Android 3.0 Honeycomb 解析 RSS 提要的问题

Question

我正在尝试在蜂窝 3.0 中解析 rss 提要，但它给出的错误如下。

错误/AndroidNews::PullFeedParser(444): android.os.NetworkOnMainThreadException

我在 android 较低版本中尝试了相同的代码，但它在 Honeycomb 中不起作用。 请提出一些帮助

这是主要活动

try{
    FeedParser parser = new XmlPullFeedParser(feedUrl);
    messages = parser.parse();
    titles = new ArrayList<String>(messages.size());
    String description ="";//= new ArrayList<String>(messages.size());
    for (Message msg : messages){
        description = msg.getDescription().toString();
        Log.v("Desc", description);
            titles.add(description);
        }
    } catch (Throwable t){
    Log.e("AndroidNews",t.getMessage(),t);
}

我正在使用扩展 BaseFeedParser 的 XmlPullFeedParser

public class XmlPullFeedParser extends BaseFeedParser {

    public XmlPullFeedParser(String feedUrl) {
        super(feedUrl);
    }

    public List<Message> parse() {
        List<Message> messages = null;
        XmlPullParser parser = Xml.newPullParser();
        try {
            // auto-detect the encoding from the stream
            parser.setInput(this.getInputStream(), null);
            int eventType = parser.getEventType();
            Message currentMessage = null;
            boolean done = false;
            while (eventType != XmlPullParser.END_DOCUMENT && !done){
                String name = null;
                switch (eventType){
                    case XmlPullParser.START_DOCUMENT:
                        messages = new ArrayList<Message>();
                        break;
                    case XmlPullParser.START_TAG:
                        name = parser.getName();
                        if (name.equalsIgnoreCase(ITEM)){
                            currentMessage = new Message();
                        } else if (currentMessage != null){
                            if (name.equalsIgnoreCase(LINK)){
                                currentMessage.setLink(parser.nextText());
                            } else if (name.equalsIgnoreCase(DESCRIPTION)){
                                currentMessage.setDescription(parser.nextText());
                            } else if (name.equalsIgnoreCase(PUB_DATE)){
                                currentMessage.setDate(parser.nextText());
                            } else if (name.equalsIgnoreCase(TITLE)){
                                currentMessage.setTitle(parser.nextText());
                            }   
                        }
                        break;
                    case XmlPullParser.END_TAG:
                        name = parser.getName();
                        if (name.equalsIgnoreCase(ITEM) && currentMessage != null){
                            messages.add(currentMessage);
                        } else if (name.equalsIgnoreCase(CHANNEL)){
                            done = true;
                        }
                        break;
                }
                eventType = parser.next();
            }
        } catch (Exception e) {
            Log.e("AndroidNews::PullFeedParser", e.getMessage(), e);
            throw new RuntimeException(e);
        }
        return messages;
    }
}

这是 BaseFeedParser：

public class BaseFeedParser implements FeedParser {

    // names of the XML tags
    static final String CHANNEL = "channel";
    static final String PUB_DATE = "pubDate";
    static final  String DESCRIPTION = "description";
    static final  String LINK = "link";
    static final  String TITLE = "title";
    static final  String ITEM = "item";
    static final  String BODY = "body";

    private final URL feedUrl;

    protected BaseFeedParser(String feedUrl){
        try {
            this.feedUrl = new URL(feedUrl);
        } catch (MalformedURLException e) {
            throw new RuntimeException(e);
        }
    }

    protected InputStream getInputStream() {
        try {
            return feedUrl.openConnection().getInputStream();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public List<Message> parse() {
        // TODO Auto-generated method stub
        return null;
    }
}

