ajax提交一个包含list的实体

/**
 * 添加
 */
function insertPsas() {
    var psasName = $('#psasName').val();
    if(materials[0]==null){
        layer.alert("请选择视频!");
        return;
    }else if(materials[1]==null || materials[2]==null){
        layer.alert("请选择图片!");
        return;
    }
    $.ajax({
        url : ctx + '/psas/insertPsas',
        data : "{\"psasName\":\""+psasName+"\",\"materialList\":"+JSON.stringify(materials)+"}",        
        type : 'post',
        async : true,
        dataType : "json",
        contentType: "application/json",
        success : function(data) {
            if (data.msg == '00') {
                queryDevice();
                layer.alert('提交成功!', {
                    icon : 1,
                    skin : 'layer-ext-moon'
                });
            } else if (data.msg == '02') {
                layer.alert('提交失败!', {
                    icon : 2,
                    skin : 'layer-ext-moon'
                });
            }
        }
    });
}

    @UserAnnotation(methodName = "添加公益广告", markName = "order.psas.insertPsas")
    @RequestMapping(value = "/insertPsas", method = { RequestMethod.POST, RequestMethod.GET })
    public  void insertPsas(HttpServletRequest request, HttpServletResponse response,@RequestBody Psas psas) throws Exception {
        JSONObject jsonObject = new JSONObject();
        try {
            psas.setTemplateId(3L);
            psas.setCreateTime(DateUtil.getCurrDateTime());
            psas.setValid(1);
            psas.setVersion(1L);
            this.psasService.insertPsas(psas);
            msg = Constants.SCUUESS;
        } catch (Exception e) {
            log.error("insertDevice:" + e);
            msg = Constants.FAIL;
        }
        jsonObject.accumulate("msg", msg);
        responseSendMsg(response, jsonObject.toString());
    }

xml
<bean id="mappingJackson2HttpMessageConverter"
        class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8</value>
                <value>application/json</value>
                    <!--自定义处理MediaType-->
                    <value>text/json</value>
            </list>
        </property>
    </bean>

实体
public class Psas extends BaseModel {

        private Long id;
    
        private List<Material> materialList;
        
        public List<Material> getMaterialList() {
            if (materialList == null) {
                materialList = new ArrayList<Material>();
            }
            return materialList;
        }

        public void setMaterialList(List<Material> materialList) {
            this.materialList = materialList;
        }
}