连接本地主机时出错

Question

我知道这个问题已经被多次询问过，但现在我很无奈。

我有一个PHP网页在localhost回显“你好”。 （在localhost上完美工作）。 我有下面的代码显示从我的应用程序本地主机网页到TextView的响应。

tv = (TextView) findViewById(R.id.txtTest); 
InputStream is = null; 
String result = ""; 
    String url = "http://10.0.2.2/android/try.php"; 
    HttpClient httpclient = new DefaultHttpClient(); 

    try {    
     HttpPost httppost = new HttpPost(url); 

     HttpResponse response = httpclient.execute(httppost); 

     Log.d("myapp", "response " + response.getEntity()); 

     HttpEntity entity = response.getEntity(); 
     is = entity.getContent(); 
     String st = EntityUtils.toString(response.getEntity()); 


    } catch (Exception e) { 
     Log.e("log_tag", "Error in http connection " + e.toString()); 
    } 

    // convert response to string 
    try { 
     BufferedReader reader = new BufferedReader(new InputStreamReader(
       is, "UTF-8"), 8); 
     StringBuilder sb = new StringBuilder(); 
     String line = null; 
     while ((line = reader.readLine()) != null) { 
      sb.append(line + "\n"); 
     } 
     is.close(); 
     result = sb.toString(); 
    } catch (Exception e) { 
     Log.e("log_tag", "Error converting result " + e.toString()); 
    } 

    tv.setText(result.toString()); 

我得到以下错误（LogCat）。

09-24 13:34:42.654: E/log_tag(2032): Error in http connection android.os.NetworkOnMainThreadException 
09-24 13:34:42.654: E/log_tag(2032): Error converting result java.lang.NullPointerException 

P.S我已经在清单中添加Internet权限。

Answer 1

您应该从主（UI）线程以外的线程执行网络操作（连接等）。这就是你所得到的错误android.os.NetworkOnMainThreadException。

你应该看看ASyncTask或Thread来做到这一点。

阅读this article太...

这个替换您当前拥有的代码：

AsyncTask<Void,Void,Void> my_task = new AsyncTask<Void,Void,Void>() { 
     @Override 
     protected void onPostExecute() { 
      TextView tv = (TextView) findViewById(R.id.txtTest); 
      tv.setText(result.toString()); 
     } 

     @Override 
     protected Void doInBackground(Void... voids) { 
      InputStream is = null; 
      String result = ""; 
      String url = "http://10.0.2.2/android/try.php"; 
      HttpClient httpclient = new DefaultHttpClient(); 

      try { 
       HttpPost httppost = new HttpPost(url); 

       HttpResponse response = httpclient.execute(httppost); 

       Log.d("myapp", "response " + response.getEntity()); 

       HttpEntity entity = response.getEntity(); 
       is = entity.getContent(); 
       String st = EntityUtils.toString(response.getEntity()); 


      } catch (Exception e) { 
       Log.e("log_tag", "Error in http connection " + e.toString()); 
      } 

      // convert response to string 
      try { 
       BufferedReader reader = new BufferedReader(new InputStreamReader(
         is, "UTF-8"), 8); 
       StringBuilder sb = new StringBuilder(); 
       String line = null; 
       while ((line = reader.readLine()) != null) { 
        sb.append(line + "\n"); 
       } 
       is.close(); 
       result = sb.toString(); 
      } catch (Exception e) { 
       Log.e("log_tag", "Error converting result " + e.toString()); 
      } 
     } 
    }.execute();