在浏览器中，我无法获得引导表，而是出现白标错误

【问题标题】：In browser i couldn't get Boot Strap tables instead i get white label error在浏览器中，我无法获得引导表，而是出现白标错误
【发布时间】：2021-09-09 07:40:26
【问题描述】：

在之前的 Spring Boot 中，我创建了包含 4 列的员工管理系统表 -> 名称、姓氏、电子邮件和操作列，其中包含更新和删除按钮。现在，我添加了额外的 3 列 -> 性别、生日、技能。一切正常，没有编译错误和控制台错误，但是当我点击浏览器时，我得到了 whitelabel 错误。谁能给我一个解决这个问题的方法。

1.Employee Entity.Class

package com.employee.entity;

import java.util.Date;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "employees")
public class Employee 
{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String firstname;
    private String lastname;
    private String email;
    
    private String gender;
    private Date birthday;
    private String skill;
    
    public Employee() {
        
    }
    
        public Employee(long id, String firstname, String lastname, String email, String gender, Date birthday,
            String skill) {
        super();
        this.id = id;
        this.firstname = firstname;
        this.lastname = lastname;
        this.email = email;
        this.gender = gender;
        this.birthday = birthday;
        this.skill = skill;
    }


    public String getFirstname() {
        return firstname;
    }
    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }



    public String getLastname() {
        return lastname;
    }
    public void setLastname(String lastname) {
        this.lastname = lastname;
    }



    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }



    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }



    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }



    public String getSkill() {
        return skill;
    }
    public void setSkill(String skill) {
        this.skill = skill;
    }
}

2.EmployeeController.class

package com.employee.controller;


import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;

import com.employee.entity.Employee;
import com.employee.service.EmployeeService;

@Controller // Controller Layer holds all Spring MVC Controllers
public class EmployeeController 
{
    private EmployeeService employeeService;

    public EmployeeController(EmployeeService employeeService) {
        super();
        this.employeeService = employeeService;
    }
    
    @GetMapping("/employees")
    public String listEmployess(Model model)
    {
        model.addAttribute("employees", employeeService.getAllEmployees());
        return "employees";
    }
    
    @GetMapping("/employees/new")
    public String createEmployeeForm(Model model)
    {
        //Create empty employee object to hold employee form data
        Employee employee = new Employee();
        
        model.addAttribute("employee", employee);
        return "create_employee";
    }
    
    @PostMapping("/employees")
    public String saveEmployee(@ModelAttribute("employee") Employee employee)
    {
        employeeService.saveEmployee(employee);
        return "redirect:/employees";
    }
    
    @GetMapping("/employees/edit/{id}")
    public String editEmployeeForm(@PathVariable Long id, Model model)
    {
        model.addAttribute("employee", employeeService.getEmployeeById(id));
        return "edit_employee";
    }
    
    @PostMapping("/employees/{id}")
    public String updateEmployee(@PathVariable Long id, @ModelAttribute("employee") Employee employee, Model model)
    {
        // get employee from database by id
        Employee existingEmployee = employeeService.getEmployeeById(id);
        //existingEmployee.setId(id);
        existingEmployee.setFirstname(employee.getFirstname());
        existingEmployee.setLastname(employee.getLastname());
        existingEmployee.setEmail(employee.getEmail());
        existingEmployee.setGender(employee.getGender());
        existingEmployee.setBirthday(employee.getBirthday());
        existingEmployee.setSkill(employee.getSkill());
        
        // save updated employee object
        employeeService.updateEmployee(existingEmployee);
        return "redirect:/employees";
    }
    
    @GetMapping("/employees/{id}")
    public String deleteEmployee(@PathVariable Long id)
    {
        employeeService.deleteEmployeeById(id);
        return "redirect:/employees";
    }
}

3.EmployeeRepository.interface

package com.employee.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import com.employee.entity.Employee;

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long>
{

}

4.EmployeeService.interface

package com.employee.service;

import java.util.List;

import com.employee.entity.Employee;

public interface EmployeeService 
{
    public List<Employee> getAllEmployees();
    
    Employee saveEmployee(Employee employee);
    
    Employee getEmployeeById(Long id);
    
    Employee updateEmployee(Employee employee);
    
    void deleteEmployeeById(Long id);
}

5.EmployeeServiceImpl.class

package com.employee.service.impl;

import java.util.List;

import org.springframework.stereotype.Service;

import com.employee.entity.Employee;
import com.employee.repository.EmployeeRepository;
import com.employee.service.EmployeeService;

@Service
public class EmployeeServiceImpl implements EmployeeService 
{
    private EmployeeRepository employeeRepository;
    
    public EmployeeServiceImpl(EmployeeRepository employeeRepository) {
        super();
        this.employeeRepository = employeeRepository;
    }

    @Override
    public List<Employee> getAllEmployees() 
    {
        return employeeRepository.findAll();
    }

