我从服务器检索XML，将其保存到SD卡中，然后解析该XML。我得到了这个例外：
03-19 13:53:26.943: E/AndroidRuntime(12512): FATAL EXCEPTION: main
03-19 13:53:26.943: E/AndroidRuntime(12512): java.lang.NullPointerException.
我正在使用此代码：
/** Create Object For SiteList Class */
SitesList sitesList = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
DownloadFromUrl("http://www.androidpeople.com/wp- content/uploads/2010/06/example.xml","example.xml");
/** Create a new layout to display the view */
LinearLayout layout = new LinearLayout(this);
layout.setOrientation(1);
/** Create a new textview array to display the results */
TextView name[];
TextView website[];
TextView category[];
try {
/** Handling XML */
String path = Environment.getExternalStorageDirectory() +"../xmls"+"/example.xml";
File file = new File(path);
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xr = sp.getXMLReader();
/** Create handler to handle XML Tags ( extends DefaultHandler ) */
DataHandler myXMLHandler = new DataHandler();
xr.setContentHandler(myXMLHandler);
xr.parse(new InputSource(new InputStreamReader(new FileInputStream(file))));//parse(new InputSource(sourceUrl.openStream()));
} catch (Exception e) {
System.out.println("XML Pasing Excpetion = " + e);
}
/** Get result from DataHandler SitlesList Object */
sitesList = DataHandler.sitesList;
/** Assign textview array lenght by arraylist size */
name = new TextView[sitesList.getName().size()];
website = new TextView[sitesList.getWebsite().size()];
category = new TextView[sitesList.getCategory().size()];
/** Set the result text in textview and add it to layout */
for (int i = 0; i < sitesList.getName().size(); i++) {
name[i] = new TextView(this);
name[i].setText("Name = "+sitesList.getName().get(i));
website[i] = new TextView(this);
website[i].setText("Website = "+sitesList.getWebsite().get(i));
category[i] = new TextView(this);
category[i].setText("Website Category = "+sitesList.getCategory().get(i));
layout.addView(name[i]);
layout.addView(website[i]);
layout.addView(category[i]);
}
/** Set the layout view to display */
setContentView(layout);
}
private void DownloadFromUrl(String DownloadUrl, String fileName)
{
URL url;
File root = android.os.Environment.getExternalStorageDirectory();
File dir = new File (root.getAbsolutePath() + "/xmls");
if(dir.exists()==false) {
dir.mkdirs();
}
try {
url = new URL(DownloadUrl);
File file = new File(dir, fileName);
Log.d("DownloadManager", "download begining");
Log.d("DownloadManager", "download url:" + url);
Log.d("DownloadManager", "downloaded file name:" + fileName);
/* Open a connection to that URL. */
URLConnection ucon = url.openConnection();
/*
* Define InputStreams to read from the URLConnection.
*/
InputStream is = ucon.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
/*
* Read bytes to the Buffer until there is nothing more to read(-1).
*/
ByteArrayBuffer baf = new ByteArrayBuffer(5000);
int current = 0;
while ((current = bis.read()) != -1) {
baf.append((byte) current);
}
/* Convert the Bytes read to a String. */
FileOutputStream fos = new FileOutputStream(file);
fos.write(baf.toByteArray());
fos.flush();
fos.close();
//Log.d("DownloadManager", "download ready in" + ((System.currentTimeMillis() - startTime) / 1000) + " sec");
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} //you can write here any link
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
我的处理程序类是：
Boolean currentElement = false;
Context theContext;
String currentValue = null;
public static SitesList sitesList = null;
public static SitesList getSitesList()
{
return sitesList;
}
public static void setSitesList(SitesList sitesList)
{
DataHandler.sitesList = sitesList;
}
@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException
{
super.startElement(uri, localName, qName, attributes);
currentElement = true;
if (localName.equals("maintag"))
{
/** Start */
sitesList = new SitesList();
}
else if (localName.equals("website"))
{
/** Get attribute value */
String attr = attributes.getValue("category");
sitesList.setCategory(attr);
}
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
super.endElement(uri, localName, qName);
currentElement = false;
/** set value */
if (localName.equalsIgnoreCase("name"))
sitesList.setName(currentValue);
else if (localName.equalsIgnoreCase("website"))
sitesList.setWebsite(currentValue);
}
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
// TODO Auto-generated method stub
super.characters(ch, start, length);
if (currentElement)
{
currentValue = new String(ch, start, length);
currentElement = false;
}
}
我的列表类是：
/** Variables */
private ArrayList name = new ArrayList();
private ArrayList website = new ArrayList();
private ArrayList category = new ArrayList();
/** In Setter method default it will return arraylist
* change that to add */
public ArrayList getName() {
return name;
}
public void setName(String name) {
this.name.add(name);
}
public ArrayList getWebsite() {
return website;
}
public void setWebsite(String website) {
this.website.add(website);
}
public ArrayList getCategory() {
return category;
}
public void setCategory(String category) {
this.category.add(category);
}
XML文件已下载并正确保存到SD卡中但未解析。
答案 0 :(得分：0)
SAX（Simple API for XML）是一种基于事件的顺序访问解析器API，由XML文档的XML-DEV邮件列表开发。 SAX提供了一种从XML文档读取数据的机制，该机制可替代文档对象模型（DOM）提供的数据。在DOM作为整体对文档进行操作的地方，SAX解析器按顺序对每个XML文档进行操作
请参阅此link了解您的解决方案。
它会帮助你。