获取和解析XML时出错

Question

public String getMetaData() {
    String errors = "";
    try {
        URL url = new URL("http://in2streaming.com:9999/stats?sid=1.xml");
        URLConnection conn = url.openConnection();

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        // Error Here:
        Document doc = db.parse(conn.getInputStream().toString());

        // get the root node
        NodeList nodeList = doc.getElementsByTagName("SHOUTCASTSERVER");
        Node node=nodeList.item(0);
        // the  node has three child nodes
        for (int i = 0; i < node.getChildNodes().getLength(); i++) {
            Node temp=node.getChildNodes().item(i);
            if(temp.getNodeName().equalsIgnoreCase("SONGTITLE")){
                return temp.getTextContent();
            }
        }
        return "Couldn't reach XML";
    }
    catch (Exception e) {
        return "Exception ";
    }
}

Calling this function via Runnable, Got Exception android.os.NetworkOnMainThreadException I might change the link to http://in2streaming.com:9999/7.html and use HTMl parser instead

// Refresh meta data
private final Runnable refresh_meta = new Runnable() {
    @Override
    public void run() {
        Toast.makeText(m_context, getMetaData(), Toast.LENGTH_SHORT).show();
        m_handler.postDelayed(this, 5000);
    }
};

Answer 1

For NetworkOnMainThreadException(You can also use AsyncTask):

Executors.newSingleThreadExecutor().submit(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(MainActivity.this, getMetaData(), Toast.LENGTH_SHORT).show();
            }
        });

If you want to Schedule every 5 sec.

You can use ScheduledExecutorService

ScheduledExecutorService worker = Executors.newSingleThreadScheduledExecutor();

        worker.scheduleAtFixedRate(refresh_meta,
                1,  //initial delay
                5, //run every 5 seconds
                TimeUnit.SECONDS);

And Update your Runnable as

private Runnable refresh_meta = new Runnable() {
        @Override
        public void run() {
            final String text = getMetaData();

            runOnUiThread(new Runnable() {
                              @Override
                              public void run() {
                                  Toast.makeText(m_context, text, Toast.LENGTH_SHORT).show();
                              }
                          }
            );


        }
    };

Also,

Change Document doc = db.parse(conn.getInputStream().toString()); to

Document doc = db.parse(conn.getInputStream());

Answer 2

First some remarks:

a) Do not muffle the exceptions like you do here :

catch (Exception e) {
    return "Exception ";
}

This way you will never know what was the exception that was thrown. It is better to log/print the exception's stack trace, for example:

catch (Exception e) {
    Log.e("TAG", "Error", e);
    return "Exception";
}

b) conn.getInputStream().toString() doesn't do what you suppose it does (convert the InputStream to String ). DocumentBuilder 's parse method takes an InputStream as parameter no need to convert it to String .

Having the above in mind here is your method:

public String getMetaData() {
    String errors = "";
    try {
        URL url = new URL("http://in2streaming.com:9999/stats?sid=1.xml");
        URLConnection conn = url.openConnection();

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        // Error Here:
        Document doc = db.parse(conn.getInputStream());

        // get the root node
        NodeList nodeList = doc.getElementsByTagName("SHOUTCASTSERVER");
        Node node=nodeList.item(0);
        // the  node has three child nodes
        for (int i = 0; i < node.getChildNodes().getLength(); i++) {
            Node temp=node.getChildNodes().item(i);
            if(temp.getNodeName().equalsIgnoreCase("SONGTITLE")){
                return temp.getTextContent();
            }
        }
        return "Couldn't reach XML";
    }
    catch (Exception e) {
        Log.e("TAG", "Error in getMetaData()", e);
        return "Exception ";
    }
}

Try running your app again and if an error arises from this method it will be printed in your logcat with the message "Error in getMetaData()". Update your question accordingly with the error to let other members help you.