前后台交互

1. 前台向后台传值

　　提交form表单

<form id="sb" action="${pageContext.request.contextPath }/admin/loanContract/addOrUpdate.do" method="post">

　　各种输入框各种值

　　<button class="tjbtn" id="sbm">提 交</button></form>

　用form提交有个问题就是：提交到后台后，成功后，后台跳转页面只能跳到响应的页面了，但是想要保留在本页面并且弹出alert，就只能这种方法，应该加上@ResponseBody

@RequestMapping("updateSelfdomNeed")
@ResponseBody
    public void updateSelfdomNeed(HttpServletRequest request,HttpServletResponse response){
        String textArea = request.getParameter("textArea");
        String wishId = request.getParameter("wishId");
        int count = selfdomNeedService.updateSelfNeed(wishId,textArea);
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = null;
        try {
            out = response.getWriter();
            if(count>0){
                out.print("<script>alert('处理成功!');"
                        + "location.href='/CarExchange/admin/selfdomNeed/selfdomNeedList.do';</script>  ");
            }
            else{
                out.print("<script>alert('处理失败!');location.href='/CarExchange/admin/selfdomNeed/selfdomNeedList.do';</script>  ");
            out.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

　js中用ajax

$("#sbm").click(function(){
        var sp = $("#sp").html(); 
        
        if(sp!='交易订单已存在！'){
            $("#sb").submit();
            return;
        }
        
        alert('交易订单已存在或为空!');
        return;
    });
    
    $("#tradeCode").blur(function(){
        
        var tradeCode = $("#tradeCode").val();
        
        $.ajax({
            url:"checkTradeCode.do",
            data:{tradeCode:tradeCode},
            dataType:"json",
            success:function(data){
                var arr = eval(data);
                $("#sp").html(arr.code);
            }
        });
        
    });

　　url传值

<c:if test="${result.status eq 3}">
                                        <input type="hidden" value="${result.status }" name="status" id ="status"/>
                                        <input type="button" name="" class="majoBtn" onclick="location.href='${pageContext.request.contextPath }/admin/orderpayment/payviewshow.do?orderCode=${result.orderCode}&paySource=2'" value="支付尾款">
                                        <span class="txtdec fs10 open">
                                               <a href="javascript:void(0)" id="" onclick="orderDetails(${result.orderCode })" title="查看详情" class="" >查看详情</a>
                                        </span>
                                        <span class="txtdec fs10 open">
                                            <a href="javascript:void(0)" onclick="CancelOrder(${result.orderCode })" title="取消订单" class="">取消订单</a>
                                        </span>
                                    </c:if>



function CancelOrder(orderCode){
        var status = $("#status").val();//按id取值
        if (confirm("是否取消订单？")) {
            window.location.href ="../order/CancelOrder.do?orderCode="+orderCode+"&status="+status;
        }
    }

　　前台从url路径上获得值

GetQueryString :function(name) {
           var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)","i");
           var r = window.location.search.substr(1).match(reg);
           if (r!=null) return (r[2]); return null;
        },


var carId = frontLogin.GetQueryString("carId");