AJAX实践之与服务器通信(1)(3)

xmlht.Open( " GET " ,server_XML_FileName, true );
xmlht.onreadystatechange = stateChange;
xmlht.Send( null );
function handleStateChange() {
　if (xmlHttp.readyState == 4 ) {
if (xmlHttp.status == 200 ) {
　xmlDoc.loadXML(xmlht.responseText);
} 
　} 
} 

import java.io. * ;
import javax.servlet. * ;
import javax.servlet.http. * ;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
public class PostingXMLExample extends HttpServlet {
protected void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
String xml = readXMLFromRequestBody(request);
Document xmlDoc = null ;
try {
xmlDoc = 
DocumentBuilderFactory.newInstance().newDocumentBuilder()
.parse( new ByteArrayInputStream(xml.getBytes()));
} 
catch (ParserConfigurationException e) {
System.out.println( " ParserConfigurationException: " + e);
} 
catch (SAXException e) {
System.out.println( " SAXException: " + e);
} 
/**/ /* Note how the Java implementation of 
the W3C DOM has the same methods
* as the JavaScript implementation, such as getElementsByTagName and 
* getNodeValue.
*/ 
NodeList selectedPetTypes = xmlDoc.getElementsByTagName( " type " );
String type = null ;
String responseText = " Selected Pets: " ;
for ( int i = 0 ; i < selectedPetTypes.getLength(); i ++ ) {
type = selectedPetTypes.item(i).getFirstChild().getNodeValue();
responseText = responseText + " " + type;
} 
response.setContentType( " text/xml " );
response.getWriter().print(responseText);
} 
private String readXMLFromRequestBody(HttpServletRequest request) {
StringBuffer xml = new StringBuffer();
String line = null ;
try {
BufferedReader reader = request.getReader();
while ((line = reader.readLine()) != null ) {
xml.append(line);
} 
} 
catch (Exception e) {
System.out.println( " Error reading XML: " + e.toString());
} 
return xml.toString();
} 
}