    @Override
    public Employee saveEmployee(Employee employee) 
    {
    
        return employeeRepository.save(employee);
    }

    @Override
    public Employee getEmployeeById(Long id) {
        
        return employeeRepository.findById(id).get();
    }

    @Override
    public Employee updateEmployee(Employee employee) {
        
        return employeeRepository.save(employee);
    }

    @Override
    public void deleteEmployeeById(Long id) 
    {
        employeeRepository.deleteById(id);
        
    }
}

6.application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/ems?useSSL=false&serverTime=UTC&useLegacyDatetimeCode=false
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=1441
server.port=8097

#spring.jpa.database-platform = org.hibernate.dialect.MySQL5Dialect
#spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect

spring.thymeleaf.check-template=true
spring.thymeleaf.check-template-location=true
spring.thymeleaf.enabled=true
spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.suffix=.html

spring.jpa.generate-ddl=true
spring.jpa.hibernate.ddl-auto=update

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect

debug=true
logging.level.org.hibernate.SQL=DEBUG
#logging.level.<package_name>=<LOGGING_LEVEL>
#logging.level.org.springframework.context=DEBUG

spring.profiles.active=@spring.profiles.active@
spring.jpa.open-in-view=false
logging.level.org.springframework.boot.autoconfigure=ERROR

7.employees.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
<link rel="stylesheet" 
      href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" 
      integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" 
      crossorigin="anonymous">
</head>
<body>

<nav class="navbar navbar-expand-md bg-dark navbar-dark">
  <!-- Brand -->
  <a class="navbar-brand" href="#">Employee Management System</a>

  <!-- Toggler/collapsibe Button -->
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#collapsibleNavbar">
    <span class="navbar-toggler-icon"></span>
  </button>

  <!-- Navbar links -->
  <div class="collapse navbar-collapse" id="collapsibleNavbar">
    <ul class="navbar-nav">
      <li class="nav-item">
        <a class="nav-link" th:href="@{/employees}">Employee Management</a>
      </li>
    </ul>
  </div>
</nav>

    <div class ="container">
        <div class = "row">
            <h1> List Employees </h1>
        </div>
        
        <div class = "row" >
            <div class = "col-lg-3">
                <a th:href = "@{/employees/new}" class = "btn btn-primary btn-sm mb-3"> Add Employee</a>
            </div>
        </div>
        
        <table class = "table table-striped table-bordered" >
            <thead class = "table-dark">
                <tr>
                    <th> Employee First Name </th>
                    <th> Employee Last Name </th>
                    <th> Employee Email </th>
                    <th> Employee Gender </th>
                    <th> Employee Birthday </th>
                    <th> Employee Skill </th>
                    <th> Actions </th>
                </tr>
            </thead>
            
            <tbody>
                <tr th:each = "employee : ${employees}">
                    <td th:text = "${employee.firstname}"></td>
                    <td th:text = "${employee.lastname}"></td>
                    <td th:text = "${employee.email}"></td>
                    <td th:text = "${employee.gender}"></td>
                    <td th:text = "${employee.birthday}"></td>
                    <td th:text = "${employee.skill}"></td>
                    
                    <td>
                        <a th:href = "@{/employees/edit/{id}(id=${employee.id})}"
                        class = "btn btn-primary">Update</a>
                        
                        <a th:href = "@{/employees/{id}(id=${employee.id})}"
                        class = "btn btn-danger">Delete</a>
                    </td>
                </tr>
            </tbody>
        </table>
    </div>

</body>
</html>

8.create_employee.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="ISO-8859-1">
<title>Employee Management System</title>
<link rel="stylesheet" 
      href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" 
      integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" 
      crossorigin="anonymous">
</head>
<body>

<nav class="navbar navbar-expand-md bg-dark navbar-dark">
  <!-- Brand -->
  <a class="navbar-brand" href="#">Employee Management System</a>

  <!-- Toggler/collapsibe Button -->
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#collapsibleNavbar">
    <span class="navbar-toggler-icon"></span>
  </button>

  <!-- Navbar links -->
  <div class="collapse navbar-collapse" id="collapsibleNavbar">
    <ul class="navbar-nav">
      <li class="nav-item">
        <a class="nav-link" th:href="@{/employees}">Employee Management</a>
      </li>
    </ul>
  </div>
</nav>

<br>
<br>
    
    <div class = "container">
        <div class = "row">
            <div class = "col-lg-6 col-md-6 col-sm-6 container justify-content-center-center card">
                <h1 class = "text-center"> Create New Employee </h1>
                <div class = "card-body" >
                    <form th:action="@{/employees}" th:object = "${employee}" method="POST">
                        <div class = "form-group">
                            <label> Employee First Name </label>    
                            <input
                            type = "text"
                            name = "firstname"
                            th:field = "*{firstname}"
                            class = "form-control"
                            placeholder = "Enter Employee First Name"
                            />                  
                        </div>  
                        
                        <div class = "form-group">
                            <label> Employee Last Name </label> 
                            <input
                            type = "text"
                            name = "lastname"
                            th:field = "*{lastname}"
                            class = "form-control"
                            placeholder = "Enter Employee Last Name"
                            />                  
                        </div>
                        
                            <div class = "form-group">
                            <label> Employee Email </label> 
                            <input
                            type = "text"
                            name = "email"
                            th:field = "*{email}"
                            class = "form-control"
                            placeholder = "Enter Employee Email"
                            />                  
                        </div>  
                        
                        <div class = "form-group">
                            <label>  Employee Gender </label>
                            <input type="radio" th:field="*{gender}" value="Male" />Male
                            <input type="radio" th:field="*{gender}" value="Female" />Female
                            <input
                            type = "radio"
                            name = "gender"
                            th:field = "*{gender}"
                            class = "form-control"
                            />
                        </div>
                        
                        <div class = "form-group">
                            <label> Employee Birthday </label>
                            <input type="date" th:field="*{birthday}" />
                            <input
                            type = "date"
                            name = "birthday"
                            th:field = "*{birthday}"
                            class = "form-control"
                            />
                        </div>
                        
                        <div class = "form-group">
                            <label> Employee Skill </label> 
                            <input
                            type = "text"
                            name = "skill"
                            th:field = "*{skill}"
                            class = "form-control"
                            placeholder = "Enter Employee Skill"
                            />                  
                        </div>  
                        
        
                        <div class = "box-footer">
                            <button type="submit" class = "btn btn-primary">
                                Submit
                            </button>
                        </div>
                    </form>
                </div>
            </div>
        </div>
    </div>



</body>
</html>

9.edit_employee.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="ISO-8859-1">
<title>Employee Management System</title>
<link rel="stylesheet" 
      href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" 
      integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" 
      crossorigin="anonymous">
</head>
<body>

<nav class="navbar navbar-expand-md bg-dark navbar-dark">
  <!-- Brand -->
  <a class="navbar-brand" href="#">Employee Management System</a>

  <!-- Toggler/collapsibe Button -->
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#collapsibleNavbar">
    <span class="navbar-toggler-icon"></span>
  </button>

  <!-- Navbar links -->
  <div class="collapse navbar-collapse" id="collapsibleNavbar">
    <ul class="navbar-nav">
      <li class="nav-item">
        <a class="nav-link" th:href="@{/employees}">Employee Management</a>
      </li>
    </ul>
  </div>
</nav>

<br>
<br>
    
    <div class = "container">
        <div class = "row">
            <div class = "col-lg-6 col-md-6 col-sm-6 container justify-content-center-center card">
                <h1 class = "text-center"> Create New Employee </h1>
                <div class = "card-body" >
                        <form th:action="@{/employees/{id} (id=${employee.id})}" th:object = "${employee}" method="POST">
                        <div class = "form-group">
                            <label> Employee First Name </label>    
                            <input
                            type = "text"
                            name = "firstname"
                            th:field = "*{firstname}"
                            class = "form-control"
                            placeholder = "Enter Employee First Name"
                            />                  
                        </div>  
                        
                        <div class = "form-group">
                            <label> Employee Last Name </label> 
                            <input
                            type = "text"
                            name = "lastname"
                            th:field = "*{lastname}"
                            class = "form-control"
                            placeholder = "Enter Employee Last Name"
                            />                  
                        </div>  
                        
                        <div class = "form-group">
                            <label> Employee Email </label> 
                            <input
                            type = "text"
                            name = "email"
                            th:field = "*{email}"
                            class = "form-control"
                            placeholder = "Enter Employee Email"
                            />                  
                        </div>  
                        
                        <div class = "form-group">
                            <label>  Employee Gender </label>
                            <input type="radio" th:field="*{gender}" value="Male" />Male
                            <input type="radio" th:field="*{gender}" value="Female" />Female
                            <input
                            type = "radio"
                            name = "gender"
                            th:field = "*{gender}"
                            class = "form-control"
                            />
                        </div>
                        
                        <div class = "form-group">
                            <label> Employee Birthday </label>
                            <input type="date" th:field="*{birthday}" />
                            <input
                            type = "date"
                            name = "birthday"
                            th:field = "*{birthday}"
                            class = "form-control"
                            />
                        </div>
                        
                        <div class = "form-group">
                            <label> Employee Skill </label> 
                            <input
                            type = "text"
                            name = "skill"
                            th:field = "*{skill}"
                            class = "form-control"
                            placeholder = "Enter Employee Skill"
                            />                  
                        </div>  
                        
                        
                        <div class = "box-footer">
                            <button type="submit" class = "btn btn-primary">
                                Submit
                            </button>
                        </div>
                    </form>
                </div>
            </div>
        </div>
    </div>



</body>
</html>

【问题讨论】：

  • 能否分享一下 GitHub 链接，以便我在本地机器上轻松测试？
  • 什么端点的白标错误？
  • link@UbaidurRehman
  • 此应用程序没有明确的 /error 映射，因此您将其视为后备。 @deepakchethan

标签： spring-boot bootstrap-4 thymeleaf


【解决方案1】：

您只需为/ 添加映射，它将重定向到登录页面（在您的情况下为employees 页面）。

所以，只需在您的 EmployeeController 中添加以下 GET 映射

    @GetMapping('/')
    public String index() {
        return "redirect:/employees";
    }

【讨论】：

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