Question

我是Vaadin的新手，只是实现了一个用于测试功能的Prototype。目前我正在使用Vaadin Server-Push功能。我喜欢做一个简单的计数器，可以通过Button增加。之后我喜欢从不同的浏览器打开这一面，当我计算时，我喜欢所有浏览器都要更新。

现在我已经知道当前的浏览器是由一个单独的线程更新的。

public class PushTestView extends VerticalLayout implements View {

   private static final long serialVersionUID = -8056849522760207972L;
   private Label counter;

   public void enter(ViewChangeEvent event) {
      removeAllComponents();
      PushTestController controller = PushTestController.getInstance();
      counter = new Label("" + controller.getCounter());
      Button button = new Button("Count up");

      button.addClickListener(new ClickListener() {
         private static final long serialVersionUID = -1437136914245802675L;

         @Override
         public void buttonClick(ClickEvent event) {
            InitializerThread thread = new InitializerThread();
            thread.run();
         }
      });

      addComponent(counter);
      addComponent(button);

   }

   class InitializerThread extends Thread {
      @Override
      public void run() {
         // Init done, update the UI after doing locking
         UI.getCurrent().access(new Runnable() {
            @Override
            public void run() {
               // Here the UI is locked and can be updated
               PushTestController.getInstance().countUp();
               counter.setValue("" + PushTestController.getInstance().getCounter());
               UI.getCurrent().notifyAll();
            }
         });
      }
   }
}

我嵌入到我的UI中的这个视图由@Push注释。这是我的控制器：

public class PushTestController {

   private static PushTestController instance = new PushTestController();
   private int counter = 0;

   private PushTestController() {
      //Private Constructor for Singleton 
   }

   public static PushTestController getInstance() {
      return instance;
   }

   public int getCounter() {
      return counter;
   }

   public String getCounterString() {
      return "" + counter;
   }

   public void countUp() {
      counter++;
   }
}

如何扩展此示例以便在不同浏览器中更新UI？

Answer 1

看看这个，第11.16.3节：https://vaadin.com/book/vaadin7/-/page/advanced.push.html

Answer 2

您必须在项目中使用servlet 3.0并编辑ivy.xml（或者如果您使用Maven然后使用pom.xml）。之后，您必须添加@Push注释以启用ui的推送。像这样：

<dependency org="com.vaadin" name="vaadin-push" rev="&vaadin.version;" conf="default->default" />

在Maven中

：

<dependency>
  <groupId>com.vaadin</groupId>
  <artifactId>vaadin-push</artifactId>
  <version>${vaadin.version}</version>
</dependency>

servlet配置：

<servlet>
    <servlet-name>MyServlet</servlet-name>
    <servlet-class>com.vaadin.server.VaadinServlet</servlet-class>
    <init-param>
        <param-name>ui</param-name>
        <param-value>org.vaadin.example.MyUI</param-value>
    </init-param>
    <async-supported>true</async-supported>
</servlet>

最后是@Push

@Push 
public class PushTestUI extends UI

Reference here

Vaadin 7.1.0推

2 个答案: