创建一个Vaadin请求处理程序，在Spring Security有机会之前处理请求

<dependencies>
    <!-- Vaadin -->
    <dependency>
        <groupId>com.vaadin</groupId>
        <artifactId>vaadin-spring-boot-starter</artifactId>
    </dependency>
    
    <!-- Spring Security -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>
</dependencies>

import com.vaadin.flow.server.ServiceInitEvent;
import com.vaadin.flow.server.VaadinServiceInitListener;

public class MyRequestHandler implements VaadinServiceInitListener {

    @Override
    public void serviceInit(ServiceInitEvent event) {
        // 在Spring Security之前处理请求的逻辑
        // ...
    }
}

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@ServletComponentScan
public class MyApplication implements ServletContextListener {

    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        VaadinServiceInitListener listener = new MyRequestHandler();
        VaadinService.getCurrent().addServiceInitListener(listener);
    }
}