从互联网检索数据

Question

The following code is from my first internet app. I have not tested it because there is no WLAN available for me. What I want to do next is to retrieve data from the website.

Is there any procedure to follow to achieve such task?

JAVA Code:

public class Internet00 extends Activity {

TextView tv00;
public boolean isNetworkAvailable() {
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netWorkinfo = cm.getActiveNetworkInfo();

    if (netWorkinfo != null && netWorkinfo.isConnected()) {
        return true;
    }
    return false;
}
private void readStream(InputStream in) {
    BufferedReader reader = null;
    try {
        reader = new BufferedReader(new InputStreamReader (in));
        String line="";
        while ( (line=reader.readLine()) != null)
            tv00.setText(line);
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (reader != null) {
          try {
            reader.close();
          } catch (IOException e) {
            e.printStackTrace();
            }
        }
    }
}
@SuppressLint({ "ParserError", "NewApi" })
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_internet00);

    tv00 = (TextView) findViewById(R.id.tv00);
    if(isNetworkAvailable()) {
        StrictMode.ThreadPolicy policy = new StrictMode.
            ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);

    try {
          URL url = new URL("http://www.vogella.com");
          HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
          readStream(con.getInputStream());
        } catch (Exception e) {
          e.printStackTrace();
           }
        }
    }
}

Answer 1

Could you be a little more specific?

It looks to me like you're retrieving the data already.

Your code should fail, because of you're doing network stuff in the UI Thread.

Answer 2

Yes of-course, you need to follow some rules.

1. Please don't use network thread in UI thread
2. Use AsyncTask for download related works

A working example can be found here : Getting info from api using JSON

Refer my answer in above post to download data from a server to your device. This working example can be a good start for you.