使用HttpConnection时出错

Question

QUESTION

I am trying to parse an XML file from a website. I am using an HTTP connection for getting the XML content from the website. While I am downloading the content I am facing some issues. The code is given below.

CODE

public class MainActivity extends AppCompatActivity {
Button button;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button= (Button) findViewById(R.id.button);

}
public void process(View view)  {
    Thread thread=new Thread(new Download());
    thread.start();



}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
public class Download implements Runnable {
    public void run() {
        try {
            URL url = new URL("http://api.androidhive.info/pizza/?format=xml");
            HttpURLConnection connection= (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.getDoOutput();
            InputStream stream = connection.getInputStream();
            Toast.makeText(MainActivity.this, stream + "", Toast.LENGTH_LONG).show();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
} }

This is the code I am using to download the content. The error I am getting is

ERROR

10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ java.net.UnknownHostException: Unable to resolve host "api.androidhive.info": No address associated with hostname
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at java.net.InetAddress.lookupHostByName(InetAddress.java:424)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at java.net.InetAddress.getAllByName(InetAddress.java:214)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpEngine.connect(HttpEngine.java:311)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:282)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:177)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at com.example.sajithm.domparsing.MainActivity$Download.run(MainActivity.java:65)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at java.lang.Thread.run(Thread.java:841)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ Caused by: libcore.io.GaiException: getaddrinfo failed: EAI_NODATA (No address associated with hostname)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.io.Posix.getaddrinfo(Native Method)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at libcore.io.ForwardingOs.getaddrinfo(ForwardingOs.java:61)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ at java.net.InetAddress.lookupHostByName(InetAddress.java:405)
10-21 01:14:21.459  25125-25181/com.example.sajithm.domparsing W/System.err﹕ ... 15 more
    --------- beginning of /dev/log/system
10-21 01:19:34.259  25125-25131/com.example.sajithm.domparsing D/dalvikvm﹕ GC_FOR_ALLOC freed 306K, 4% free 9003K/9336K, paused 5ms, total 5ms

REQUEST The web address is valid. Can anyone please suggest a solution to tackle this problem. Is there any other way to download the content?

Answer 1

I have tried below code and it worked :

Method to make a call :

 public void makeXMLRequest() {
        try {
            URL url = new URL("http://api.androidhive.info/pizza/?format=xml");
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            con.setRequestMethod("GET");
            con.getDoOutput();
            String readStream = readStream(con.getInputStream());
            // Give output for the command line
            System.out.println(readStream);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

Reference method to parse response :

 private static String readStream(InputStream in) {
        StringBuilder sb = new StringBuilder();
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(in));) {

            String nextLine = "";
            while ((nextLine = reader.readLine()) != null) {
                sb.append(nextLine);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return sb.toString();
    }

How to call this method :

 Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                makeXMLRequest();
            }
        });

        thread.start();

Try this if it can help.

Thanks..!

Answer 2

Though you can access the website by web browser of your computer. I can access the link as well. But it doesn't mean your Android phone can resolve the domain name. Please use adb shell to try

ping api.androidhive.info

You will most probably see a negative response.

Answer 3

This is a problem with emulator. In some cases emulator cannot access websites though the site is accessible through our pc browser. I reinstalled the virtual device (In my case it was Nexus 4.3) inside Genymotion,now everything works fine and the emulator is capable to access all websites.

Thank you