Ajax通过post方法向Servlet提交信息

<script type="text/javascript">
            var req;
			var content = "id=123&name=gavin&address=WorshintonDC.USA";
            function validate() {
                
                //创建一个XMLHttpRequest对象req
                if(window.XMLHttpRequest) {
                    //IE7, Firefox, Opera支持
                    req = new XMLHttpRequest();
                }else if(window.ActiveXObject) {
                    //IE5,IE6支持
                    req = new ActiveXObject("Microsoft.XMLHTTP");
                }
               
                req.open("post", url, true);
                req.setRequestHeader("Content-Type","application/x-www-form-urlencoded");                
                req.onreadystatechange = callback;
                //send函数发送请求，参数
                req.send(content);
            }
</script>

 在servlet中：

	response.setContentType("text/html");
    response.setHeader("Cache-Control", "no-store");
    response.setHeader("Pragma", "no-cache");
    response.setDateHeader("Expires", 0);
    String put = null;
    for(Enumeration<String> e = request.getParameterNames(); e.hasMoreElements(); ) {
                String h = (String) e.nextElement();
                String c = (String)request.getParameter(h);
                put += c;                                
    }
	out.write("message is:" + put);