android - Android RSS 阅读器在启动时崩溃

Question

我正在为 Android 开发一个简单的 RSS 阅读器。这是我的代码：

package com.example.rssreader;

public class MainActivity extends ListActivity {

List headlines;
List links;
static final int DIALOG_ERROR_CONNECTION = 1;

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

    if (!isOnline(this)) {
        showDialog(DIALOG_ERROR_CONNECTION);
    } else {

    // initializing instance variables
    headlines = new ArrayList();
    links = new ArrayList();

    try {
        URL url = new URL("http://feeds.pcworld.com/pcworld/latestnews");

        XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
        factory.setNamespaceAware(false);
        XmlPullParser xpp = factory.newPullParser();

        // We will get the XML from an input stream
        xpp.setInput(getInputStream(url), "UTF_8");

        /* We will parse the XML content looking for the <title> tag which appears inside the <item> tag.
         * However, we should take in consideration that the rss feed name also is enclosed in a <title> tag.
         * As we know, every feed begins with these lines: <channel><title>Feed_Name</title>...
         * so we should skip the <title> tag which is a child of <channel> tag,
         * and take in consideration only <title> tag which is a child of <item>
         * 
         * In order to achieve this, we will make use of a boolean variable.
         */

        boolean insideItem = false;

        // Returns the type of current event: START_TAG, END_TAG, etc..
        int eventType = xpp.getEventType();
        while (eventType != XmlPullParser.END_DOCUMENT) {
            if (eventType == XmlPullParser.START_TAG) {

                if (xpp.getName().equalsIgnoreCase("item")) {
                    insideItem = true;
                } else if (xpp.getName().equalsIgnoreCase("title")) {
                    if (insideItem)
                        headlines.add(xpp.nextText()); // extract the headline
                } else if (xpp.getName().equalsIgnoreCase("link")) {
                    if (insideItem)
                        links.add(xpp.nextText()); // extract the link of article
                }
            } else if (eventType == XmlPullParser.END_TAG && xpp.getName().equalsIgnoreCase("item")) {
                insideItem = false;
            }

            eventType = xpp.next(); // move to next element
        }
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (XmlPullParserException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    // Binding data
    ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, headlines);

    setListAdapter(adapter);

    }
}

public InputStream getInputStream(URL url) {
    try {
        return url.openConnection().getInputStream();
    } catch (IOException e) {
        return null;
    }
}

public boolean isOnline(Context c) {
    ConnectivityManager cm = (ConnectivityManager) c.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo ni = cm.getActiveNetworkInfo();

    if(ni!=null && ni.isConnected())
        return true;
    else
        return false;
}

@Override
protected Dialog onCreateDialog(int id) {
    Dialog dialog = null;
    switch(id) {
    case DIALOG_ERROR_CONNECTION:
        AlertDialog.Builder errorDialog = new AlertDialog.Builder(this);
        errorDialog.setTitle("Error");
        errorDialog.setMessage("No internet connection.");
        errorDialog.setNeutralButton("OK", new DialogInterface.OnClickListener() {

            public void onClick(DialogInterface dialog, int id) {
                dialog.dismiss();
            }
        });

        AlertDialog errorAlert = errorDialog.create();
        return errorAlert;

        default:
            break;
    }
    return dialog;
}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    Uri uri = Uri.parse((String) links.get(position));
    Intent intent = new Intent(Intent.ACTION_VIEW, uri);
    startActivity(intent);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}
}

我在代码中没有任何错误，但是当我尝试启动它时，它崩溃了。我不知道为什么。这是我的日志：

09-19 09:49:18.207: E/AndroidRuntime(3360): FATAL EXCEPTION: main
09-19 09:49:18.207: E/AndroidRuntime(3360): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.rssreader/com.example.rssreader.MainActivity}: android.os.NetworkOnMainThreadException
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.app.ActivityThread.access$600(ActivityThread.java:127)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.os.Looper.loop(Looper.java:137)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.app.ActivityThread.main(ActivityThread.java:4441)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at java.lang.reflect.Method.invokeNative(Native Method)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at java.lang.reflect.Method.invoke(Method.java:511)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at dalvik.system.NativeStart.main(Native Method)
09-19 09:49:18.207: E/AndroidRuntime(3360): Caused by: android.os.NetworkOnMainThreadException
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1108)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.io.IoBridge.connectErrno(IoBridge.java:133)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.io.IoBridge.connect(IoBridge.java:118)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at java.net.Socket.connect(Socket.java:849)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:77)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:117)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:303)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at com.example.rssreader.MainActivity.getInputStream(MainActivity.java:108)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at com.example.rssreader.MainActivity.onCreate(MainActivity.java:57)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.app.Activity.performCreate(Activity.java:4465)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
09-19 09:49:18.207: E/AndroidRuntime(3360):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
09-19 09:49:18.207: E/AndroidRuntime(3360):     ... 11 more

我希望你们中的一些人可以帮助我！

score 3 · Accepted Answer

这个问题有两个解决方案。

1）不要在主 UI 线程中编写网络调用，为此使用异步任务。

2) 在 setContentView(R.layout.activity_main); 之后将以下代码写入 MainActivity 文件；

if (android.os.Build.VERSION.SDK_INT > 9) {
    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy);
}

score 0 · Accepted Answer

Caused by: java.lang.SecurityException: ConnectivityService: Neither user 10111 nor current process has android.permission.ACCESS_NETWORK_STATE.

添加权限：

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

android - Android RSS 阅读器在启动时崩溃

2 回答 2

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