从android中获取XML url

我是android的新手。我想从网址获取XML。我的应用程序非常简单。 MainActivity有一个导航到下一个屏幕并显示XML数据的按钮从android中获取XML url

以下是我从在线源获得的示例代码，但它对我无效。它什么都不显示。从logcat的

private class LongOperation extends AsyncTask<String, Void, LinearLayout> { 

    @Override 
    protected LinearLayout doInBackground(String... string) { 
     LinearLayout layout = new LinearLayout(DevicesActivity.this); 
     layout.setOrientation(1); 
     /** Create a new textview array to display the results */ 
     TextView name[]; 
     TextView website[]; 
     TextView category[]; 
     try { 
      URL url = new URL(
        "http://www.androidpeople.com/wp-content/uploads/2010/06/example.xml"); 
      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 
      DocumentBuilder db = dbf.newDocumentBuilder(); 
      Document doc = db.parse(new InputSource(url.openStream())); 
      doc.getDocumentElement().normalize(); 
      NodeList nodeList = doc.getElementsByTagName("item"); 
      /** Assign textview array lenght by arraylist size */ 
      name = new TextView[nodeList.getLength()]; 
      website = new TextView[nodeList.getLength()]; 
      category = new TextView[nodeList.getLength()]; 
      for (int i = 0; i < nodeList.getLength(); i++) { 
       Node node = nodeList.item(i); 
       name[i] = new TextView(DevicesActivity.this); 
       website[i] = new TextView(DevicesActivity.this); 
       category[i] = new TextView(DevicesActivity.this); 
       Element fstElmnt = (Element) node; 
       NodeList nameList = fstElmnt.getElementsByTagName("name"); 
       Element nameElement = (Element) nameList.item(0); 
       nameList = nameElement.getChildNodes(); 
       name[i].setText("Name = " 
         + ((Node) nameList.item(0)).getNodeValue()); 
       NodeList websiteList = fstElmnt.getElementsByTagName("website"); 
       Element websiteElement = (Element) websiteList.item(0); 
       websiteList = websiteElement.getChildNodes(); 
       website[i].setText("Website = " 
         + ((Node) websiteList.item(0)).getNodeValue()); 
       category[i].setText("Website Category = " 
         + websiteElement.getAttribute("category")); 
       layout.addView(name[i]); 
       layout.addView(website[i]); 
       layout.addView(category[i]); 
      } 
     } catch (Exception e) { 
      System.out.println("XML Pasing Excpetion = " + e); 
     } 
     /** Set the layout view to display */ 
     return layout; 
    }  

    protected void onPostExecute(LinearLayout result) { 
     setContentView(result); 
     // here you will get the result 
    } 
} 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    /** Create a new layout to display the view */ 
    //setContentView(R.layout.activity_devices); 
    new LongOperation().execute(""); 

}

日志

05-29 16:00:50.972: I/Choreographer(6780): Skipped 33 frames! The application may be doing too much work on its main thread. 
05-29 16:00:51.122: D/gralloc_goldfish(6780): Emulator without GPU emulation detected. 
05-29 16:00:54.252: I/System.out(6780): XML Pasing Excpetion = android.os.NetworkOnMainThreadException 
05-29 16:00:55.663: I/Choreographer(6780): Skipped 71 frames! The application may be doing too much work on its main thread.

更新

05-29 19:55:38.952: E/Trace(7739): error opening trace file: No such file or directory (2) 
05-29 19:55:41.022: D/gralloc_goldfish(7739): Emulator without GPU emulation detected. 
05-29 19:55:48.472: I/Choreographer(7739): Skipped 31 frames! The application may be doing too much work on its main thread. 
05-29 19:55:49.182: I/Choreographer(7739): Skipped 68 frames! The application may be doing too much work on its main thread. 
05-29 19:55:50.662: I/System.out(7739): XML Pasing Excpetion = java.lang.SecurityException: Permission denied (missing INTERNET permission?)

来源

2013-05-29 Michael

你不能做一个HTTP调用在你的主线程，使用的AsyncTask代替。

创建延伸的的AsyncTask一个内部类，做doInBackground方法中你的工作

private class LongOperation extends AsyncTask<String, Void, String> { 

    @Override 
    protected String doInBackground(String... params) { 
     // do your call here 
    }  

    @Override 
    protected void onPostExecute(String result) {    
     // here you will get the result 
    } 
}

你可以把它在你的onCreate这样的：

new LongOperation().execute("myParams");

来源

2013-05-29 16:22:00 Enrichman

谢谢，我更新了我的代码，但仍然没有显示任何内容。我不知道应该在哪里插入这行setContentView（result）; – Michael

如果您尝试返回文档并尝试在onPostExecute中更新您的视图，会发生什么情况？ – Enrichman

什么都没有发生，我更新了日志。 – Michael

机器人返回此异常时，一些网络操作正在主线程中运行。你应该尝试asynctask类。其余的代码似乎没问题。阅读关于asynctask的文档。希望这可以帮助！

来源

2013-05-29 16:30:05 ERed

谢谢，我更新了我的代码，但仍然没有显示任何内容。 – Michael

你应该把你的androidmanifest.xml文件中的internet权限 – ERed

从android中获取XML url

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