Intercept and override HTTP requests from WebView

Try this, I've used it in a personal wiki-like app:

webView.setWebViewClient(new WebViewClient() {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if (url.startsWith("foo://")) {
            // magic
            return true;
        }
        return false;
    }
});

It looks like API level 11 has support for what you need. See WebViewClient.shouldInterceptRequest().

As far as I know, shouldOverrideUrlLoading is not called for images but rather for hyperlinks... I think the appropriate method is

@Override public void onLoadResource(WebView view, String url)

This method is called for every resource (image, styleesheet, script) that's loaded by the webview, but since it's a void, I haven't found a way to change that url and replace it so that it loads a local resource ...