尝试呈现index.html时，Spring Boot + Thymeleaf =“ Whitelabel错误页面”

Question

我正在尝试做简单的Spring MVC库

您是否知道为什么我的View有问题，当我在控制器中使用主页方法时，应该向我显示index.html，但我一直都只收到Whitelabel Error Page，而我不知道为什么：/

我的结构：[ https://i.imgur.com/5TrGGrB.png]

我的控制器：

package controller;


import model.Book;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
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.RequestMethod;
import org.springframework.web.servlet.ModelAndView;
import service.BookService;

import javax.servlet.http.HttpServletRequest;
import java.util.List;


@Controller
public class LiberianController{

    @Autowired
    private BookService bookService;


    @RequestMapping(value = "/")
    public String homepage() {
        return "index";
    }

    @GetMapping(value = "/allBooks")
    public ModelAndView allBooks(ModelAndView modelAndView) {
        List<Book> books = bookService.getAllBooks();
        modelAndView.addObject("listBooks", books);
        modelAndView.setViewName("allBooks");

        return modelAndView;
    }

    @GetMapping(value = "/addBook")
    public ModelAndView newBook(ModelAndView modelAndView) {
        Book book = new Book();
        modelAndView.addObject("book", book);
        modelAndView.setViewName("addBook");
        return modelAndView;
    }

    @GetMapping(value = "updateBook")
    public ModelAndView updateBook(HttpServletRequest httpServletRequest) {
        long id = Long.parseLong(httpServletRequest.getParameter("id"));
        Book book = bookService.getBook(id);
        ModelAndView modelAndView = new ModelAndView("addBook");
        modelAndView.addObject("book", book);
        return modelAndView;
    }

    @RequestMapping(value = "/saveBook",method = RequestMethod.POST)
    public ModelAndView saveBook(@ModelAttribute Book book) {

        if (book.getId() == 0) {
            bookService.addBook(book);

        } else {
            bookService.updateBook(book.getId(), book);
        }
        return new ModelAndView("redirect:/allBooks");
    }

    @GetMapping(value = "/deleteBook")
    public ModelAndView deleteBook(HttpServletRequest httpServletRequest) {
        long id = Long.parseLong(httpServletRequest.getParameter("id"));
        bookService.deleteBook(id);
        return new ModelAndView("redirect:/allBooks");
    }





}

我的POM：

<?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>MyLibrary</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.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-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

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

        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.2.12.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.thymeleaf/thymeleaf -->
        <dependency>
            <groupId>org.thymeleaf</groupId>
            <artifactId>thymeleaf</artifactId>
            <version>3.0.9.RELEASE</version>
        </dependency>

    </dependencies>

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


</project>

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Something</title>
</head>
<body>
<h1>Hello</h1>

</body>
</html>

aplication.properties

spring.jpa.hibernate.ddl-auto=update
spring.datasource.url=jdbc:mysql://localhost:3306/book?useSSL=false
spring.datasource.username=root
spring.datasource.password=root


spring.mvc.view.prefix=/WEB-INF/
spring.mvc.view.suffix=.jsp

spring.thymeleaf.mode=LEGACYHTML5

Answer 1

您的演示项目有一些问题。

1.包装结构不正确

您将您的Runner课程放入默认程序包。这不是一个好主意，因为在这种情况下，Spring Boot无法为组件扫描设置默认软件包。运行应用程序时，您应该看到类似以下内容的信息：

** WARNING ** : Your ApplicationContext is unlikely to start due to a @ComponentScan of the default package.

解决方案：将所有类移至通用包。

2. spring-boot-starter-thymeleaf丢失

在pom.xml文件中添加以下依赖项以使Thymeleaf模板正常工作：

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

然后删除您的中存在的以下依赖项pom.xml：

    <!-- https://mvnrepository.com/artifact/org.thymeleaf/thymeleaf -->
    <dependency>
        <groupId>org.thymeleaf</groupId>
        <artifactId>thymeleaf</artifactId>
        <version>3.0.9.RELEASE</version>
    </dependency>

3. spring.thymeleaf.mode=LEGACYHTML5需要额外的依赖

当您运行应用程序并打开http：// localhost：8080时，将看到以下异常：

org.thymeleaf.exceptions.ConfigurationException: Cannot perform conversion to XML from legacy HTML: The nekoHTML library is not in classpath. nekoHTML 1.9.15 or newer is required for processing templates in "LEGACYHTML5" mode [http://nekohtml.sourceforge.net]. Maven spec: "net.sourceforge.nekohtml::nekohtml::1.9.15". IMPORTANT: DO NOT use versions of nekoHTML older than 1.9.15.
    at org.thymeleaf.templateparser.html.AbstractHtmlTemplateParser.parseTemplate(AbstractHtmlTemplateParser.java:90) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.thymeleaf.TemplateRepository.getTemplate(TemplateRepository.java:278) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1104) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1011) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]

这是因为您指定了：

spring.thymeleaf.mode=LEGACYHTML5

并且您还没有将nekoHTML库添加到类路径。

解决方案：向您的对象添加以下依赖项pom.xml：

<dependency>
    <groupId>net.sourceforge.nekohtml</groupId>
    <artifactId>nekohtml</artifactId>
    <version>1.9.22</version>
</dependency>

应用所有这些步骤后，您将在应用程序的主页上看到“您好”。希望能帮助到你。