首先看下看下相对简单些的--向服务器发送一个包含有名/值对的简单查询串，在这种情况下XHP即可以用GET也可以用POST。

GET function doRequestUsingGET() { 　createXMLHttpRequest(); 　var queryString = " GetAndPostExample? " ; 　queryString = queryString + createQueryString()+ " &timeStamp= " + new Date().getTime(); 　xmlHttp.onreadystatechange = handleStateChange; 　xmlHttp.open( " GET " , queryString, true ); 　xmlHttp.send( null ); } POST function doRequestUsingPOST() { 　createXMLHttpRequest(); 　var url = " GetAndPostExample?timeStamp= " + new Date().getTime(); 　var queryString = createQueryString(); 　xmlHttp.open( " POST " , url, true ); 　xmlHttp.onreadystatechange = handleStateChange; 　xmlHttp.setRequestHeader( " Content-Type " , " application/x-www-form-urlencoded " ); 　xmlHttp.send(queryString); }

　　queryString就是名/值对的参数形式了（如name=LiLin&age=23）,在调用OPEN方法中，当请求方法是用POST的时候为了确保服务器知道请求体中有请求参数，需要调用setRequestHeader，将Content-Type值设置为application/x-www-form-urlencoded.当然也可不放在请求体中（那就不要用POST啦！）

　　此时server处理：

import java.io. * ; import java.net. * ; import javax.servlet. * ; import javax.servlet.http. * ; public class GetAndPostExample extends HttpServlet { 　protected void processRequest(HttpServletRequest request, HttpServletResponse response, String method) throws ServletException, IOException { 　　// Set content type of the response to text/xml 　　response.setContentType( " text/xml " ); 　　// Get the user's input 　　String firstName = request.getParameter( " firstName " ); 　　String middleName = request.getParameter( " middleName " ); 　　String birthday = request.getParameter( " birthday " ); 　　// Create the response text 　　String responseText = " Hello " + firstName + " " + middleName + " . Your birthday is " + birthday + " . " + " [Method: " + method + " ] " ; 　　// Write the response back to the browser 　　PrintWriter out = response.getWriter(); 　　out.println(responseText); 　　// Close the writer 　　out.close(); 　} 　protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 　　// Process the request in method processRequest 　　processRequest(request, response, " GET " ); 　} 　protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 　　// Process the request in method processRequest 　　processRequest(request, response, " POST " ); 　} }

　　对get and post方法都用processRequest来处理。

　　要向服务器发送相关复杂的查询串，可以将模型变化为XML发送到server 。

　　client端:

function createXML() { 　var xml = " <pets> " ; 　var options = document.getElementById( " petTypes " ).childNodes; 　var option = null ; 　for ( var i = 0 ; i < options.length; i ++ ) { 　　option = options[i]; 　　if (option.selected) { 　　　xml = xml + " <type> " + option.value + " <\/type> " ; 　　} 　} 　xml = xml + " <\/pets> " ; 　return xml; } function sendPetTypes() { 　createXMLHttpRequest(); 　var xml = createXML(); 　var url = " PostingXMLExample?timeStamp= " + new Date().getTime(); 　xmlHttp.open( " POST " , url, true ); 　xmlHttp.onreadystatechange = handleStateChange; 　xmlHttp.setRequestHeader( " Content-Type " , " application/x-www-form-urlencoded " ); 　xmlHttp.send(xml); }

　　createXML方法无非就是将内容以DOM的样式存到var xml（变量）里。有时也可能出现client直接将本地的一个XML文件直接以DOM（当然可以edit）的样式传送.(也放这个时个的Content-Type应该为text/xml了!)这时可能要用到ActiveXObject("MSXML2.DOMDocument.3.0")这样一个控件了。

　　关于这个控件有个方法可以在各broswer中通用的JS代码：

// -------------------------------------------------------------------- // Function: CreateXMLDOM // // Purpose: Creates a new XML DOM. // // Parameters: None // // Returns: XMLDOM object OR null // -------------------------------------------------------------------- function CreateXmlDOM() { 　var oXML = new ActiveXObject(GetXmlParserProgID()); 　try 　{ 　　oXML.setProperty( " AllowXsltScript " , true ); 　} 　catch (err) {} 　oXML.async = false ; 　oXML.validateOnParse = false ; 　oXML.resolveExternals = false ; 　oXML.setProperty( " SelectionLanguage " , " XPath " ); 　try {oXML.setProperty( " NewParser " , true );} catch (e) {} 　return oXML; } // -------------------------------------------------------------------- // Function: GetXmlParserProgID // // Purpose: // Gets the ProgID of the highest available version of the // Microsoft XML parser. // // Parameters: None // // Returns: String (i.e. "Msxml2.DOMDocument.4.0") // // -------------------------------------------------------------------- function GetXmlParserProgID() { 　var MAX_MAJOR_PARSER_VERSION = 10 ; 　var MIN_MAJOR_PARSER_VERSION = 0 ; 　var MAX_MINOR_PARSER_VERSION = 9 ; 　var MIN_MINOR_PARSER_VERSION = 0 ; 　var sProgID = g_sXmlParserProgID; 　var bFound = false ; 　if ( ! sProgID) 　{ 　　// Iterate through possible versions 　　for ( var nMajor = MAX_MAJOR_PARSER_VERSION; nMajor >= MIN_MAJOR_PARSER_VERSION; nMajor -- ) 　　{ 　　　for ( var nMinor = MAX_MINOR_PARSER_VERSION; nMinor >= MIN_MINOR_PARSER_VERSION; nMinor -- ) 　　　{ 　　　　// Set up the classname for the version that we're trying to instantiate 　　　　sProgID = " Msxml2.DOMDocument. " + nMajor + " . " + nMinor; 　　　　try 　　　　{ 　　　　　if ( new ActiveXObject(sProgID)) 　　　　　{ 　　　　　　bFound = true ; 　　　　　　break ; 　　　　　} 　　　　} 　　　　catch (e) 　　　　{} 　　　} 　　　if (bFound) 　　　{ 　　　　// store in a global variable to speedup subsequent calls 　　　　g_sXmlParserProgID = sProgID; 　　　　break ; 　　　} 　　} 　} 　return sProgID; }

　　然后直接用其load方法（本地）。

var xmlDoc = new ActiveXObject( " MSXML2.DOMDocument.3.0 " ); xmlDoc.load(local_XML_FileName);

　　当然也可以直接从server取来（用get方法即可），然后以responseText的方法

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); 　　} 　} }

　　实际上xmlDoc.loadXML(xmlht.responseText)所得到的就是一个于内存中的DOM了,而直接用responseXML的话就直接可以解析为一个DOM了!(注意load（FILE）与loadXML（DOM）是不同的)

　　此时servert process :

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(); } }

　　DOM,JDOM,JAXP随便你自己选好了！