1.ajaxRequest.js

function createRequest(url,number) {
	    http_request = false;
	    if (window.XMLHttpRequest) {    							   // 非IE浏览器
	        http_request = new XMLHttpRequest();	                      //创建XMLHttpRequest对象
	    } else if (window.ActiveXObject) {     						   // IE浏览器
	        try {
	            http_request = new ActiveXObject("Msxml2.XMLHTTP");	   //创建XMLHttpRequest对象
	        } catch (e) {
	            try {
	                http_request = new ActiveXObject("Microsoft.XMLHTTP");  //创建XMLHttpRequest对象
	           } catch (e) {}
	        }
	    }
	    if (!http_request) {
	        alert("不能创建XMLHttpRequest对象实例！");
	        return false;
	    }
	    //调用返回结果处理函数
	    if(number==1)
	    	//回调函数
	    	http_request.onreadystatechange = getResult;
	    http_request.open('GET',url,true);
	    //创建与服务器的连接
	    //true异步提交请求
	    //false同步提交请求
	    http_request.send(null);
	   //发送请求：实体内容
}
function getResult(){
	//alert(n);
	//alert(http_request.responseText);
	//0初始化1正在加载2已加载3交互中4完成
	if(http_request.readyState==4){
		if(http_request.status=200){
			document.getElementById("pid_tooltip").innerHTML=http_request.responseText;
		}else {
			alert("您所请求的页面错误！");
		}
	}
}
function pid_tooltip_check(){	
	createRequest('Do?action=pid_tooltip_ask-receipt&pid='+document.getElementById("idnumber").value,1);
}

当包含特殊字符时，如下处理：

createRequest('Do?action=pid_tooltip_ask-receipt&pid='+escape(document.getElementById("idnumber1").value),7);

Post请求方式：

http_request.open("POST","Do?action=pid_tooltip_ask-receipt",true);
	    http_request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
	    http_request.send("pid="+escape(document.getElementById("idnumber1").value));

Servlet

/*
	 * 身份证合法性检测
	 */
	protected void pid_tooltip(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
		// TODO Auto-generated method stub
		String pid=request.getParameter("pid")==null?"":request.getParameter("pid");//身份证
		String mes="";		
		//System.out.println(pid);
		//18位
		if(pid.length()!=18){
			//身份证必须是18位
			//response.sendRedirect("ask-receipt.jsp?flag=121");
			//mes="<font color=red>身份证必须是18位</font>";
			mes="<font color=red>×</font>";
			cf.pid_correct=false;
		}
		else{
			PidCheck pc=new PidCheck();			
			if(pc.check_(pid)){
				//身份证输入正确
				//mes="<font color=green>身份证正确</font>";
				mes="<font color=green>√</font>";
				cf.pid_correct=true;
			}else{
				//身份证输入有误
				//mes="<font color=red>身份证有误!请重新输入</font>";
				mes="<font color=red>×</font>";
				cf.pid_correct=false;
			}
		}
		//System.out.println(cf.pid_correct);
		//System.out.println(mes);
		response.setContentType("text/html");
		response.setCharacterEncoding("UTF-8");
		response.setHeader("Cache-Control","no-store");//http1.1不缓存
		response.setHeader("Pragma","no-cache");//http1.0不缓存
		response.setDateHeader("Expires",0);//阻止从代理服务器获取
		PrintWriter out=response.getWriter();
		out.println(mes);
		//System.out.println(mes);
		out.flush();
		out.close();		
	}