Question

以下代码无法连接到SQLite。

public class MainActivity extends ListActivity {

    JSONArray jArray; String result = null; InputStream is = null;
    StringBuilder sb=null;

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

        ArrayList<NameValuePair> nameValuePairs = new
        ArrayList<NameValuePair>(); //http post
        try{
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://xxx.xxx.xxx.xxx/");
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();
        }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,"iso-8859-1"),8);
            sb = new StringBuilder();
            sb.append(reader.readLine() + "n");

            String line="0";
            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());
        } //paring data
        int Ravid_id;
        String Ravid_Name;
        try{
            jArray = new JSONArray(result);
            JSONObject json_data=null;
            for(int i=0;i<jArray.length();i++){
                json_data = jArray.getJSONObject(i);
                Ravid_id=json_data.getInt("Ravid_id");
                Ravid_Name=json_data.getString("Ravid_Name");
            }
        } catch(JSONException e1){
            Toast.makeText(getBaseContext(), "No found" ,Toast.LENGTH_LONG).show();
        } catch (ParseException e1) {
            e1.printStackTrace();
        }
    }
}

Answer 1

这只是猜测并且与经常发布的问题有关：您不应该在主线程上执行任何网络操作。这段代码......

HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://xxx.xxx.xxx.xxx/");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();

...应放在AsncTask或Service中。有关如何解决此问题的示例（通常为android.os.NetworkOnMainThreadException），请参阅this post。

Android应用程序错误与我的代码

1 个答案: