android - 我不知道如何解决(android.os.networkonmainthreadexception)

Question

我总是得到这个错误

   public class FlightAvailabityGoActivity extends ListActivity {
String[] monthName = {"Jan", "Feb",
          "Mar", "Apr", "May", "Jun", "Jul",
          "Aug", "Sep", "Oct", "Nov",
          "Dec"
          };


date userDate=new date();
int DepDay=userDate.getDays();
int DepMonth=userDate.getMonths();

bean beanz=new bean();
private TextView fromToTextView;
Calendar calendar = new GregorianCalendar();
  String am_pm;
  String TAG="from";
  private TextView from,to;
  languages lang=new languages();
  String En_Ar=lang.getLang();
  Element dest;

  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {

    try{
    Log.v(TAG, "in go activity       " +TAG);

    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
    setContentView(R.layout.listplaceholder_flightavailabity);
    if(En_Ar.equals("arabic"))
    {
    getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.window_title_flightavailabity_ar);
   // from=(TextView)findViewById(R.id.fromText);
   // from.setText("  من  ");
   // to=(TextView)findViewById(R.id.toText);
    //to.setText("  إلى  ");
    Log.v(TAG, "1       " +TAG);
    }
    else
    {
          Log.v(TAG, "1       " +TAG);
    getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE,  
     R.layout.window_title_flightavailabity);
    }






    ////
    Bundle extras = getIntent().getExtras();

    String FromCity = extras.getString("from");
    String ToCity = extras.getString("to");
    Log.v(TAG, "from city after moving   " +FromCity);
    Log.v(TAG, "to city after moving   " +ToCity);






    ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
    ArrayList<HashMap<String, String>> mylist1 = new ArrayList<HashMap<String, String>>();

    Log.v(TAG, "2       " +TAG);
    //String xml = XMLfunctions.getXMLFlightAva(FromCity,ToCity);
    String xml=XMLfunctions.getXMLFlightAva(FromCity,ToCity);  // error is here
    Log.v(TAG, "3      " +TAG);  // this will not display
    xml=xml.trim();
    Log.v(TAG, "4       " +TAG);

我对此很生气，我理解它关于使用互联网的问题，但我不知道如何解决它？如您所见，我在我的 XML 函数类中通过 HTTP get 读取 XML，它在此处以字符串形式返回 XML，这里所有的东西都崩溃了

我必须改变类(class)吗 String xml=XMLfunctions.getXMLFlightInfo(FromCity);

同样的方法

          String xml=XMLfunctions.getXMLFlightAva(FromCity,ToCity);

这是类(class)

             public class XMLfunctions {
             String TAG;



public final static Document XMLfromString(String xml){


    Document doc = null;

    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {

        DocumentBuilder db = dbf.newDocumentBuilder();

        InputSource is = new InputSource();
        is.setCharacterStream(new StringReader(xml));
        doc = db.parse(is); 

    } catch (ParserConfigurationException e) {
        System.out.println("XML parse error: " + e.getMessage());
        return null;
    } catch (SAXException e) {
        System.out.println("Wrong XML file structure: " + e.getMessage());
        return null;
    } catch (IOException e) {
        System.out.println("I/O exeption: " + e.getMessage());
        return null;
    }

    return doc;

}

/** Returns element value
  * @param elem element (it is XML tag)
  * @return Element value otherwise empty String
  */
 public final static String getElementValue( Node elem ) {
     Node kid;
     if( elem != null){
         if (elem.hasChildNodes()){
             for( kid = elem.getFirstChild(); kid != null; kid = kid.getNextSibling() ){
                 if( kid.getNodeType() == Node.TEXT_NODE  ){
                     return kid.getNodeValue();
                 }
             }
         }
     }
     return "";
 }
 ////////////////////////
 public static String getXMLFlightInfo(String Y_or_T){   
        String line = null;
        String TAG="TAG";
        date userDate=new date();
        int DepDay=userDate.getDays();
        int DepMonth=userDate.getMonths();



        try {

            DefaultHttpClient httpClient = new DefaultHttpClient();
        //  HttpPost httpPost = new HttpPost("http://p-xr.com/xml");
            //HttpGet httpPost=new HttpGet("http://10.128.11.206:9080/mobile/FlightSchdIphoneServlet?depCity="+fromCity+"&arrCity="+toCity+"&day="+DepDay+"&month="+DepMonth+"");
            //HttpGet httpPost=new HttpGet("http://mysv.net.sa/Web/mobile/FlightAvailIphoneServlet?depCity=JED&arrCity=RUH&day=29&month=11&submit=+GO+");
            HttpGet httpPost=new HttpGet("http://10.131.13.43:9080/onlineSMS/xmlFlightInfo.html");

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            line = EntityUtils.toString(httpEntity);



        } catch (UnsupportedEncodingException e) {
            line = "<array status=\"error\"><msg>Can't connect to server</msg></array>";
        } catch (MalformedURLException e) {
            line = "<array status=\"error\"><msg>Can't connect to server</msg></array>";
        } catch (IOException e) {
            line = "<array status=\"error\"><msg>Can't connect to server</msg></array>";
        }

        return line;

}

Answer 1

StrictMode.ThreadPolicy从 API 级别 9 开始引入，默认行为在 API 级别 11 中已更改，简而言之，不允许网络操作(包括 HttpClient 和 HttpUrlConnection)在 UI 线程上执行。

正确的策略是将网络操作移出 UI 线程，例如使用 AsyncTask .

希望这对您有所帮助。