Как отправить httppost в android с помощью AsyncTask?

Question

Я пытаюсь использовать httppost для хранения данных в базе данных. Я узнал, что попытка сделать это в основном потоке вызвала сбой, поэтому я пытаюсь использовать AsyncTask.

это AsyncTask код, который я создал

public class PostData extends AsyncTask<String, Void, String> { 

    protected String doInBackground(String... params){ 
     // get zero index of nameValuePairs and use that to post 
     String result = "fail"; 
     try{ 
      HttpClient httpclient = new DefaultHttpClient(); 
      HttpPost httppost = new HttpPost("http://www.name.com/Script.php"); 


      // Add your data 
      List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2); 
      Log.d("1", "nope"); 
      nameValuePairs.add(new BasicNameValuePair("id", params[0])); 
      Log.d("2", "nope"); 
      httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); 
      Log.d("3", "nope"); 

      // Execute HTTP Post Request 
      HttpResponse response = httpclient.execute(httppost); 
      Log.d("4", "nope"); 
      Log.i("postData", response.getStatusLine().toString()); 
      result="got it"; 
     } 
     catch (Exception e){ 
      Log.d("lol","lool"); 
     } 
     finally{} 

     return result; 

    } 
} 

Я только начал андроид недавно, так что я совершенно не знаком с AsyncTask. вот код, где им пытаются использовать этот класс

public class HomePage extends ActionBarActivity { 

    PostData postD; 

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

    //Connect to other activities 

    public void aboutPage(View view) throws IOException { 
     //Intent intent = new Intent(this, AboutPage.class); 
     //startActivity(intent); 

     postD.doInBackground("1111"); 



    } 

, и новый чат Ошибка при получении

01-30 18:13:44.592 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/art﹕ Not late-enabling -Xcheck:jni (already on) 
01-30 18:13:44.962 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/OpenGLRenderer﹕ Render dirty regions requested: true 
01-30 18:13:45.003 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/﹕ HostConnection::get() New Host Connection established 0xa6853600, tid 1921 
01-30 18:13:45.033 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/Atlas﹕ Validating map... 
01-30 18:13:45.110 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/﹕ HostConnection::get() New Host Connection established 0xa6853740, tid 1942 
01-30 18:13:45.130 1921-1942/com.example.user2013.mobileapplicationcustomerversion I/OpenGLRenderer﹕ Initialized EGL, version 1.4 
01-30 18:13:45.169 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/OpenGLRenderer﹕ Enabling debug mode 0 
01-30 18:13:45.216 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/EGL_emulation﹕ eglSurfaceAttrib not implemented 
01-30 18:13:45.216 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6805440, error=EGL_SUCCESS 
01-30 18:13:48.461 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Choreographer﹕ Skipped 78 frames! The application may be doing too much work on its main thread. 
01-30 18:13:49.128 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/EGL_emulation﹕ eglSurfaceAttrib not implemented 
01-30 18:13:49.128 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6805440, error=EGL_SUCCESS 
01-30 18:13:49.828 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Choreographer﹕ Skipped 36 frames! The application may be doing too much work on its main thread. 
01-30 18:13:51.004 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/AndroidRuntime﹕ Shutting down VM 
    --------- beginning of crash 
01-30 18:13:51.004 1921-1921/com.example.user2013.mobileapplicationcustomerversion E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    Process: com.example.user2013.mobileapplicationcustomerversion, PID: 1921 
    java.lang.IllegalStateException: Could not execute method of the activity 
      at android.view.View$1.onClick(View.java:4007) 
      at android.view.View.performClick(View.java:4756) 
      at android.view.View$PerformClick.run(View.java:19749) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5221) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
    Caused by: java.lang.reflect.InvocationTargetException 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at android.view.View$1.onClick(View.java:4002) 
      at android.view.View.performClick(View.java:4756) 
      at android.view.View$PerformClick.run(View.java:19749) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5221) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method \'java.lang.String com.example.user2013.mobileapplicationcustomerversion.PostData.doInBackground(java.lang.String[])\' on a null object reference 
      at com.example.user2013.mobileapplicationcustomerversion.HomePage.aboutPage(HomePage.java:41) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at android.view.View$1.onClick(View.java:4002) 
      at android.view.View.performClick(View.java:4756) 
      at android.view.View$PerformClick.run(View.java:19749) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5221) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
01-30 18:14:00.311 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Process﹕ Sending signal. PID: 1921 SIG: 9 

Answer 1

здесь:

postD.doInBackground("1111"); 

Вы вызываете doInBackground метод с использованием объекта класса, который также будет работать на главной теме.

Чтобы запустить doInBackground в фоновом режиме, вам необходимо запустить AsyncTask с помощью метода AsyncTask.execute. сделать это так:

public void aboutPage(View view) throws IOException { 
    postD=new PostData(); 
    postD.execute("1111"); 
} 

Подробнее о AsyncTask