MVC中控制层调用服务层的方法，方法有返回值，但是页面显示为空

orange_jli 2017-12-16 02:38:33

主要构想是从页面中用http session传输name这个值到控制层进行查询数据库操作，然后返回查询到的数据到B页面,B页面用session展示出来，现在AB页面都做好了，就是调用GETBYPORP方法不行，说我的值没有装载进对象。怎么办。

A页面

<#assign name='小米手机6' />

<input type="text" id="name" name="name" value=“${name}" hidden />

<input type="text" id="releaseTime" name="releaseTime"  hidden />

<input type="text" id="processor" name="processor"  hidden />

<input type="text" id="screenMaterial" name="screenMaterial"  hidden />

<input type="text" id="batteryCapacity" name="batteryCapacity"  hidden />

<input type="text" id="RAM" name="RAM"  hidden />

<input type="text" id="ROM" name="ROM"  hidden />

<input type="text" id="price" name="price"  hidden />

<input type="text" id="information" name="information"  hidden />

<script>

//    var i = 0;

    var btnSend =document.getElementById("send");

    btnSend.onclick = function () {

        var valname=document.getElementById("name").value;

        var valreleaseTime=document.getElementById("releaseTime").value;

        var valprocessor=document.getElementById("processor").value;

        var valscreenMaterial=document.getElementById("screenMaterial").value;

        var valbatteryCapacity=document.getElementById("batteryCapacity").value;

        var valRAM=document.getElementById("RAM").value;

        var valROM=document.getElementById("ROM").value;

        var valprice=document.getElementById("price").value;

        var valinformation=document.getElementById("information").value;

        var xmlhttp = new XMLHttpRequest();

        //        2  监控请求状态变化

        xmlhttp.onreadystatechange = function () {

            //            请求成功返回

            if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {

//                验证成功

                if (xmlhttp.responseText == "yes") {

                    alert("OK");

//                  跳转到详情页面

                    window.location.href = "/cs";

                } else {

                    alert("失败");

//                    info.innerHTML = "错误的账号或密码";

//                    info.style.color = "red";

                }

            }

        }

        //        3 设置请求参数

        xmlhttp.open("GET", "/goods/send?name="+ valname+ "&&releaseTime=" + valreleaseTime

                + "&&processor=" + valprocessor+ "&&screenMaterial=" + valscreenMaterial

                + "&&batteryCapacity=" + valbatteryCapacity+ "&&RAM=" + valRAM+ "&&ROM=" + valROM

                + "&&price=" + valprice+ "&&information=" + valinformation, true);

        //        4 异步请求

        xmlhttp.send(null);



    }

B页面





<#if Session["goods"]?exists>

${Session.goods.name!""}

${Session.goods.releaseTime!""}

${Session.goods.processor!""}

${Session.goods.screenMaterial!""}

${Session.goods.batteryCapacity!""}

${Session.goods.RAM!""}

${Session.goods.ROM!""}

${Session.goods.price!""}

</#if>

控制层



    @RequestMapping(value = "/send")

    @ResponseBody

    public String send(

                       @RequestParam String name,

                       @RequestParam String releaseTime,

                       @RequestParam String processor,

                       @RequestParam String screenMaterial,

                       @RequestParam String batteryCapacity,

                       @RequestParam String RAM,

                       @RequestParam String ROM,

                       @RequestParam String price,

                       @RequestParam String information,

                        HttpServletRequest request) {

        String flag = "no";

        Map map = new HashMap();  //new一个新集合来装载信息

        map.put("name", name);

        map.put("releaseTime", releaseTime);

        map.put("processor", processor);

        map.put("screenMaterial", screenMaterial);

        map.put("batteryCapacity", batteryCapacity);

        map.put("RAM", RAM);

        map.put("ROM", ROM);

        map.put("price", price);

        map.put("information", information);

        Goods goods = gs.getByProp(map);  //服务层的方法要返回值，否则goods值就为空

        if (goods != null) {

//            将对象写进session

            HttpSession session = request.getSession();

            session.setAttribute("goods", goods);

            flag = "yes";

        }

        return flag;

    }

方法



    public Goods getByProp(Map prop) {

           return igd.getByProp(prop);

    }

XML



    <select id="getByProp" resultType="com.example.demo.dto.Goods" parameterType="java.util.Map">

        SELECT

        <include refid="all"/>

        FROM

        <include refid="table"/>

        <where>

            <if test="name!=null">

                name=#{name}

            </if>

        </where>

    </select>

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