Spring Boot下如何从Thymeleaf调用@Service bean

Question

我有一个被定义为服务的 bean：

@Service
public class FileHandling {
  public void doSomething() {
...

可以在我的应用程序中自动装配它并使用它：

@Autowired
@Qualifier("fileHandling")
FileHandling fh;

当我尝试在 Thymeleaf 模板中使用它时，我收到以下错误消息：

org.springframework.expression.spel.SpelEvaluationException：EL1057E：上下文中没有注册任何 bean 解析器来解析对 bean 'fileHandling' 的访问

这是我的模板的相关部分：

<td th:text="${@fileHandling.doSomething()}">...</td>  

这是我访问模板引擎的方式：

final Context ctx = new Context();
ctx.setVariable("files", map);
ctx.setVariable("fileHandling",fh);

String html = templateEngine.process("flattopic", ctx);

I receive the error message no matter if I try to access the bean directly or after setVariable("fileHandling"). The syntax I use complies to what I see in chapter 5 of https://www.thymeleaf.org/doc/articles/springmvcaccessdata.html.

I've seen similar questions which apply to basic SPEL (this one) or an unanswered question specific to Thymeleaf. The alternative to switch from a bean to a static class and use ${T(org.foo.bar.package.FileHandling).doSomething()} is something that I would like to avoid.

How can I solve this or make the bean accessible ?

Answer 1

“在Spring Boot下从Thymeleaf调用bean”也是“在Spring MVC下从Thymeleaf调用bean”。例如：

界面

package com.example;

public interface UrlService {

    String getApplicationUrl();

}

你有组件MyConfiguration

package com.example;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MyConfiguration {

    @Bean(name = "urlService")
    public UrlService urlService() {
        return () -> "domain.com/myapp";
    }

}

在 Thymeleaf 模板文件中foo.html

<div th:text="${@urlService.getApplicationUrl()}">...</div>

资料来源：https ://www.thymeleaf.org/doc/articles/springmvcaccessdata.html#spring-beans