使用手册示例代码在Vaadin流中编写'UI'子类

在手册的第页 Differences Between V10 and V8 Applications ,这里有一个示例代码,供那些想编写 UI Vaadin Flow .

(将原始mydomain.com更改为 example.com

@WebServlet(urlPatterns = "/*", name = "myservlet", asyncSupported = true,
// Example on initialization parameter configuration
initParams = {
        @WebInitParam(name = "frontend.url.es6", value = "http://example.com/es6/"),
        @WebInitParam(name = "frontend.url.es5", value = "http://example.com/es5/") })
// The UI configuration is optional
@VaadinServletConfiguration(ui = MyUI.class, productionMode = false)
public class MyServlet extends VaadinServlet {
}

// this is not necessary anymore, but might help you get started with migration
public class MyUI extends UI {
    protected void init(VaadinRequest request) {
        // do initial steps here.
        // previously routing
    }
}   

从语法上说,这要么是不正确的,要么是要写进两个单独的文本中 .java 文件夹。

还是应该 MyServlet 必须在 MyUI 类,就像在Vaadin 8中默认做的那样?这样地:

package com.raddkit;

import com.vaadin.flow.component.UI;
import com.vaadin.flow.server.VaadinRequest;
import com.vaadin.flow.server.VaadinServlet;
import com.vaadin.flow.server.VaadinServletConfiguration;

import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;

public class MyUI extends UI {
    protected void init ( VaadinRequest request ) {

    }

    @WebServlet ( urlPatterns = "/*", name = "myservlet", asyncSupported = true,
        // Example on initialization parameter configuration
        initParams = {
            @WebInitParam ( name = "frontend.url.es6", value = "http://example.com/es6/" ) ,
            @WebInitParam ( name = "frontend.url.es5", value = "http://example.com/es5/" ) } )
    // The UI configuration is optional
    @VaadinServletConfiguration ( ui = MyUI.class, productionMode = false )
    public class MyServlet extends VaadinServlet {
    }
}