ajax发XML给Struts,Struts收不到？该怎么解决

ajax发XML给Struts,Struts收不到？？
在struts的action应用  
request.setCharacterEncoding( "UTF-8 ");  
BufferedReader   reader   =   request.getReader();  
boolean   is   =   false;  
while   ((line   =   reader.readLine())   !=   null)   {  
is   =   true;  
}  
结果System.out.println(is);打印结果为false，不知其中缘由，传说request.getReader();方法只能调用一次  
但是呢，一个简单的例子就能成功，如下：  
Servlet> > >  
package   servlet;  

import   java.io.BufferedReader;  
import   java.io.ByteArrayInputStream;  
import   java.io.IOException;  
import   java.io.PrintWriter;  

import   javax.servlet.ServletException;  
import   javax.servlet.http.HttpServlet;  
import   javax.servlet.http.HttpServletRequest;  
import   javax.servlet.http.HttpServletResponse;  
import   javax.xml.parsers.DocumentBuilderFactory;  
import   javax.xml.parsers.ParserConfigurationException;  

import   org.w3c.dom.Document;  
import   org.xml.sax.SAXException;  

public   class   TestServlet   extends   HttpServlet   {  

/**  
*   Constructor   of   the   object.  
*/  
public   TestServlet()   {  
super();  
}  

/**  
*   Destruction   of   the   servlet.   <br/>  
*/  
public   void   destroy()   {  
super.destroy();   //   Just   puts   "destroy "   string   in   log  
//   Put   your   code   here  
}  
public   void   doGet(HttpServletRequest   request,   HttpServletResponse   response)  
throws   ServletException,   IOException   {  

this.doPost(request,   response);  
}  

public   void   doPost(HttpServletRequest   request,   HttpServletResponse   response)  
throws   ServletException,   IOException   {  
request.setCharacterEncoding( "UTF-8 ");  
System.out.println( "Ajax   Start...... ");  
String   name   =   "no ";  
String   password   =   "00 ";  
/**  
*   读取xml格式的参数  
*/  
StringBuffer   readXml   =   new   StringBuffer();  
String   line   =   null;  
boolean   is   =   false;  
try   {  
BufferedReader   reader   =   request.getReader();  
while   ((line   =   reader.readLine())   !=   null)   {  
readXml.append(line);  
is   =   true;  
}  
}   catch   (Exception   e)   {  
System.out.println(e.toString());  
}  
if   (is)   {  
String   xml   =   readXml.toString();  
Document   xmlDoc   =   null;  
try   {  
xmlDoc   =   DocumentBuilderFactory.newInstance()  
.newDocumentBuilder().parse(  
new   ByteArrayInputStream(xml.getBytes()));  
}   catch   (ParserConfigurationException   e)   {  
System.out.println( "ParserConfigurationException ");