DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);

switch (metrics.densityDpi) {
case DisplayMetrics.DENSITY_HIGH:
    webView.getSettings().setDefaultZoom(WebSettings.ZoomDensity.FAR);
    break;

case DisplayMetrics.DENSITY_MEDIUM:
    webView.getSettings().setDefaultZoom(WebSettings.ZoomDensity.MEDIUM);
    break;

case DisplayMetrics.DENSITY_LOW:
    webView.getSettings().setDefaultZoom(WebSettings.ZoomDensity.CLOSE);
    break;

default:
    webView.getSettings().setDefaultZoom(WebSettings.ZoomDensity.MEDIUM);
    break;
}