Android. WebView and loadData

Solution 1:

myWebView.loadData(myHtmlString, "text/html; charset=UTF-8", null);

This works flawlessly, especially on Android 4.0, which apparently ignores character encoding inside HTML.

Tested on 2.3 and 4.0.3.

In fact, I have no idea about what other values besides "base64" does the last parameter take. Some Google examples put null in there.

Solution 2:

WebView.loadData() is not working properly at all. What I had to do was:

String header = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>";
myWebView.loadData(header+myHtmlString, "text/html", "UTF-8");

I think in your case you should replace UTF-8 with latin1 or ISO-8859-1 both in header and in WebView.loadData().

And, to give a full answer, here is the official list of encodings: http://www.iana.org/assignments/character-sets

I update my answer to be more inclusive:

To use WebView.loadData() with non latin1 encodings you have to encode html content. Previous example was not correctly working in Android 4+, so I have modified it to look as follows:

WebSettings settings = myWebView.getSettings();
settings.setDefaultTextEncodingName("utf-8");
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) {
    String base64 = Base64.encodeToString(htmlString.getBytes(), Base64.DEFAULT);
    myWebView.loadData(base64, "text/html; charset=utf-8", "base64");
} else {
    String header = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>";
    myWebView.loadData(header + htmlString, "text/html; charset=UTF-8", null);

}

But later I have switched to WebView.loadDataWithBaseURL() and the code became very clean and not depending on Android version:

WebSettings settings = myWebView.getSettings();
settings.setDefaultTextEncodingName("utf-8");
myWebView.loadDataWithBaseURL(null, htmlString, "text/html", "utf-8", null);

For some reason these functions have completely different implementation.

Solution 3:

As I understand it, loadData() simply generates a data: URL with the data provide it.

Read the javadocs for loadData():

If the value of the encoding parameter is 'base64', then the data must be encoded as base64. Otherwise, the data must use ASCII encoding for octets inside the range of safe URL characters and use the standard %xx hex encoding of URLs for octets outside that range. For example, '#', '%', '\', '?' should be replaced by %23, %25, %27, %3f respectively.

The 'data' scheme URL formed by this method uses the default US-ASCII charset. If you need need to set a different charset, you should form a 'data' scheme URL which explicitly specifies a charset parameter in the mediatype portion of the URL and call loadUrl(String) instead. Note that the charset obtained from the mediatype portion of a data URL always overrides that specified in the HTML or XML document itself.

Therefore, you should either use US-ASCII and escape any special characters yourself, or just encode everything using Base64. The following should work, assuming you use UTF-8 (I haven't tested this with latin1):

String data = ...;  // the html data
String base64 = android.util.Base64.encodeToString(data.getBytes("UTF-8"), android.util.Base64.DEFAULT);
webView.loadData(base64, "text/html; charset=utf-8", "base64");