$.ajax({
        type:"POST",
        url:"/test.do",
        data:{},
        beforeSend:function(){},
        success: function(data){
            var obj=eval("("+data+")");
            if(obj.msg!=0){

                $("#tongzhi-content").html(obj.msg);
                $("#tongzhi").show();
            }else{
                $("#tongzhi").hide();
            }


        }
    });

@RequestMapping(value = "/test.do", method = RequestMethod.POST)
    private void doProcess(HttpServletRequest request
            , HttpServletResponse response) {
        StringBuffer json = new StringBuffer("{");
        int msgNum = 10;
        json.append("'msg':'" + msgNum + "'");
        json.append("}");//构造json数据格式
        System.out.println("json数据:"+json);
        try {
            PrintWriter out = response.getWriter();
            out.write(json.toString());

        } catch (IOException e) {
            e.printStackTrace();
        }

    }