ajax serlvet示例

前台：
<script type="text/javascript" language="javascript">
  var xml;
  function createXml(){
  if(window.XMLHttpRequest){
  xml=new XMLHttpRequest();
  }else if(window.ActionXObject){
  xml=new ActionXObject("Microsoft.XMLHTTP");
  }
  }
  function test(){
  createXml();
  var name="xcl";
  var url="testServlet.do?name="+name;
  xml.open("GET",url);
  xml.onreadystatechange=callback;
  xml.send(null);
  }
  function callback(){
  if(xml.readyState==4&&xml.status==200){
  //alert("1111");
  var name=xml.responseText;
  alert(name);
  }
  }
  </script>


配置文件：
<servlet>
  <servlet-name>test</servlet-name>
  <servlet-class>com.servlet.UserServlet</servlet-class>
  </servlet>
  <servlet-mapping>
  <servlet-name>test</servlet-name>
  <url-pattern>/testServlet.do</url-pattern>
  </servlet-mapping>


后台：


public class UserServlet extends HttpServlet{


@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
//super.doGet(req, resp);
String name=req.getParameter("name");
name=name+"---return;sky";
PrintWriter out=resp.getWriter();
out.print(name);
}

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
//super.doPost(req, resp);
this.doGet(req, resp);
}
}




2通过后台直接传json对象，前台也可以通过responseText来得到，
如：if(xml.readyState==4&&xml.status==200){
  //alert("1111");
  var name=xml.responseText;
  //var name1={a:'a1'};
  //var jsonObject2=JSON.stringify(eval("("+name+")"));
  //alert(jsonObject2.a);
  //alert(name);
  var jsonObject1=eval("("+name+")");
 
  alert(jsonObject1.a+"---"+jsonObject1.b+"----"+jsonObject1.c);
  var jsonObject3=JSON.stringify(jsonObject1);
  alert(jsonObject3);
  }
后台：
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
//super.doGet(req, resp);
String name=req.getParameter("name");
name=name+"---return;sky";
String json="{a:'a1',b:'b1',c:'c1'}";
JSONObject jsonObject=JSONObject.fromObject(json);

PrintWriter out=resp.getWriter();
out.print(jsonObject);
}