错误/ BindingResult的说法，预计(Errors/BindingResult argum

我学习Spring MVC和我试图验证表单。当用户搜索一个空字符串，它会显示错误。当我执行我的代码，我得到以下错误

一个错误/ BindingResult参数预计模型在控制器方法签名属性参数之后立即：公共java.lang.String中com.mycompany.controller.catalog.SearchController.search（javax.servlet.http.HttpServletRequest，的javax.servlet .http.HttpServletResponse，java.lang.String中，org.springframework.validation.BindingResult，org.springframework.ui.Model）抛出javax.servlet.ServletException，java.io.IOException的，org.broadleafcommerce.common.exception.ServiceException

package com.mycompany.controller.catalog;

import org.broadleafcommerce.common.exception.ServiceException;

import org.broadleafcommerce.core.web.controller.catalog.Mysearchcontroller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import  org.springframework.web.method.support.ModelAndViewContainer;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

@Controller
@RequestMapping("/search")
public class SearchController extends Mysearchcontroller {


    @RequestMapping("")
    public String search(HttpServletRequest request, HttpServletResponse response,
            @RequestParam(value = "q") String q,BindingResult errors,Model model) throws ServletException, IOException, ServiceException {
        return search3(model, request,response, q ,errors);
    }

}

Answer 1:

所述BindingResult参数只能在一起选择使用具有@ModelAttribute注解的方法。如果没有模型属性也将是没有约束力的，因此没有BindingResult实例将是可用的。所以你的情况，你必须删除BindingResult说法，因为它永远不会在你的情况下工作，由于缺乏一个模型属性的。

模型属性不一样的Model （如被暗示上）。该模型的属性是部分Model 。

Answer 2:

如果q是可选的修改@RequestParam(value = "q") 串 Q (@RequestParam(required = false) String q

 @RequestMapping("")
 public String search(HttpServletRequest request, HttpServletResponse response,
        (@RequestParam(required = false) String q,BindingResult errors,Model model) throws ServletException, IOException, ServiceException {
        return search3(model, request,response, q ,errors);
 }