Question

我有一个简单的Android应用程序，它使用jSoup从URL获取数据。我和TOAST有一个肮脏的解决方案给我一个在线或离线的警告。我希望能够获得用户上次在用户离线时查询存储的新信息的数据。我不知道从哪里开始？我读过有关Data Cache，SQLite等的内容......

从jsoup解析中存储数据的最佳方法是什么，以便在用户离线时检索它？

到目前为止，这是我的代码：

public class SlockActivity extends SherlockActivity {
    private TextView textView;
    private String url = "http://www.backcountryskiers.com/sac/sac-full.html";
    private String noDangerUrl = "http://www.sierraavalanchecenter.org/sites/default/files/images/danger_icons_and_bars/0_nodangerrate.png";
    private ImageView image;
    private TextView tvWX;

    // GLOBAL RESOURCES
    private static SlockActivity instance = null;

    // private ProgressDialog dialog = new ProgressDialog(SlockActivity.this);

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        menu.add("Emergency")
                .setIcon(R.drawable.emergencyicon)
                .setShowAsAction(
                        MenuItem.SHOW_AS_ACTION_IF_ROOM
                                | MenuItem.SHOW_AS_ACTION_WITH_TEXT);
        menu.add("Weather")
                .setIcon(R.drawable.wx_icon)
                .setShowAsAction(
                        MenuItem.SHOW_AS_ACTION_IF_ROOM
                                | MenuItem.SHOW_AS_ACTION_WITH_TEXT);
        menu.add("Refresh")
                .setIcon(R.drawable.ic_refresh)
                .setShowAsAction(
                        MenuItem.SHOW_AS_ACTION_IF_ROOM
                                | MenuItem.SHOW_AS_ACTION_WITH_TEXT);

        return true;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.todaysReport);
        image = (ImageView) findViewById(R.id.dangerRose);
        tvWX = (TextView) findViewById(R.id.todaysWX);

        boolean check = isOnline();
        if (check == true) {
            Toast.makeText(this, "Internet is Connected", Toast.LENGTH_LONG)
                    .show();
            fetcher task = new fetcher();
            task.execute();
        }

        else {

            Toast.makeText(this, "Failed to connect to internet.",
                    Toast.LENGTH_LONG).show();
            textView.setText("No Network Connection and attempt to get Cached Data did not work. ");
        }

    }

    public static Bitmap getBitmapFromURL(String src) {
        try {
            Log.e("src", src);
            URL url = new URL(src);
            HttpURLConnection connection = (HttpURLConnection) url
                    .openConnection();
            connection.setDoInput(true);
            connection.connect();
            InputStream input = connection.getInputStream();
            Bitmap myBitmap = BitmapFactory.decodeStream(input);
            Log.e("Bitmap", "returned");
            return myBitmap;
        } catch (IOException e) {
            e.printStackTrace();
            Log.e("Exception", e.getMessage());
            return null;
        }

    }

    class fetcher extends AsyncTask<String, Void, String> {
        // HERE DECLARE THE VARIABLES YOU USE FOR PARSING
        private ProgressDialog dialog = new ProgressDialog(SlockActivity.this);
        private Document doc = null;
        private Elements content = null;
        private Document parse = null;
        private String results = null;
        private Element dangerRatingImg = null;
        private String dangerRatingSrc = null;
        private Bitmap bimage;

        @Override
        protected String doInBackground(String... params) {
            try {
                doc = Jsoup.connect(url).get();
                Log.e("Jsoup", "...is working...");
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e("Exception", e.getMessage());
            }

            content = doc.select("#content");
            parse = Jsoup.parse(doc.html());
            results = doc.select("#content").outerHtml();

            // find rating image...
            dangerRatingImg = doc.select("img").first();
            dangerRatingSrc = dangerRatingImg.absUrl("src");
            // Get the rating image
            bimage = getBitmapFromURL(dangerRatingSrc);

            return results;
        }

        @Override
        protected void onPostExecute(String result) {
            dialog.dismiss();
            // smooth out the long scrolling...
            textView.setMovementMethod(ScrollingMovementMethod.getInstance());
            // Set this after the load so the background is the picture without
            // the textviews background in
            textView.setBackgroundResource(R.drawable.tvbg);
            // Set the rating image
            //
            // DO THE IMAGE REPLACE ON URL COMPARE THING HERE>>>>>>>
            if (dangerRatingSrc.equals(noDangerUrl)) {
                image.setImageDrawable(getResources().getDrawable(
                        R.drawable.nodanger));
            }
            //
            // image.setImageBitmap(bimage);
            image.setPadding(0, 10, 0, 30);
            // image.setScaleType(ScaleType.FIT_XY);

            // return the summary
            results = parse.select("#reportSummary").outerHtml();
            // String reportDate = parse.select("#reportDate").outerHtml();
            textView.setText(Html.fromHtml(results));
            // textView.append(Html.fromHtml("<a href='#'><em>Read Full Report &raquo;</em></a>"));
            textView.setPadding(30, 20, 20, 10);
            // ditch the dialog, it's all loaded.
            tvWX.setText(Html.fromHtml("Today's High: <b>26F</b>"));
        }

        @Override
        protected void onPreExecute() {
            // before we get the async results show this
            dialog.setMessage("Loading Latest Update from the Sierra Avalanche Center...");
            dialog.show();
        }

    }

    // check network connectivity
    public boolean isOnline() {
        ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo netInfo = cm.getActiveNetworkInfo();
        if (netInfo != null && netInfo.isConnectedOrConnecting()) {
            Log.i("Network", "IS CONNECTED");
            return true;
        }
        Log.i("Network", "IS NOT-CONNECTED");
        return false;
    }

    public void onClickFullReport(View v) {
        Intent intentFullReport = new Intent(getBaseContext(),
                FullReportActivity.class);
        intentFullReport.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
        startActivity(intentFullReport);
    }
}

Answer 1

我建议将String写入文件中只能读取的文件，如文档中所述：http://developer.android.com/guide/topics/data/data-storage.html#filesInternal

将“data”写入文件“filename.txt”：

String FILENAME = "filename.txt";
String string = "data";

FileOutputStream fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
fos.write(string.getBytes());
fos.close();

再次阅读：

FileInputStream fis = context.openFileInput(FILENAME);
StringBuffer fileContent = new StringBuffer("");

byte[] buffer = new byte[1024];
int length;
while ((length = fis.read(buffer)) != -1) {
    fileContent.append(new String(buffer));
}
String string = fileContent.toString();

如果用户离线，我应该在sqlite中存储数据吗？

1 个答案: