尝试使用 Thymeleaf 加载 HTML 文件时出现 Spring Boot 404

Question

正如标题所说，我在尝试访问 localhost:8080 时收到 Whitelabel 404 错误页面。

主类 :

package com.michaelLong.studentaddressbook;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

@SpringBootApplication
public class StudentAddressBookApplication extends SpringBootServletInitializer {

    public static void main(String[] args) {

        SpringApplication.run(StudentAddressBookApplication.class, args);
    }
}

pom.xml :

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.michaelLong</groupId>
    <artifactId>student-address-book</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>student-address-book</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Controller :

package controller;

import model.Student;
import model.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.ui.Model;
import java.util.Map;

@Controller
public class StudentController {

    @Autowired
    StudentRepository studentRepository;

    @GetMapping("/")
    public String showStudents(Model model){
        model.addAttribute("students", studentRepository.findAll());
        return "showStudents";
    }
}

application.properties :

spring.jpa.hibernate.ddl-auto=none
spring.datasource.url=jdbc:mysql://localhost:3306/StudentAddressBook
spring.datasource.username=root
spring.datasource.password=SQLpassword

showStudents.html :

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Student List</title>
</head>
<body>
<h2>List of students</h2>

<table>
    <tr>
        <th>Id</th>
        <th>First name</th>
        <th>Last name</th>
    </tr>
    <tr th:each="student: ${students}">
        <td th:text="${student.id}">Id</td>
        <td th:text="${student.firstName}">First name</td>
        <td th:text="${student.lastName}">Last name</td>
    </tr>

</table>
</body>
</html>

项目结构 :

src
|__main
   |__java
   |  |__com.example.studentaddressbook
   |  |  |__StudentAddressBookApplication
   |  |__controller
   |  |  |__StudentController
   |  |__model
   |     |__Student
   |     |__StudentRepository
   |__resources
      |__static
      |__templates
      |  |__showStudents.html
      |__application.properties

我试过看很多不同的教程，还有一些像这样的帖子:
Spring Boot and Thymeleaf: Can't find HTML templates & Why the html page doesn't get showed in thymeleaf?

我最初尝试使用 JSP，但我也无法使用它们。在这一点上，我觉得我的头撞在墙上，我不知道还能做什么。这是我第一次尝试使用 Spring Boot 和 Thymeleaf，所以我很难弄清楚这一点。

任何试图找出为什么我无法访问 HTML 页面的帮助将不胜感激。

Answer 1

您的 StudentAddressBookApplication 位于包“com.michaelLong.studentaddressbook”=> 它将仅扫描来自该父包的 bean。

StudentController 位于包“controller”=> 应用程序根本不会扫描它。

非常简单的解决方案:将 StudentController 移动到包 com.michaelLong.studentaddressbook。此外，这同样适用于 StudentRepository。

Java 中的 P.S 包总是小写的。