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I'm using HTML5 AppCache to create an Android web app which can function offline. HTML which sources additional images, stylesheets, javascript and iframes is loaded into a WebView with loadDataWithBaseURL(). Unfortunately, when the device is offline only the HTML sourced in iframes is loaded from AppCache.
At this point, I know:
Here's some demo code:
public class ExampleActivity extends Activity {
...
// HTML to be inserted into the Webview with loadDataWithBaseURL()
public static final String ALL_HTML =
"<!DOCTYPE HTML><html>" +
"<head><script src='sourced_js.js' " +
"onload='console.log(\"sourced_js.js onload\");'>" +
"</script>" +
"<link rel='stylesheet' href='style.css' />" + // doesn't load offline
"</head><body>" +
"<iframe src='manifest.html'></iframe>" + // loads
"<img src='android.jpg' />" + // doesn't load
"<img src='android.gif' />" + // doesn't load
"</body></html>";
public void onCreate(Bundle savedInstanceState) {
...
WebView webView = new WebView(context);
webView.clearCache(true);
WebSettings settings = webView.getSettings();
settings.setAppCacheEnabled(true);
settings.setJavaScriptEnabled(true);
webView.loadDataWithBaseURL("http://my.website.com/path/to/content/",
ALL_HTML, "text/html", "utf-8", null);
}
}
manifest.html is just responsible for referencing the manifest. It looks like:
<html manifest="manifest.appcache">
<head></head>
<body></body>
</html>
manifest.appcache looks like:
CACHE MANIFEST
# Explicitly cached resources
# manifest.html automatically cached
sourced_js.js
android.jpg
android.gif
style.css
NETWORK:
*
When online, all content loads. When offline, only the iframe with manifest.html loads. The images, stylesheet and javascript are not loaded.
Strangely enough, if I source the exact same static content (sourced_js.js, android.jpg, ...) in manifest.html, they all load from AppCache in the iframe properly when the device is offline! As if these other resources have to be sourced secondarily from a static page.
Any clue why this content won't be loaded from the AppCache?
762
asked Apr 22 '26 02:04
The appcache should not work if you don't set the correct MIME type response setting (text/cache-manifest) for *.appcache files in your web server, according to the specs.
The same behavior is expected in desktop browsers, mobile browsers and iOS UIWebView.
165
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