【SSH】ERROR之Error setting expression 'id' with value ['1', ]

15:57:04.110 [http-nio-8080-exec-10] ERROR com.opensymphony.xwork2.interceptor.ParametersInterceptor - Unexpected Exception caught setting ‘id’ on 'class com.whpu.k16035.action.DishesAction: Error setting expression ‘id’ with value [‘12’, ]

/*
控制层
 */
public class DishesAction {
    //服务层
    private DishesService dishesService;
    private List<Dishes> dishesList;//传值
    //接受单条数据id
    private Integer id;
    //接收对象
    private Dishes dishes;
//    查询数据
    public String selectDishesAll(){
        dishesList = dishesService.selectDishesAll();//得到数据
        System.out.println(dishesList.toString());
        return "list";//跳转
    }
//    修改单条数据--先查询单条数据
    public String editDishesById(){
        System.out.println("调用service层的修改单条数据方法");
        dishes = dishesService.selectDishesById(id);
        System.out.println("得到了id"+dishes.getId());
//        跳转到编辑页面
        return "edit";
    }
    //保存修改的数据并--//重定向到查询全部的方法去
    public String saveDishes(){
        //（dao层通过hibernate更新到数据库）保存修改的数据
        dishesService.saveDishes(dishes);
        return "requert";//跳转到查询页面去更新数据
    }
//    ==================================================

    public DishesService getDishesService() {
        return dishesService;
    }

    public void setDishesService(DishesService dishesService) {
        this.dishesService = dishesService;
    }

    public List<Dishes> getDishesList() {
        return dishesList;
    }

    public void setDishesList(List<Dishes> dishesList) {
        this.dishesList = dishesList;
    }
}

操作当前jsp页面
<c:forEach items="${dishesList}" var="dishes">
            <tr>
                <td>${dishes.name}</td>
                <td><img src="${dishes.imgpath}" width="30px" height="30px" /></td>
                <td>${dishes.recipe}</td>
                <td>${dishes.types.type}</td>
                <td>${dishes.brief}</td>
                <td>${dishes.price}</td>
                <td>${dishes.sums}</td>
                <td>${dishes.priceAssociator}</td>
                <td>${dishes.sumsAssociator}</td>
                <td><a href="${pageContext.request.contextPath}/manage/dishesAction!editDishesById.action?id=${dishes.id}">修改</a></td>
                    <%--<a href="${pageContext.request.contextPath}/empAction!editPage.action?id=${emp.id}">修改</a>--%>
                <td><a href="${pageContext.request.contextPath}/DishesAction!">刪除</a></td>
            </tr>
            </c:forEach>

点击修改后想获取到id并且跳到修改单条数据的页面
于是报了上面那个错。
确定映射的名称没错后，再后台写了个输出语句，发现action的 editDishesById方法不能成功调用。说明href="$pageContext.request.contextPath/manage/dishesAction!editDishesById.action?id=${dishes.id}">修改没有获取到吧
反反复复找了很久，发现action类中的id和dishes没有写get、set方法。
写了get、set后发现成功了。