Question

我为Spring Boot应用程序创建了一个带有<input type="date" ...>的简单表单。我希望在控制器中将其转换为LocalDate。我收到错误消息：

Fri Aug 17 15:32:01 CEST 2018
There was an unexpected error (type=Internal Server Error, status=500).
No primary or default constructor found for class java.time.LocalDate

这当然是正确的，但是-就我所知-没关系，因为根据文档：“ [...] @DateTimeFormat批注应与Java上的java.time一起使用8和春季4。”

控制器方法：

@PostMapping("/users")
public String register(String user, String pw, @DateTimeFormat(iso=DateTimeFormat.ISO.DATE) LocalDate beginning){

    MyUser myUser = MyUser.create(user,pw);
    MyUser.setEnabled(beginning);

    repo.register(myUser);

    return "redirect:/users/"+user;
}

html / thymeleaf：

<form method="POST">
<div><label> Benutzername : <input type="text" name="user"/> </label></div>
<div><label> Passwort: <input type="password" name="password"/> </label></div>
<div><label> Freigeschaltet ab (optional): <input type="date" name="beginning"/> </label></div>
<div><input type="submit" value="Registrieren"/></div>
</form>

pom（节选）

 <dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>2.0.4.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <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>
...
</dependencies>   

<properties>
    <java.version>1.8</java.version>
</properties>

编辑：完整的html

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"
  xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
<head>
<title>Users</title>
</head>
<body>

<div th:insert="fragments :: logoutButton">...</div>

<div class ="user_list">
<h2>Registrierte Nutzer</h2>

<div>
<table border="1">
    <tr>
        <td>Name</td>
        <td>Freigeschaltet ab</td>
        <td>Freigeschaltet bis</td>
        <td>Passwort gesetzt</td>
        <td>Freigaben</td>
    </tr>
    <tr th:each="user : ${users}">
        <td th:text="${user.userName}"/>
        <td th:text="${user.enabled}"/>
        <td th:text="${user.disabled}"/>
        <td th:text="${user.pwSet}"/>
        <td th:text="${user.authorities}"/>
    </tr>
</table>
</div>
</div>

<div class ="register_user">
<h2>Neuen Benutzer Registrieren</h2>

<form method="POST">
<div><label> Benutzername : <input type="text" name="user"/> </label>    </div>
<div><label> Password: <input type="password" name="password"/> </label></div>
<div><label> Freigeschaltet ab (optional): <input type="date" name="beginning"/> </label></div>
<div><input type="submit" value="Registrieren"/></div>
</form>
</div>
</body>
</html>

Answer 1

LocaDate不提供自己的构造函数，而是使用静态方法调用实例化的。

此问题已在SPR-13362中解决，并且可以正常工作。解决方法是使用@ModelAttribute批注创建模型属性，并将其传递给请求：

@ModelAttribute
LocalDate initLocalDate() {
    return LocalDate.now();
}

然后将其传递给请求：

@PostMapping("/users")
public String register(
    String user, 
    String pw,  
    @DateTimeFormat(iso=DateTimeFormat.ISO.DATE)  @ModelAttribute LocalDate beginning) 
{
    // ...
}

Spring Boot + LocalDate：“没有主要或默认构造函数”

1 个答案: