在android中使用webview将CSS注入到网站

例如,我想将www.google.com的背景颜色更改为red 。 我已经使用webview ,而我的style.css文件是在assest folder 。 我想将这个style.css文件注入www.google.com 。 我的代码有什么问题? 请为我写正确的代码。 谢谢。 我的MainActitviy.java文件:

 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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你不能直接注入CSS,但是你可以使用Javascript来操作页面。

 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); } }