小编Dou*_*uma的帖子

我正在尝试创建一个仪表板应用程序，其中多个小部件通过 SSE 获取更新。我的 DashboardController 看起来像：

public class DashboardController
{
    private WidgetService widgetService;

    public DashboardController(WidgetService widgetService)
    {
        this.widgetService = widgetService;
    }

    @GetMapping("/")
    public String index(final Model model)
    {
        for(WidgetInterface<?> widget : widgetService.getAll()) {
            model.addAttribute("widget-data-driver-" + widget.getIdentifier(),
                    new ReactiveDataDriverContextVariable(widget.getInitialData(), 100));
        }
        model.addAttribute("widgets", widgetService.getAll());
        return "index";
    }
}

和我的小部件界面：

public interface WidgetInterface<T>
{
    public String getIdentifier();
    public String getTitle();
    public String getStreamEndpoint();
    public Flux<T> getInitialData();
    public Map<String, String> getColumns();
    public String getThymeLeafFraction();
    public Date getLastItemDate();
    public Flux<T> getItemsUpdatedSince(Date date);
}

一个小部件（来自 WidgetService）一切正常。我正在尝试将ReactiveDataDriverContextVariable …

为了在 Symfony 3 中设置 Sonata 管理员，我遵循了确切的说明： https://symfony.com/doc/3.x/bundles/SonataAdminBundle/getting_started/creating_an_admin.html

在步骤 3 中，我已输入所述的确切配置： https://symfony.com/doc/3.x/bundles/SonataAdminBundle/getting_started/creating_an_admin.html#step-3-register-the-admin-class

services:
    # ...
    admin.category:
        class: App\Admin\CategoryAdmin
        arguments: [~, App\Entity\Category, ~]
        tags:
            - { name: sonata.admin, manager_type: orm, label: Category }

但现在我收到以下错误：

The service "admin.category" has a dependency on a non-existent service "sonata.admin.manager.orm".  

我很难理解为什么以下代码不是异常的子类，但为什么会编译：

class Test 
{
    public void run() throws IOException 
    {
        System.out.println("Test");
    }
}

class SubTest extends Test 
{
    //not a subclass of IOException, still compiles 
    public void run() throws RuntimeException 
    {
        System.out.println("Test from sub");
    }
}

class Sub2Test extends Test 
{
    //not a subclass of IOException, does not compile
    public void run() throws Exception  
    {
        System.out.println("Test from sub");
    }
}

我知道这RuntimeException是一个未经检查的异常，但是我认为规则是它必须是父异常的子类？

我有一个非常简单的 Hibernate 设置，但是在保存实体时收到这个奇怪的错误：

org.hibernate.property.access.spi.PropertyAccessException：通过持久属性 [com.example.demo.Student#firstName] 的反射访问字段 [private java.lang.String com.example.demo.Student.firstName] 时出错：Student [id=0，名字=我的，姓氏=姓名]

这就是我保存它的方式：

StudentDao studentDao = new StudentDao();
Student student = new Student("My", "Name");
studentDao.saveStudent(student);

这是我的学生实体：

package com.example.demo;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "student")
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private int id;
    @Column(name = "first_name")
    private String firstName;
    @Column(name = "last_name")
    private String lastName;
    public Student() {
    }
    public Student(String firstName, String lastName) {
        this.firstName …