Android XML 阅读器出错

Question

我有一个可以正常工作的 XML 解析器，但是如果用户连接到未浏览应用程序的网络就会中断。放一个函数来检测用户是否连接，但是上面提到的问题，用户会连接但不能浏览。

我的代码如下：

public void chamaParser(){
    Boolean conected = Conectado(this);
    if(conected == true){
        new DoInBackground().execute();
    } else {
        mPullRefreshListViewRSS.onRefreshComplete();
        new AlertDialog.Builder(PullToRefreshListActivityRSS.this)
                .setTitle("Alerta!")
                .setMessage("Não foi possível estabelecer uma conexão com a Internet, verifique sua rede ou tente novamente mais tarde.")
                .setNeutralButton("OK", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {}
        }).show();
    }
}

public void do_update() {
    RssParser.parse();
}

public static boolean Conectado(Context context) {
    try {
        ConnectivityManager cm = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
        String LogSync = null;
        String LogToUserTitle = null;
        if (cm.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).isConnected()) {
            LogSync += "\nConectado a Internet 3G ";
            LogToUserTitle += "Conectado a Internet 3G ";
            return true;
        } else if(cm.getNetworkInfo(ConnectivityManager.TYPE_WIFI).isConnected()) {
            LogSync += "\nConectado a Internet WIFI ";
            LogToUserTitle += "Conectado a Internet WIFI ";
            return true;
        } else {
            LogSync += "\nNão possui conexão com a internet ";
            LogToUserTitle += "Não possui conexão com a internet ";
            return false;
        }
    } catch (Exception e) {
        return false;
    }
}

private class DoInBackground extends AsyncTask<Void, Void, Void> implements DialogInterface.OnCancelListener {
    private ProgressDialog dialog;

    protected void onPreExecute() {
        //dialog = ProgressDialog.show(PullToRefreshListActivityRSS.this, "", "Carregando...", true);
        dialog = ProgressDialog.show(PullToRefreshListActivityRSS.this, "", "Carregando...", true, true, new DialogInterface.OnCancelListener(){
                @Override
                public void onCancel(DialogInterface dialog) {
                    mPullRefreshListViewRSS.onRefreshComplete();
                    DoInBackground.this.cancel(true);
                    // finish();
                }
        });
    }

    protected Void doInBackground(Void... unused) { 
        PodcastAdapterRSS.topBarRSS=true;

        do_update(); 
        return null; 
    }

解析器 XML：

public class RssParser {

    public static void parse() {
        URL url;
        try {
            url = new URL("http://www.xxxx.com.br/feed/");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            if(conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
                DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
                DocumentBuilder db = dbf.newDocumentBuilder();
                Document doc;
                doc = db.parse(url.openStream());
                doc.getDocumentElement().normalize();
                NodeList itemLst = doc.getElementsByTagName("item");
                arrays.Title = new String[itemLst.getLength()];
                arrays.Link = new String[itemLst.getLength()];
                arrays.Description = new String[itemLst.getLength()];
                // arrays.PodcastMedia = new String[itemLst.getLength()];

                for(int i=0; i < itemLst.getLength(); i++){

                    Node item = itemLst.item(i);
                    if(item.getNodeType() == Node.ELEMENT_NODE){
                        Element ielem = (Element)item;
                        NodeList title = ielem.getElementsByTagName("title");
                        NodeList link = ielem.getElementsByTagName("link");
                        //NodeList description = ielem.getElementsByTagName("description"); 
                        NodeList content = ielem.getElementsByTagName("description");
                        //   NodeList media = ielem.getElementsByTagName("media:content");

                        //    String mediaurl = media.item(0).getAttributes().getNamedItem("url").getNodeValue();

                          arrays.Title[i] = title.item(0).getChildNodes().item(0).getNodeValue();
                          arrays.Link[i] = link.item(0).getChildNodes().item(0).getNodeValue();
                          arrays.Description[i] = content.item(0).getChildNodes().item(0).getNodeValue();

                    }
                }
            }

        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (DOMException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ParserConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

原木猫：

07-30 15:20:48.319: W/System.err(10997): java.net.UnknownHostException: www.xxxx.com.br 07-30 15：20：48.319：W/System.err（10997）：在 java.net.InetAddress.lookupHostByName(InetAddress.java:508) 07-30 15：20：48.319：W/System.err（10997）：在 java.net.InetAddress.getAllByNameImpl(InetAddress.java:296) 07-30 15：20：48.319：W/System.err（10997）：在 java.net.InetAddress.getAllByName(InetAddress.java:258) 07-30 15：20：48.319：W/System.err（10997）：在 org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection.(HttpConnection.java:69) 07-30 15:20:48.319: W/System.err(10997): 在 org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection.(HttpConnection.java:48) 07-30 15:20:48.319: W/System.err(10997): 在 org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection$Address.connect(HttpConnection.java:322) 07-30 15:20:48.319: W/System.err(10997): 在 org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnectionPool.get(HttpConnectionPool.java:89) 07-30 15:20:48.319: W/System.err(10997): 在 org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.getHttpConnection(HttpURLConnectionImpl.java:285) 07-30 15:20:48.319: W/System.err(10997): 在 org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.makeConnection(HttpURLConnectionImpl.java:267) 07-30 15:20:48.319: W/System.err(10997): 在 org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.retrieveResponse(HttpURLConnectionImpl.java:1018) 07-30 15:20:48.319: W/System.err(10997): 在 org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.getResponseCode(HttpURLConnectionImpl.java:726) 07-30 15:20:48.329: W/System.err(10997): 在 tabbar.rss.RssParser.parse(RssParser.java:30) 07-30 15:20:48.329: W / System.err（10997）：在 tabbar.rss.PullToRefreshListActivityRSS.do_update(PullToRefreshListActivityRSS.java:91) 07-30 15:20:48.329: W/System.err(10997): 在 tabbar.rss.PullToRefreshListActivityRSS$DoInBackground.doInBackground(PullToRefreshListActivityRSS.java:205) 07-30 15:20:48.329: W/System.err(10997): 在 tabbar.rss.PullToRefreshListActivityRSS$DoInBackground.doInBackground(PullToRefreshListActivityRSS.java:1) 07-30 15:20:48.329: W/System.err(10997): 在 android.os.AsyncTask$2.call(AsyncTask.java:185) 07-30 15:20:48.329: W / System.err（10997）：在 java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306) 07-30 15:20:48.329: W/System.err(10997): 在 java.util.concurrent.FutureTask.run(FutureTask.java:138) 07-30 15：20：48.329：W / System.err（10997）：在 java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 07-30 15:20:48.329: W/System.err(10997): 在 java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 07-30 15:20:48.329: W/System.err(10997): 在 java.lang.Thread.run(Thread.java:1019) 07-30 15:20:48.329: W/dalvikvm(10997): threadid=1: 线程以未捕获的异常退出 （组=0x401fc560）07-30 15:20:48.339：E/AndroidRuntime（10997）：致命 例外：主要 07-30 15:20:48.339：E/AndroidRuntime(10997)： java.lang.NullPointerException 07-30 15:20:48.339: E/AndroidRuntime(10997)：在 tabbar.rss.PullToRefreshListActivityRSS.populate_listview(PullToRefreshListActivityRSS.java:101) 07-30 15:20:48.339: E/AndroidRuntime(10997): 在 tabbar.rss.PullToRefreshListActivityRSS$DoInBackground.onPostExecute(PullToRefreshListActivityRSS.java:214) 07-30 15:20:48.339: E/AndroidRuntime(10997): 在 tabbar.rss.PullToRefreshListActivityRSS$DoInBackground.onPostExecute(PullToRefreshListActivityRSS.java:1) 07-30 15:20:48.339: E/AndroidRuntime(10997): 在 android.os.AsyncTask.finish(AsyncTask.java:417) 07-30 15:20:48.339: E/AndroidRuntime(10997)：在 android.os.AsyncTask.access$300(AsyncTask.java:127) 07-30 15：20：48.339：E/AndroidRuntime（10997）：在 android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429) 07-30 15:20:48.339: E/AndroidRuntime(10997): 在 android.os.Handler.dispatchMessage(Handler.java:99) 07-30 15：20：48.339：E/AndroidRuntime（10997）：在 android.os.Looper.loop(Looper.java:130) 07-30 15:20:48.339: E/AndroidRuntime(10997)：在 android.app.ActivityThread.main(ActivityThread.java:3689) 07-30 15：20：48.339：E/AndroidRuntime（10997）：在 java.lang.reflect.Method.invokeNative(Native Method) 07-30 15：20：48.339：E/AndroidRuntime（10997）：在 java.lang.reflect.Method.invoke(Method.java:507) 07-30 15:20:48.339: E/AndroidRuntime(10997)：在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:875) 07-30 15:20:48.339: E/AndroidRuntime(10997): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:633) 07-30 15：20：48.339：E/AndroidRuntime（10997）：在 dalvik.system.NativeStart.main(Native Method)

Answer 1

尝试将其添加到您的清单中：

<uses-permission android:name="android.permission.INTERNET" />

如果这不起作用，请查阅以下两个问题的答案：

Android java.net.UnknownHostException: Host is unresolved

Android java.net.UnknownHostException: Host is unresolved (strategy question)

Answer 2

您需要为您的 asynctask 提供一个超时处理程序，因为您已连接但未下载任何内容。设置大约 3000 - 5000 毫秒的超时时间

如何创建超时处理程序：

Android - Setting a Timeout for an AsyncTask?