活動在android 2.x上運行良好，但在3.x及更高版本上崩潰

Question

我有一個其中包含xml Dom解析器的應用程序。 解析器活動由另一個片段中的按鈕激活。 當我運行該應用程序時，它可以在Gingerbread上正常運行，但是在Honeycomb和Jelly Bean上則每次都強制關閉。 這是班機信息和強制關閉時間的日志目錄文件。 如果有人對導致此問題的原因有任何想法，請告訴我。

我正在嘗試開設的課程

 public class CustomizedListView extends SherlockActivity {
// All static variables
static final String URL = "http://treymorgan.net/feed";
// XML node keys
static final String KEY_ID = "channel"; // parent node 
static final String KEY_ITEM = "item";
static final String KEY_TITLE = "title";
static final String KEY_PUB_DATE = "pubDate";
static final String KEY_LINK = "link";

ListView list;
LazyAdapter adapter;

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case android.R.id.home:
        // app icon in action bar clicked; go home
                    Intent intent = new Intent(this, MainActivity.class);
                    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(intent);
                    return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

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

    ActionBar bar = getSupportActionBar();
    bar.setDisplayHomeAsUpEnabled(true);



    final ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

    XMLParser parser = new XMLParser();
    String xml = parser.getXmlFromUrl(URL); // getting XML from URL
    Document doc = parser.getDomElement(xml); // getting DOM element

    NodeList nl = doc.getElementsByTagName(KEY_ITEM);
    // looping through all song nodes <song>
    for (int i = 0; i < nl.getLength(); i++) {
        // creating new HashMap
        HashMap<String, String> map = new HashMap<String, String>();
        Element e = (Element) nl.item(i);
        // adding each child node to HashMap key => value
        map.put(KEY_ITEM, parser.getValue(e, KEY_ITEM));
        map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
        map.put(KEY_PUB_DATE, parser.getValue(e, KEY_PUB_DATE));
        map.put(KEY_LINK, parser.getValue(e, KEY_LINK));

        // adding HashList to ArrayList
        songsList.add(map);
    }


    list=(ListView)findViewById(R.id.list);

    // Getting adapter by passing xml data ArrayList
    adapter=new LazyAdapter(this, songsList);        
    list.setAdapter(adapter);


    // Click event for single list row
    list.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {

            Uri uriUrl = Uri.parse(songsList.get(position).get(KEY_LINK));  
            Intent launchBrowser = new Intent(Intent.ACTION_VIEW, uriUrl);  
            startActivity(launchBrowser);  



             }

    });
}   
}

原木貓

08-29 03:28:48.603: E/AndroidRuntime(658): FATAL EXCEPTION: main
08-29 03:28:48.603: E/AndroidRuntime(658): java.lang.RuntimeException: Unable to start        activity ComponentInfo{com.threesixteenapps.treymorgan/com.threesixteenapps.treymorgan.CustomizedListView}: android.os.NetworkOnMainThreadException
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.os.Handler.dispatchMessage(Handler.java:99)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.os.Looper.loop(Looper.java:137)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.app.ActivityThread.main(ActivityThread.java:4424)
08-29 03:28:48.603: E/AndroidRuntime(658):  at java.lang.reflect.Method.invokeNative(Native Method)
08-29 03:28:48.603: E/AndroidRuntime(658):  at java.lang.reflect.Method.invoke(Method.java:511)
08-29 03:28:48.603: E/AndroidRuntime(658):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
08-29 03:28:48.603: E/AndroidRuntime(658):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
08-29 03:28:48.603: E/AndroidRuntime(658):  at dalvik.system.NativeStart.main(Native Method)
08-29 03:28:48.603: E/AndroidRuntime(658): Caused by: android.os.NetworkOnMainThreadException
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
08-29 03:28:48.603: E/AndroidRuntime(658):  at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
08-29 03:28:48.603: E/AndroidRuntime(658):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
08-29 03:28:48.603: E/AndroidRuntime(658):  at java.net.InetAddress.getAllByName(InetAddress.java:220)
08-29 03:28:48.603: E/AndroidRuntime(658):  at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
08-29 03:28:48.603: E/AndroidRuntime(658):  at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
08-29 03:28:48.603: E/AndroidRuntime(658):  at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
08-29 03:28:48.603: E/AndroidRuntime(658):  at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
08-29 03:28:48.603: E/AndroidRuntime(658):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
08-29 03:28:48.603: E/AndroidRuntime(658):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
08-29 03:28:48.603: E/AndroidRuntime(658):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
08-29 03:28:48.603: E/AndroidRuntime(658):  at com.threesixteenapps.treymorgan.XMLParser.getXmlFromUrl(XMLParser.java:45)
08-29 03:28:48.603: E/AndroidRuntime(658):  at com.threesixteenapps.treymorgan.CustomizedListView.onCreate(CustomizedListView.java:64)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.app.Activity.performCreate(Activity.java:4465)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
08-29 03:28:48.603: E/AndroidRuntime(658):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
08-29 03:28:48.603: E/AndroidRuntime(658):  ... 11 more

如果需要更多信息，我將很樂意為您提供。 謝謝您的幫助

Answer 1

Android 3.0及更高版本不允許您在ui線程中執行任何聯網任務（ 請參閱此文章 ）。
解決方案是實現AsyncTask或可能的Loader 。

編輯：我做了一個簡單的示例，說明如何在Activity中實現AsyncTask。 我刪除了一些部分或將其替換為注釋，以使其簡短。 只需將其與您的代碼合並，它就可以正常工作（將MyActivity替換為您自己的代碼等）。

public class MyActivity extends Activity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        //super onCreate, setup your content, actionbar etc.

        AsyncTask getxml = new MyAsyncTask();
        getxml.execute(URL);
    }

    private class MyAsyncTask extends AsyncTask<String, Integer, Void>{
        private static final int RESULT_GOT_XML = 1;
        private static final int RESULT_FAILED = 0;
        private ArrayList<HashMap<String, String>> asyncList;
        public MyAsyncTask(){
            asyncList = new ArrayList<HashMap<String, String>>();
        }

        @Override
        protected Integer doInBackground(String... url) {

            try{
                XMLParser parser = new XMLParser();
                String xml = parser.getXmlFromUrl(url[0]);
                Document doc = parser.getDomElement(xml);

                NodeList nl = doc.getElementsByTagName(KEY_ITEM);
                for (int i = 0; i < nl.getLength(); i++) {
                    //...perform the parsing and add to list:
                    asyncList.add(map);
                }
            }catch(IOException e){
                Log.e("MyAsync", "could not complete xml retrieval/parsing", e);
                return RESULT_FAILED;
            }
            return RESULT_GOT_XML;
        }

        @Override
        protected void onPostExecute(Integer result) {
            switch (result) {
            case RESULT_FAILED:
                Toast.makeText(MyActivity.this, "Could not get data", Toast.LENGTH_SHORT).show();
                break;
            case RESULT_GOT_XML:
                songsList.addAll(asyncList);
                list=(ListView)findViewById(R.id.list);
                adapter=new LazyAdapter(this, songsList);        
                list.setAdapter(adapter);

                list.setOnItemClickListener(yourclicklistener);
            default:
                Log.wtf("MyAsync","got unexpected result: "+result);
                break;
            }
        }
    }
}

Answer 2

Caused by: android.os.NetworkOnMainThreadException

您正在主線程上執行網絡操作 ，這在較新的API中是不允許的。 使用DownloadManager或將XMLParser移到新線程，也許是AsyncTask。