如何在Spring boot中将错误消息返回到输入页？

Question

我正在制作一个Spring启动的Web应用程序，我想处理唯一的键约束异常并将错误消息返回到输入页面。我已经搜索了很多这种方法，但没有找到。

控制器类：-

package com.ems.master.controller;

import java.sql.SQLIntegrityConstraintViolationException;

import javax.servlet.http.HttpSession;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.ems.master.dao.EnterpriseDao;
import com.ems.master.model.Enterprise;

@Controller
public class MasterController {

    @Autowired
    EnterpriseDao edao;

    @GetMapping("/")
    public String index() {
        return "Pages/index.html";
    }

    @RequestMapping("/Register")
    public String register() {
        return "Pages/AddEnterprise.html";
    }

    @RequestMapping("/AddEnterprise")
    @ExceptionHandler(SQLIntegrityConstraintViolationException.class)
    public String addEnterprise(ModelMap model, @RequestParam("entName") String entName,
            @RequestParam("entDesc") String entDesc, @RequestParam("owner") String owner,
            @RequestParam("contact") String contact, @RequestParam("code") String code,
            @RequestParam("contactNo") String contactNo, @RequestParam("contactEmail") String contactEmail) {
        try {
            Enterprise ent = new Enterprise();
            ent.setEnterpriseName(entName);
            ent.setEnterpriseDesc(entDesc);
            ent.setOwner(owner);
            ent.setContactPerson(contact);
            ent.setContactNo(code + "-" + contactNo);
            ent.setContactEmail(contactEmail);
            ent.setStatus("Active");
            edao.insert(ent);
            model.put("status", ent.getEnterpriseName() + " registered successfully.");
            return "Pages/Homepage.html";
        } catch (SQLIntegrityConstraintViolationException ex) {
            model.put("error", ex.getMessage());
            return "Pages/AddEnterprise.html";
        }
    }

}

请建议我做什么？

Answer 1

我认为您需要ReDirectAttie tes，请查看此链接：ReDirectAttie tes： addAtcm（）vs addFlashAtcm（）

@RequestMapping("/AddEnterprise")
    @ExceptionHandler(SQLIntegrityConstraintViolationException.class)
    public String addEnterprise(ModelMap model, @RequestParam("entName") String entName,
            @RequestParam("entDesc") String entDesc, @RequestParam("owner") String owner,
            @RequestParam("contact") String contact, @RequestParam("code") String code,
            @RequestParam("contactNo") String contactNo, @RequestParam("contactEmail") String contactEmail, RedirectAttributes redirectAttrs) {
        try {
            Enterprise ent = new Enterprise();
            ent.setEnterpriseName(entName);
            ent.setEnterpriseDesc(entDesc);
            ent.setOwner(owner);
            ent.setContactPerson(contact);
            ent.setContactNo(code + "-" + contactNo);
            ent.setContactEmail(contactEmail);
            ent.setStatus("Active");
            edao.insert(ent);
            model.put("status", ent.getEnterpriseName() + " registered successfully.");
            return "Pages/Homepage.html";
        } catch (SQLIntegrityConstraintViolationException ex) {

            redirectAttrs.addAttribute("error", ex.getMessage());

            return "redirect:/Register";
        }
    }