例外情況：當用戶發佈評論時，沒有路由到主機發送到服務器

Question

這種情況很少發生，我無法重現它，但下面的代碼有時會從無主機獲取異常。這裏是代碼：

public class AddComment extends AsyncTask<String, Void, String> 
{ 
    @Override 
    protected String doInBackground(String... theParams) 
    { 
     String myUrl = theParams[0]; 
     final String comment = theParams[1]; 
     final String user_id = theParams[2]; 
     final String problem_id = theParams[3]; 
     final String recent_topic_id = theParams[4]; 

     String charset = "UTF-8";   
     String response = null; 

     try 
     {       
      String query = String.format("comment=%s&user_id=%s&problem_id=%s&recent_topic_id=%s", 
        URLEncoder.encode(comment, charset), 
        URLEncoder.encode(user_id, charset), 
        URLEncoder.encode(problem_id, charset), 
        URLEncoder.encode(recent_topic_id, charset) 
        );    

      final URL url = new URL(myUrl + "?" + query); 

      final HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 

      conn.setDoOutput(true); 
      conn.setRequestMethod("POST"); 

      conn.setDoOutput(true); 
      conn.setUseCaches(false); 

      conn.connect(); 

      InputStream stream = conn.getInputStream(); 
      byte[] stream_buffer = new byte[8196]; 
      int readCount; 
      StringBuilder stream_builder = new StringBuilder(); 
      while ((readCount = stream.read(stream_buffer)) > -1) 
      { 
       stream_builder.append(new String(stream_buffer, 0, readCount)); 
      } 

      response = stream_builder.toString();  
     } 
     catch (Exception e) 
     { 
          // EXCEPTION HAPPENS HERE 
       e.printStackTrace(); 
     } 

     return response; 
    } 

    @Override 
    protected void onPostExecute(String result) 
    { 
      if (result == null) 
      { 
        // Do stuff 
      } 
     } 
     else 
     {    
     // Do stuff 
    }   
}   

有人會知道爲什麼會發生這種情況，以及如何防止它？

Answer 1

你是在物理設備上測試這個嗎？這可能是由於電池信號不良，或者如果您的設備或模擬器的互聯網連接不穩定造成的。這也可以解釋爲什麼你不能重現它。