18-1. 네트워크

※ HttpURLConnection

 - url을 통해 데이터를 읽어온다.

 - 메인스레드가 아닌 별도의 스레드를 만들어 그 부분에서 데이터 다운로드가 작동되도록 한다.

   메인스레드에서는 사용자와의 교감을 지속적으로 해줘야함.  

 - URL 객체를 만들고 URL Connection을 만들어 인터넷에 연결한다. 

 - Stream을 통하여 이미지, 문자열을 받아온다.

MainActivity

public class MainActivity extends Activity {

      

      String urlAddr = "http://www.sba.seoul.kr";

      Button btn;

      

      @Override

      protected void onCreate(Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);

            setContentView(R.layout.activity_main);   

            

            btn = (Button) findViewById(R.id.button1);

            btn.setOnClickListener(onclick);

      }

      

      OnClickListener onclick = new OnClickListener() {

            

            @Override

            public void onClick(View v) {

                  // TODO Auto-generated method stub

                  NetWorkAsyncTask netWorkAsyncTask = new NetWorkAsyncTask(MainActivity.this,urlAddr );

                  netWorkAsyncTask.execute(100);

                  

            }

      };

      

}

NetWorkAsyncTask

public class NetWorkAsyncTask extends AsyncTask<Integer, String, Integer>{

      Context mContext = null;

      String mAddr;

      ProgressDialog dialog = null;

      

      public NetWorkAsyncTask(Context context, String addr){

            mContext = context;

            mAddr = addr;

      }

      

      @Override

      protected void onPreExecute() {

            dialog = new ProgressDialog(mContext);

            dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);

            dialog.setTitle("Dialog");

            dialog.setMessage("Down");

            dialog.show();

      }

      

      @Override

      protected Integer doInBackground(Integer... params) {

            // TODO Auto-generated method stub

            

            StringBuffer sb = new StringBuffer();

            InputStream is = null;

            InputStreamReader isr = null;

            BufferedReader br = null;

            

            try {

                  //url 객체 생성

                  URL url = new URL(mAddr);

                  //커낵션 객체 구하기

                  HttpURLConnection connection = (HttpURLConnection) url.openConnection();

                  //커낵션 객체가 url에 접속하는데 기다리는 시간, 10초동안 접속이 안되면 exception으로 넘어감

                  connection.setConnectTimeout(10000);

                  

                  //if문 조건 - http로 통신이 되는 상태를 나타낸다.

                  if(connection.getResponseCode() == HttpURLConnection.HTTP_OK){

                        is = connection.getInputStream();

                        isr = new InputStreamReader(is);

                        br = new BufferedReader(isr);

                        

                        while(true){

                              String strLine = br.readLine();

                              if(strLine == null){

                                    break;

                              }

                              sb.append(strLine + "\n");

                        }

                        

                        //sb에 저장된 텍스트를 처리한다.

                  }

                  

            } catch (Exception e) {

                  // TODO: handle exception

                  e.printStackTrace();

            }

            return null;

      }

      

      

      @Override

      protected void onProgressUpdate(String... values) {

            // TODO Auto-generated method stub

            super.onProgressUpdate(values);

      }

      

      @Override

      protected void onPostExecute(Integer result) {

            // TODO Auto-generated method stub

            dialog.dismiss();

      }

      

      @Override

      protected void onCancelled() {

            // TODO Auto-generated method stub

            super.onCancelled();

      }

}

※