Question

我在使用以下代码从url检索xml时遇到一些问题：

    private static String getAlbumArt(String artistName, String albumName){
        try{
        XMLParser xml_parser = new XMLParser();
        String xml = xml_parser.getXmlFromUrl(getAlbumURL(artistName, albumName));
        Document doc = xml_parser.getDomElement(xml);
        NodeList N = doc.getElementsByTagName("album");
        Node node = N.item(0);
        NodeList N2 = node.getChildNodes();
        System.out.println("1------");
            for (int i = 0; i < N2.getLength(); i++) {
                Node detailNode = N2.item(i);
                if (detailNode.getNodeType() == Node.ELEMENT_NODE)
                    {
                    System.out.println("2------");
                    if (detailNode.getNodeName().equalsIgnoreCase("image")) 
                    {
                        String sizeVal = ((Element) detailNode).getAttribute("size");
                        String url = detailNode.getTextContent();
                        if (sizeVal.equalsIgnoreCase("large")) {
                            return url;
                        }
                    }
                    }
        }
        }
        catch (Exception e){
        }
        return null;
    }

我在上面的代码中调用的xml函数：

public String getXmlFromUrl(String url) {
    String xml = null;
    try {
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);
        HttpResponse httpResponse = httpClient.execute(httpPost);
        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;
}

getAlbumURL：

    public static String getAlbumURL(String artist, String album){
        return URL_METHOD + METHOD_GETALBUM + AMPERSAND
                + API_KEY + AMPERSAND
                + PARAM_ARTIST + artist + AMPERSAND
                + PARAM_ALBUM + album;
    }

XMLPARSER：

public class XMLParser {

// constructor
public XMLParser() {
}

//Get XML from URL
public String getXmlFromUrl(String url) {
    String xml = null;
    try {
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);
        HttpResponse httpResponse = httpClient.execute(httpPost);
        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;
}

//Get dom element
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;
}

//Get nod 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 "";
 }

//Get element value
 public String getValue(Element item, String str) {     
     NodeList nlList = item.getElementsByTagName(str).item(0).getChildNodes();
     Node nValue = (Node) nlList.item(0);
     return nValue.getNodeValue();
    }

}

有什么想法吗？我真的不知道出了什么问题。我之前使用过它并且有效。

Answer 1

我拉了你的代码并试了一下。我重新编写了“getAlbumURL”来返回一个硬编码的字符串。我使用了您在评论中提供的地址，但失败了。但是，该xml不会链接到任何专辑封面。所以我尝试了正确的专辑名称“In％20ra * i * nbows”。像梦一样工作。

首先，验证您的常量是否为您提供了您认为应该使用的内容（您已经做过），然后验证您的测试数据。你的代码看起来很好。

Answer 2

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();在try{}块之后添加这些行：

dbf.setIgnoringComments(true);
dbf.setCoalescing(true);

从URL检索XML

2 个答案: