
By default this is set to true and the WebView accepts cookies.
You can't inject CSS directly however you can use Javascript to manipulate page dom.
public class MainActivity extends ActionBarActivity { WebView webView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); webView = new WebView(this); setContentView(webView); // Enable Javascript webView.getSettings().setJavaScriptEnabled(true); // Add a WebViewClient webView.setWebViewClient(new WebViewClient() { @Override public void onPageFinished(WebView view, String url) { // Inject CSS when page is done loading injectCSS(); super.onPageFinished(view, url); } }); // Load a webpage webView.loadUrl("https://www.google.com"); } // Inject CSS method: read style.css from assets folder // Append stylesheet to document head private void injectCSS() { try { InputStream inputStream = getAssets().open("style.css"); byte[] buffer = new byte[inputStream.available()]; inputStream.read(buffer); inputStream.close(); String encoded = Base64.encodeToString(buffer, Base64.NO_WRAP); webView.loadUrl("javascript:(function() {" + "var parent = document.getElementsByTagName('head').item(0);" + "var style = document.createElement('style');" + "style.type = 'text/css';" + // Tell the browser to BASE64-decode the string into your script !!! "style.innerHTML = window.atob('" + encoded + "');" + "parent.appendChild(style)" + "})()"); } catch (Exception e) { e.printStackTrace(); } } @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); } } I was able to inject css by using "evaluateJavascript" which was added to WebView in API 19 https://developer.android.com/reference/android/webkit/WebView
Example in Kotlin:
private lateinit var webView: WebView override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) //... webView = findViewById(R.id.your_webview_name) webView.settings.javaScriptEnabled = true webView.webViewClient = object : WebViewClient() { override fun onPageFinished(view: WebView, url: String) { val css = ".menu_height{height:35px;}.. etc..." //your css as String val js = "var style = document.createElement('style'); style.innerHTML = '$css'; document.head.appendChild(style);" webView.evaluateJavascript(js,null) super.onPageFinished(view, url) } } webView.loadUrl("https://mywepage.com") //webpage you want to load } UPDATE: The code above had issues applying all of the injected CSS. After consulting with my web developer, we decided to inject the link to the CSS file instead of the CSS code itself. I changed the values of the css and js variables ->
val css = "https://mywebsite.com/css/custom_app_styles.css" val js = "var link = document.createElement('link'); link.setAttribute('href','$css'); link.setAttribute('rel', 'stylesheet'); link.setAttribute('type','text/css'); document.head.appendChild(link);" If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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