这是 FeedParser：

public interface FeedParser {
    List<Message> parse();
}

这是消息类：

public class Message implements Comparable<Message>{
    static SimpleDateFormat FORMATTER = 
        new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss Z");
    private String title;
    private URL link;
    private String description;
    private Date date;
    private String body;

    public String getTitle() {
        return title;
    }

    public String getBody() {
        return body;
    }

    public void setTitle(String title) {
        this.title = title.trim();
    }
    // getters and setters omitted for brevity 
    public URL getLink() {
        return link;
    }

    public void setLink(String link) {
        try {
            this.link = new URL(link);
        } catch (MalformedURLException e) {
            throw new RuntimeException(e);
        }
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description.trim();
    }

    public String getDate() {
        return FORMATTER.format(this.date);
    }

    public void setDate(String date) {
        // pad the date if necessary
        while (!date.endsWith("00")){
            date += "0";
        }
        try {
            this.date = FORMATTER.parse(date.trim());
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
    }

    public Message copy(){
        Message copy = new Message();
        copy.title = title;
        copy.link = link;
        copy.description = description;
        copy.date = date;
        copy.body = body;
        return copy;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("Title: ");
        sb.append(title);
        sb.append("Body: ");
        sb.append(body);
        sb.append('\n');
        sb.append("Date: ");
        sb.append(this.getDate());
        sb.append('\n');
        sb.append("Link: ");
        sb.append(link);
        sb.append('\n');
        sb.append("Description: ");
        sb.append(description);
        return sb.toString();
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((date == null) ? 0 : date.hashCode());
        result = prime * result
                + ((description == null) ? 0 : description.hashCode());
        result = prime * result + ((link == null) ? 0 : link.hashCode());
        result = prime * result + ((title == null) ? 0 : title.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Message other = (Message) obj;
        if (date == null) {
            if (other.date != null)
                return false;
        } else if (!date.equals(other.date))
            return false;
        if (description == null) {
            if (other.description != null)
                return false;
        } else if (!description.equals(other.description))
            return false;
        if (link == null) {
            if (other.link != null)
                return false;
        } else if (!link.equals(other.link))
            return false;
        if (title == null) {
            if (other.title != null)
                return false;
        } else if (!title.equals(other.title)){
            return false;
        } else if (!body.equals(other.body))    
            return false;
        return true;
    }

    public int compareTo(Message another) {
        if (another == null) return 1;
        // sort descending, most recent first
        return another.date.compareTo(date);
    }
}

Answer 1

这里的错误消息几乎可以告诉您发生了什么——您正试图访问主线程上的网络。你真的不应该在任何版本的 android 上这样做，因为它可以（阅读：将）导致你的 UI 在连接处理时挂起。

有一些方法可以关闭错误，但我不会进入它们：你不应该这样做。

相反，您希望在后台线程中完成这项工作，并将最小的处理程序发布回 UI 线程。我没有方便的示例（现在在我的平板电脑上），但如果找不到，请告诉我。

..编辑.. 好的，这是一个简单的例子。这需要一个带有文本视图（id “text”）的活动，当然还有 INTERNET 权限。如果您有任何问题，请告诉我！

public class MainActivity extends Activity {
private TextView mTextView;

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

    mTextView = (TextView) findViewById(R.id.text);

    // start our call in a new thread
    (new Thread(new Runnable() {
        @Override
        public void run() {
            fetchPage();
        }
    })).start();
}

private void fetchPage() {
    try {
        URL url = new URL("http://stackoverflow.com/feeds");
        HttpURLConnection c = (HttpURLConnection) url.openConnection();
        c.setRequestMethod("GET");
        c.setDoOutput(true);
        c.connect();

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        InputStream is = c.getInputStream();

        byte[] buffer = new byte[1024];
        int len1 = 0;
        while ((len1 = is.read(buffer)) != -1) {
            bos.write(buffer, 0, len1);
        }
        bos.close();
        is.close();

        // Remember, all UI things must occur back on the UI thread!
        final String text = bos.toString();
        this.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mTextView.setText(text);
            }
        });
    } catch (final IOException ioe) {
        this.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(MainActivity.this, ioe.getMessage(), Toast.LENGTH_LONG).show();
            }
        });
    }
}

谢谢， --兰迪