有这样的ftlh文件和注册表：
<!DOCTYPE html>
<html lang="en">
<head>
<title>Rental Property</title>
</head>
<body>
<h2>User Registration</h2>
<form action="/registration" method="POST">
<label for="name">Name:</label>
<input type="text" id="name" name="name" value="${userForm.name!}" required>
<#if errors?? && errors?has_content && errors.hasFieldErrors("name")>
<div style="color:red;">${errors.getFieldError('name').defaultMessage}</div>
</#if>
<label for="lastName">Last Name:</label>
<input type="text" id="lastName" name="lastName" value="${userForm.lastName!}" required>
<#if errors?? && errors?has_content && errors.hasFieldErrors("lastName")>
<div style="color:red;">${errors.getFieldError("lastName").defaultMessage}</div>
</#if>
<label for="email">Email Address:</label>
<input type="email" id="email" name="email" value="${userForm.email!}" required>
<#if errors?? && errors?has_content && errors.hasFieldErrors("email")>
<div style="color:red;">${errors.getFieldError("email").defaultMessage}</div>
</#if>
<label for="phone">Phone:</label>
<input type="tel" id="phone" name="phone" value="${userForm.phone!}">
<#if errors?? && errors?has_content && errors.hasFieldErrors("phone")>
<div style="color:red;">${errors.getFieldError("phone").defaultMessage}</div>
</#if>
<label for="password">Password:</label>
<input type="password" id="password" name="password" required>
<#if errors?? && errors?has_content && errors.hasFieldErrors("password")>
<div style="color:red;">${errors.getFieldError("password").defaultMessage}</div>
</#if>
<label for="replayPassword">Repeat Password:</label>
<input type="password" id="replayPassword" name="replayPassword" required>
<#if errors?? && errors?has_content && errors.hasFieldErrors("replayPassword")>
<div style="color:red;">${errors.getFieldError("replayPassword").defaultMessage}</div>
</#if>
<label for="birthday">Date of Birth:</label>
<input type="date" id="birthday" name="birthday">
<#-- <#if errors?has_content && errors.hasFieldErrors("birthday")>-->
<#-- <div style="color:red;">${errors.getFieldError("birthday").defaultMessage}</div>-->
<#-- </#if>-->
<button type="submit">Register</button>
</form>
</body>
</html>
有这样一种post请求处理方法：
@PostMapping("/registration")
public String registration(@ModelAttribute @Valid UserForm userForm,
BindingResult result, Model model)
{
userValidator.validate(userForm, result);
model.addAttribute("errors", result);
if (result.hasErrors())
return "registration";
return "redirect:/";
}
UserForm.java 类的每个字段上方是来自 jakarta.validation.constraints 的验证注释以及自定义验证器类。 当尝试在此控制器方法内发送有错误的数据时，验证将按其应有的方式工作，查找所有错误，并在尝试向用户显示不正确的数据时发生错误：
freemarker.core.InvalidReferenceException: The following has evaluated to null or missing:
==> errors.getFieldError('name') [in template "registration.ftlh" at line 14, column 35]
----
Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----
----
FTL stack trace ("~" means nesting-related):
- Failed at: ${errors.getFieldError("name").defaul... [in template "registration.ftlh" at line 14, column 33]
----
at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134) ~[freemarker-2.3.33.jar:2.3.33]
at freemarker.core.UnexpectedTypeException.newDescriptionBuilder(UnexpectedTypeException.java:85) ~[freemarker-2.3.33.jar:2.3.33]...
我尝试将 ftlh 文件中的错误键更改为单引号，更改验证，发送整个组装的 UserForm 对象。
我怀疑问题是您没有启用公开 Java 8 默认方法。它是必需的，因为 FreeMarker 基于
java.beans.Introspector添加了解决方法（默认情况下未启用）以将 Java 8 默认方法（以及它们定义的 bean 属性）公开给模板，尽管
（官方 JavaBeans 内省器）会忽略它们，至少从 JRE 1.8.0_66 开始是这样。要启用此解决方法，请将java.beans.Introspector或incompatibleImprovements的DefaultObjectWrapper构造函数参数的值增加到 2.3.26，或者将其BeansWrapper设置设置为 true。请注意，如果您将treatDefaultMethodsAsBeanMembers的object_wrapper设置保留为默认值，则将Configuration的incompatibleImprovements设置增加到 2.3.26 就足够了，因为它是由默认Configuration继承的。object_wrapper
我的建议是增加
incompatibleImprovementsConfiguration