android 从webview中读取缓存的图片

SQLiteDatabase db = getActivity().openOrCreateDatabase("webviewCache.db", Context.MODE_PRIVATE, null);
Cursor c = db.rawQuery("SELECT * FROM cache where url = ?",new String[]{iImageUrl});
while (c.moveToNext()) {
    String filepath= c.getString(c.getColumnIndex("filepath"));
    File file=new File(getActivity().getCacheDir()+"/webviewCache/"+filepath);
    FileInputStream inStream=new FileInputStream(file);
    drawable=BitmapFactory.decodeStream(inStream);
}

c.close();

后来测试HUAWEI Y320-T00发现它没有生成webviewCache.db，倒是有webviewCookiesChromiun.db和webviewCookiesChromiunPrivate.db

用sqlite3进去里面查看表，发现找不到cache这个表，也没有保存url的连接和文件路径，这个方法有问题