webview can't access local files?

Hello everyone!
I tried to use webview to load local html file
(for convenience, I modified sample project ApiDemos ./development/samples/ApiDemos/src/com/example/android/apis/view/WebView1.java)

@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.webview_1);
final String mimeType = "text/html";
final String encoding = "utf-8";
WebView wv;
try {
InputStream is = getAssets().open("HelloWorld.html"
int size = is.available();
// Read the entire asset into a local byte buffer.
byte[] buffer = new byte[size];
is.read(buffer);
is.close();
// Convert the buffer into a string.
String strContent = new String(buffer);

wv = (WebView) findViewById(R.id.wv1);
wv.loadData(strContent, mimeType, encoding);
} catch (IOException e) {
// Should never happen!
throw new RuntimeException(e);
}
}

HelloWorld.html & HelloWorld.css is saved in folder : ./ApiDemos/assets

@import "HelloWorld.css";

Hello, World!

After startup the emulator, I pushed default.png in to folder /data/data/com.example.android.apis/,

But when I run ApiDemos->View->WebView, the image does not show up, and here is the information in log:
D/WebCore ( 216): Console: Not allowed to load local resource: file:///data/data/com.example.android.apis/default.png line: 0 source:

So, what's the proplem?