Question

当我运行我的应用程序时，它总是给我＆＃34;无效的ip＆＃34;，无法从数据库中获取数据。我是新手，所以我对android不太了解。我从谷歌

获取此代码

以下是我的代码段，请帮帮我。

    public class EnterGeneralDetails extends Activity {

    InputStream is=null;
    String result=null;
    String line=null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_general_details);

        try
        {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://thecapitalcitychurch.16mb.com/new/CohortName.php");
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();
            Log.e("Pass 1", "connection success ");
        }
        catch(Exception e)
        {
            Log.e("Fail 1", e.toString());
            Toast.makeText(getApplicationContext(), "Invalid IP Address",
                    Toast.LENGTH_LONG).show();
        }

        try
        {
            BufferedReader reader = new BufferedReader
                    (new InputStreamReader(is,"iso-8859-1"),8);

            StringBuilder sb = new StringBuilder();

            while ((line = reader.readLine()) != null)
            {
                sb.append(line + "\n");
            }

            is.close();
            result = sb.toString();
            Log.e("Pass 2", "connection success ");
        }
        catch(Exception e)
        {
            Log.e("Fail 2", e.toString());
        }

        try
        {
            JSONArray JA=new JSONArray(result);
            JSONObject json= null;
            final String[] str1 = new String[JA.length()];
            final String[] str2 = new String[JA.length()];

            for(int i=0;i<JA.length();i++)
            {
                json=JA.getJSONObject(i);
                str1[i] = json.getString("ID");
                str2[i]=json.getString("Cohort_Name");
            }

            final Spinner sp = (Spinner) findViewById(R.id.spinner22);
            List<String> list = new ArrayList<String>();

            for(int i=0;i<str2.length;i++)
            {
                list.add(str2[i]);
            }


            Collections.sort(list);

            ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>
                    (getApplicationContext(), android.R.layout.simple_spinner_item, list);
            dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            sp.setAdapter(dataAdapter);

            sp.setOnItemSelectedListener(new OnItemSelectedListener()
            {
                public void onItemSelected(AdapterView<?> arg0, View arg1,int position, long id)
                {
                    // TODO Auto-generated method stub

                    String item=sp.getSelectedItem().toString();

                    Toast.makeText(getApplicationContext(), item,
                            Toast.LENGTH_LONG).show();

                    Log.e("Item",item);
                }

                public void onNothingSelected(AdapterView<?> arg0)
                {
                    // TODO Auto-generated method stub
                }
            });
        }
        catch(Exception e)
        {
            Log.e("Fail 3", e.toString());
        }
    }

}

PHP代码

<?php
    $DB_USER='u868549735_rj';
    $DB_PASS='myself00';
    $DB_HOST='mysql.hostinger.in';
    $DB_NAME='u868549735_db';
    $mysqli = new mysqli($DB_HOST, $DB_USER, $DB_PASS, $DB_NAME);
    /* check connection */
    if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
    }       

    $mysqli->query("SET NAMES 'utf8'");
    $sql="SELECT ID, Cohort_Name FROM Cohorts";
    $result=$mysqli->query($sql);
    while($e=mysqli_fetch_array($result)){
    $output[]=$e;
    }   

    print(json_encode($output));
    $mysqli->close();   

    ?>

Answer 1

据我所知，你有一个NetworkOnMainThreadException。当您尝试在主线程上执行任何网络操作时，会发生这种情况。

当应用程序尝试在其主线程上执行网络操作时引发的异常。

仅针对Honeycomb SDK或更高版本的应用程序进行此操作。针对早期SDK版本的应用程序可以在其主要事件循环线程上进行网络连接，但是非常不鼓励这样做。请参阅文档设计响应性。

要解决此问题，请查看AsyncTask。

private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
     protected Long doInBackground(URL... urls) {
         int count = urls.length;
         long totalSize = 0;
         for (int i = 0; i < count; i++) {
             totalSize += Downloader.downloadFile(urls[i]);
             publishProgress((int) ((i / (float) count) * 100));
             // Escape early if cancel() is called
             if (isCancelled()) break;
         }
         return totalSize;
     }

     protected void onProgressUpdate(Integer... progress) {
         setProgressPercent(progress[0]);
     }

     protected void onPostExecute(Long result) {
         showDialog("Downloaded " + result + " bytes");
     }
 }

创建后，任务执行非常简单：

new DownloadFilesTask().execute(url1, url2, url3);

PS：使用Log.e("Fail 1", e.toString());被认为是不好的做法。请改用e.printStackTrace（）。

无法从数据库中获取数据？

1 个答案: