Android的填充內容從一個ListView在數據庫

Question

我有這樣的Android活動代碼：

package com.problemio; 

import java.io.InputStream; 
import java.net.Authenticator; 
import java.net.HttpURLConnection; 
import java.net.PasswordAuthentication; 
import java.net.URL; 
import java.net.URLEncoder; 
import java.util.List; 

import org.json.JSONArray; 
import org.json.JSONObject; 

import com.problemio.LoginActivity.DownloadWebPageTask; 

import android.app.Activity; 
import android.app.ListActivity; 
import android.content.Intent; 
import android.content.SharedPreferences; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.preference.PreferenceManager; 
import android.util.Log; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 
import android.widget.TextView; 
import android.widget.Toast; 

public class MyProblemsActivity extends ListActivity 
{ 
    static final String[] COUNTRIES = new String[] {}; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     //setContentView(R.layout.problem); 

     setListAdapter(new ArrayAdapter<String>(this, R.layout.my_problems, COUNTRIES)); 

     ListView lv = getListView(); 
     lv.setTextFilterEnabled(true); 

     lv.setOnItemClickListener(new OnItemClickListener() 
     { 
      public void onItemClick(AdapterView<?> parent, View view, 
       int position, long id) 
      { 
       // When clicked, show a toast with the TextView text 
       Toast.makeText(getApplicationContext(), ((TextView) view).getText(), 
        Toast.LENGTH_SHORT).show(); 

       // For now just do something simple like display a responsive message 
       Log.d("MyProblemsActivity" , "A choice was made from the list"); 
      } 
      });   

     // Check if person is logged in 
     SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(MyProblemsActivity.this); 
     final String user_id = prefs.getString("user_id" , null); 

     // If the user is not logged in, send them to log in 
     if (user_id == null) 
     { 
      Intent loginIntent = new Intent(MyProblemsActivity.this, LoginActivity.class); 
      MyProblemsActivity.this.startActivity(loginIntent);   
     }   

     // Go to the database and display a list of problems, all clickable. 
     sendFeedback(user_id); 
    } 

    public void sendFeedback(String user_id) 
    { 
     Log.d("user_id in MyProblemsActivity" , user_id); 

     String[] params = new String[] { "http://www.problemio.com/problems/get_users_problems_mobile.php", user_id }; 

     DownloadWebPageTask task = new DownloadWebPageTask(); 
     task.execute(params);   
    }    


    public void onItemClick(AdapterView<?> items, View v, int x, long y) 
    { 
     Log.d("onItemClick: " , "In the onItemClick method of MyProblemsActivity"); 

    } 

    public class DownloadWebPageTask extends AsyncTask<String, Void, String> 
    { 
     @Override 
     protected String doInBackground(String... theParams) 
     { 
      Log.d("MyProblemsActivity" , "in doInBackground method."); 

      String myUrl = theParams[0]; 
      final String user_id = theParams[1]; 

      Log.d("Inner myURL: " , myUrl); 
      Log.d("user_id: " , user_id); 

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

      try 
      {    
       String query = String.format("user_id=%s", 
         URLEncoder.encode(user_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(); 

       final InputStream is = conn.getInputStream(); 
       final byte[] buffer = new byte[8196]; 
       int readCount; 
       final StringBuilder builder = new StringBuilder(); 
       while ((readCount = is.read(buffer)) > -1) 
       { 
        builder.append(new String(buffer, 0, readCount)); 
       } 

       response = builder.toString();  
       Log.d("After call, response: " , " " + response); 
      } 
      catch (Exception e) 
      { 
        Log.d("Exception: " , "Yup"); 
        e.printStackTrace(); 
      } 

      return response; 
     } 

     @Override 
     protected void onPostExecute(String result) 
     { 
      Log.d("Post execute: " , "In the post-execute method: " + result); 
      //textView.setText(result); 

      if (result != null && result == "no_such_user") 
      { 
       Log.d("Post execute: " , "NOOOT OKKKK"); 
       // Show the user a message that they did not enter the right login 

       Toast.makeText(getApplicationContext(), "Your email and password do not match out records. Please try again or create and account.", Toast.LENGTH_LONG).show(); 

       //final TextView login_error = (TextView) findViewById(R.id.login_error); 

       //textView.setText("My Text Hellosss - wrong login");    



      } 
      else 
      { 
       Log.d("Post execute: " , "OKKKK, result: " + result);  

       // Unwrap the stuff from the JSON string 

       String problem_title = null; 
       String problem_id = null; 

       try 
       { 
        JSONArray obj = new JSONArray(result); 
        JSONObject o = obj.getJSONObject(0);      

        Log.d("Title: " , "" + o.getString("problem_title"));  
        Log.d("id: " , "" + o.getString("problem_id"));  

        problem_title = o.getString("problem_title"); 
        problem_id = o.getString("problem_id"); 
       } 
       catch (Exception e) 
       { 
        Log.d("JSON ERRORZ: " , "some crap happened " + e.getMessage()); 
       } 

       // Now not sure what to do :) 

      } 
     }   
    } 
} 

我希望查詢遠程數據庫，獲得項目的列表並顯示出來。但是我不確定如何在從遠程服務器取回我的JSON後使用該信息更新屏幕。

而且，我的意見的XML文件是這樣的：

<?xml version="1.0" encoding="utf-8"?> 

<TextView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:padding="10dp" 
    android:textSize="16sp" > 
</TextView>  

但我也不太清楚它是如何需要爲顯示是動態地從數據庫中獲取的項目列表。

謝謝！

Answer 1

每次你想添加一些其他數據到你的列表視圖，使用適配器的add方法，然後調用適配器的notifyDataSetChanged()方法，以便更新UI中的更改。