Question

我正在尝试创建注册页面。该网站非常简单，主页将返回注册页面，单击“提交”后，应将其保存到数据库中。但是我在获取页面时遇到了麻烦。

Applicant.java

    import javax.persistence.*;
    import javax.validation.constraints.NotBlank;
    import java.util.Date;

    @Entity
    @Table(name = "bayilik_basvuru")
    public class Applicant {
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private int id;
        @NotBlank(message = "İsim Soyisim Girilmelidir.")
        @Column(name = "isim_soyisim")
        private String adSoyad;

        public Applicant() {

        }

        public String getAdSoyad() {
            return adSoyad;
        }

        public void setAdSoyad(String adSoyad) {
            this.adSoyad = adSoyad;
        }

    }

控制器

@Controller
public class HomeContoller {

    @Autowired
    private ApplicantDAO dao;

    @RequestMapping("/")
    public ModelAndView getApplicationPage(){
        ModelAndView model = new ModelAndView();
        Applicant applicant = new Applicant();
        model.addObject("applicant",applicant);
        model.setViewName("index");

        return model;
    }


    @PostMapping("/save")
    public String saveApplicant(@Valid Applicant applicant, BindingResult result){
        if (result.hasErrors()) {
            return "add-student";
        }

        dao.save(applicant);
        return "index";
    }
}

Index.html->表单的一部分，

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Bayilik Ön Başvuru Formu</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">    <link rel="stylesheet" type="text/css" th:href="@{../css/style.css}" />
    <link rel="stylesheet" type="text/css" th:href="@{../css/bootstrap-datetimepicker.min.css}" />
    <link rel="stylesheet" type="text/css" th:href="@{../css/roboto-font.css}" />

    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
</head>
<body>
<form class="form-horizantal" th:action="@{/save}" th:object="${applicant}"
                                  method="POST">
        <div class="form-group">
        <label class="col-md-4 control-label">İsim Soyisim</label>
        <div class="col-md-8">
           <input type="text" th:field="*{adSoyad}" class="form-control" /> <!-- it gives error at this line at the start of the th:field-->
           <span th:if="${#fields.hasErrors('adSoyad')}" th:errors="*{adSoyad}" class="text-danger"></span>
        </div>
</div>
</body>
</html>

我已经处理了好几个小时了。我已经将其与许多示例进行了比较，并且html文件看起来不错，控制器看起来不错，我不知道我在做什么错。

在我的pom文件中，我有百里香；

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

顺便说一句是这个错误

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.

Thu Oct 31 01:40:47 EET 2019
There was an unexpected error (type=Internal Server Error, status=500).
Error during execution of processor 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "index" - line 27, col 56) // this line is the same line I showed on the index.html file

Answer 1

您没有在/ save端点上使用注释@ModelAttribute。尝试像这样使用它：

@PostMapping("/save")
public String saveApplicant( @Valid @ModelAttribute("applicant") Applicant applicant, BindingResult result){
    if (result.hasErrors()) {
        return "add-student";
    }

    dao.save(applicant);
    return "index";
}

在您的百里香叶模板th:object="${applicant}"中，表达式声明了用于收集表单数据的模型对象。因此，在控制器中，您必须使用批注@ModelAttribute将申请人对象绑定到传入的表单内容。

Answer 2

更改get方法以正确添加对象：

<?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>multithreadedCalls</groupId>
    <artifactId>multithreadedCalls</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.10</version>
        </dependency>
    </dependencies>
</project>

查看Lombok项目可大大简化您的bean。您缺少@GetMapping("/") //simpler, more informative public String getApplicationPage(Model model){ model.addAttribute("applicant", new Applicant()); //note method name return "index"; }属性的getter和setter，并且在类上标注id和@Getter会删除很多样板。

您还希望在post方法上为@Setter参数添加@ModelAttribute注释。

将来，也请发布您的完整堆栈跟踪。

Answer 3

项目上似乎存在层次结构问题。在修复文件层次结构之后，代码开始工作。

感谢答复者的尝试，但是他们不知道问题的核心，因为我没有在问题上附加层次结构的屏幕截图。

HTML页面未在Springboot应用程序上显示

3 个答案: