Question

我试图在android中创建XML解析器，xml文件在我的localhost服务器上。我将URL设置为localhost-ed xml文件时出现NullPointerException错误，但是当我将xml文件上传到dropbox时，我的解析器正在工作。

错误消息：

...
Caused by: java.lang.NullPointerException
at java.io.StringReader.<init>(StringReader.java:47)
at com.learn.dhemas.franchise.XMLParser.getDomElement(XMLParser.java:74)
at com.learn.dhemas.franchise.fragmentLowongan$getDataOrder.doInBackground(fragmentLowongan.java:72)
...

XMLParser的，JAVA：

public class XMLParser {
    // constructor
    public XMLParser() {

    }

    /**
     * Getting XML from URL making HTTP request
     * @param url string
     * */
    public String getXmlFromUrl(String url) {
        String xml = null;

        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(url);

            HttpResponse httpResponse = httpClient.execute(httpGet);
            HttpEntity httpEntity = httpResponse.getEntity();
            xml = EntityUtils.toString(httpEntity);

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // return XML
        return xml;
    }

    /**
     * Getting XML DOM element
     * @param XML string
     * */
    public Document getDomElement(String xml){
        Document doc = null;
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        try {

            DocumentBuilder db = dbf.newDocumentBuilder();

            InputSource is = new InputSource();
            is.setCharacterStream(new StringReader(xml));
            doc = db.parse(is);

        } catch (ParserConfigurationException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        } catch (SAXException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        } catch (IOException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        }

        return doc;
    }

    /** Getting node value
     * @param elem element
     */
    public final String getElementValue( Node elem ) {
        Node child;
        if( elem != null){
            if (elem.hasChildNodes()){
                for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
                    if( child.getNodeType() == Node.TEXT_NODE  ){
                        return child.getNodeValue();
                    }
                }
            }
        }
        return "";
    }

    /**
     * Getting node value
     * @param Element node
     * @param key string
     * */
    public String getValue(Element item, String str) {
        NodeList n = item.getElementsByTagName(str);
        return this.getElementValue(n.item(0));
    }
}

和我的活动代码行（片段类）：

...
 @Override
    protected Void doInBackground(Void... params) {
        //Call parser
        XMLParser parser = new XMLParser();
        //String xml = parser.getXmlFromUrl("https://drive.google.com/uc?export=download&id=0B5bM7szIFKrpY2lPRHdCUUNscjA");
        String xml = parser.getXmlFromUrl("http://localhost/GetData.xml");
        Document doc = parser.getDomElement(xml);
...

任何帮助都将是apreciated

Answer 1

所以问题是，当我从应用程序指向localhost时，它将是模拟器上的localhost，而不是我的Web服务器中的localhost。要解决这个问题，我只需要创建一个虚拟本地网络，并为我的计算机提供一个IP地址，这样我就可以从模拟器访问IP。

Answer 2

您可以尝试在浏览器中打开网址：http://localhost/GetData.xml

无法解析localhost XML文件（NullPointerException）

2 个答案: