Android：异步任务，HTTP处理程序服务器关闭？

Question

在我的程序通过HTTP处理程序检查登录部分。但是，如果服务器关闭HTTP处理程序出错。我可以检查HTTP处理程序makeServiceCall()方法是成功还是失败？

public class LoginActivity extends AppCompatActivity { 

    private EditText et_Username; 
    private EditText et_Password; 
    private String st_Username; 
    private String st_Password; 
    private boolean checkCustomer = false; 
    private ProgressDialog pDialog; 
    private String url; 
    private BroadcastReceiver broadcastReceiver = null; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_login); 

     Thread.setDefaultUncaughtExceptionHandler (new Thread.UncaughtExceptionHandler() 
     { 
      @Override 
      public void uncaughtException (Thread thread, Throwable e) { 
       handleUncaughtException (thread, e); 
      } 
     }); 
    } 

    public void OnLogin(View view){ 
     st_Username = et_Username.getText().toString(); 
     st_Password = et_Password.getText().toString(); 
     if(st_Password.isEmpty() || st_Username.isEmpty()){ 
      showToast("Fill all!!!"); 
     } else { 
      if (!isNetworkAvailable(this)) { 
       AlertDialog.Builder builder = new AlertDialog.Builder(this); 
       builder.setTitle(R.string.no_network_connection_title); 
       builder.setMessage(R.string.no_network_connection_message) 
         .setCancelable(false) 
         .setPositiveButton("OK", new DialogInterface.OnClickListener() { 
          public void onClick(DialogInterface dialog, int id) { 
          } 
         }); 
       AlertDialog alert = builder.create(); 
       alert.show(); 
      } else executeAsyncTask(); 
     } 
    } 

    public void executeAsyncTask() { 
     AsyncTask<Void, Void, Void> task = new AsyncTask<Void, Void, Void>() { 

      String jsonStr; 
      @Override 
      protected void onPreExecute() { 
       super.onPreExecute(); 

       pDialog = new ProgressDialog(LoginActivity.this); 
       pDialog.setMessage("Please wait..."); 
       pDialog.setCancelable(false); 
       pDialog.show(); 
      } 

      @Override 
      protected Void doInBackground(Void... params) { 
       HttpHandler sh = new HttpHandler(); 
       url = "myUrl"; 
       // Making a request to url and getting response 
       String[] st_Username_array = st_Username.split(" "); 
       String[] st_Password_array = st_Password.split(" "); 
       if (st_Password_array.length > 1 || st_Username_array.length > 1) { 
        checkCustomer = false; 
       } else { 
        url += st_Username; 

        url += "/"+st_Password; 
        jsonStr = sh.makeServiceCall(url); 

        if(jsonStr.trim().equals("No")){ 
          checkCustomer = false; 
         } else { 
         JSONObject jsonObj = null; 
         try { 
       get jsonObject and send data 
           sh2.makeServiceCall(senddataUrl); 
          } 

          checkCustomer = true; 

         } catch (JSONException e) { 
          e.printStackTrace(); 
         } 
        } 
       } 
       return null; 
      } 

      @Override 
      protected void onPostExecute(Void msg) { 
       Log.v("AsyncTask", "onPostExecute in Login"); 

       if (pDialog.isShowing()){ 
        pDialog.dismiss(); 
        if(checkCustomer){ 

         Intent intent = new Intent(LoginActivity.this, ThirdActivity.class); 
         startActivity(intent); 
         finish(); 
        } else { 
         showToast("Your user name or password is wrong!"); 
         et_Password.setText(""); 
        } 
       } 
      } 
     }; 

     if(Build.VERSION.SDK_INT >= 11/*HONEYCOMB*/) { 
      task.executeOnExecutor(Executors.newSingleThreadExecutor()); 
     } else { 
      task.execute(); 
     } 
    } 

    public static boolean isNetworkAvailable(Context c) { 
     ConnectivityManager cm = (ConnectivityManager) c.getSystemService(Context.CONNECTIVITY_SERVICE); 
     NetworkInfo networkInfo = cm.getActiveNetworkInfo(); 

     if (networkInfo != null && networkInfo.isConnected()) { 
      return true; 
     } 
     return false; 
    } 

    public void handleUncaughtException (Thread thread, Throwable e) { 
     e.printStackTrace(); // not all Android versions will print the stack trace automatically 

     Intent intent = new Intent (this, LoginActivity.class); 
     showToast(e.toString()); 
     startActivity (intent); 
     System.exit(1); // kill off the crashed app 
    } 
} 

Answer 1

使用此代码查看您的服务器是否正在响应请求。您可以使用服务器的hostname或IP。

try { 
      SocketAddress sockaddr = new InetSocketAddress(ip, port); 
    //  SocketAddress sockaddr = new InetSocketAddress(String hostname, int port) 
      Socket sock = new Socket(); 

//   int timeoutMs = 1000; 
//   sock.connect(sockaddr, timeoutMs) 

      sock.connect(sockaddr); 
      exists = true; 

      sock.close(); 

     } catch (Exception e) { 
      e.printStackTrace(); 
     }