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我正在开发一个 ADF Fusion Web 应用程序，其中包含一个带有 JDeveloper 11.1.1.4.0 的消息传递模块。我搜索了进行服务器端推送的技术（也问了一个关于它的问题）我搜索了“彗星”、服务器端推送等。我找到了Active Data Service和一些聊天或服务器端推送示例：

我按照biemond 博客中的说明进行 ADS 的配置

将 ads conf 添加到 ADF META-INF/services 文件夹下的 adf-config.xml

<ads:adf-activedata-config xmlns="http://xmlns.oracle.com/adf/activedata/config">
    <transport>long-polling</transport>  
    <latency-threshold>10000</latency-threshold>  
    <keep-alive-interval>10000</keep-alive-interval>  
    <polling-interval>3000</polling-interval>  
    <max-reconnect-attempt-time>1800000</max-reconnect-attempt-time>  
    <reconnect-wait-time>10000</reconnect-wait-time></ads:adf-activedata-config>

并创建了 adf-config.properties 文件

http\://xmlns.oracle.com/adf/activedata/config=oracle.adfinternal.view.faces.activedata.ActiveDataConfiguration$ActiveDataConfigCallback

并在 jsf 页面中创建了一个表。

<af:table value="#{MessageModel}" var="row"
                rows="#{bindings.MessageVO.rangeSize}"
                emptyText="#{bindings.MessageVO.viewable ? 'No data to display.' : 'Access Denied.'}"
                fetchSize="#{bindings.MessageVO.rangeSize}"
                rowBandingInterval="0" id="t1">
        <af:column sortProperty="id" sortable="false"
                   headerText="#{bindings.MessageVO.hints.id.label}"
                   id="c1">
          <af:outputText value="#{row.id}" id="ot2">
            <af:convertNumber groupingUsed="false"
                              pattern="#{bindings.MessageVO.hints.id.format}"/>
          </af:outputText>
        </af:column>
        <af:column sortProperty="Title" sortable="false"
                   headerText="#{bindings.MessageVO.hints.Title.label}"
                   id="c2">
          <af:outputText value="#{row.title}" id="ot3"/>
        </af:column>
      </af:table>

并创建了 MessageModel 类，该类用作 jsff 中的表值。

public class MessageModel extends ActiveCollectionModelDecorator {  

 private MessageActiveDataModel activeDataModel = new MessageActiveDataModel();  
 private CollectionModel model = null;  


 public CollectionModel getCollectionModel() {
    if (model == null) {
        DCBindingContainer dcBindings = (DCBindingContainer)BindingContext.getCurrent().getCurrentBindingsEntry();  
        FacesCtrlHierBinding treeData = (FacesCtrlHierBinding)dcBindings.getControlBinding("MessageVO");  
        model = treeData.getCollectionModel();  
    }
    return model;
 }

 public MessageActiveDataModel getActiveDataModel() {
      return activeDataModel;
 }

 public MessageActiveDataModel getMessageActiveDataModel() {  
     return activeDataModel;  
 }  

}

和一个 ActiveDataModel 类

public class MessageActiveDataModel extends BaseActiveDataModel {

private final AtomicInteger listenerCount = new AtomicInteger(0);
private final AtomicInteger currEventId = new AtomicInteger();

protected void startActiveData(Collection<Object> rowKeys,
                               int startChangeCount) {
    listenerCount.incrementAndGet();
    if (listenerCount.get() == 1) {
        System.out.println("start up");

        Runnable dataChanger = new Runnable() {
            public void run() {
                System.out.println("MyThread starting.");
                try {
                    Thread.sleep(2000);
                    System.out.println("thread running");
                    Change chg = new Change();
                    chg.triggerDataChange(MessageActiveDataModel.this);
                } catch (Exception exc) {
                    System.out.println("MyThread exceptioned out.");
                }
                System.out.println("MyThread terminating.");
            }
        };
        Thread newThrd = new Thread(dataChanger);
        newThrd.start();
    }
}

protected void stopActiveData(Collection<Object> rowKeys) {
    listenerCount.decrementAndGet();
    if (listenerCount.get() == 0) {
        System.out.println("tear down");
    }
}

public int getCurrentChangeCount() {
    return currEventId.get();
}

public void bumpChangeCount() {
    currEventId.incrementAndGet();
}

public void dataChanged(ActiveDataUpdateEvent event) {
    fireActiveDataUpdate(event);
}

}

ActiveDataModel 类中的线程触发了一个名为 Change 的类

public class Change {
public Change() {
}

public void triggerDataChange(MessageActiveDataModel model) throws Exception {
    for (int i = 0; i < 10; i++) {
        try {
            Thread.sleep(4000);
        } catch (InterruptedException ie) {
            ie.printStackTrace();
        }
        model.bumpChangeCount();
        ActiveDataUpdateEvent event =
            ActiveDataEventUtil.buildActiveDataUpdateEvent(ActiveDataEntry.ChangeType.UPDATE,
                                                           model.getCurrentChangeCount(),
                                                           JboActiveDataEventUtil.convertKeyPath(new Object[] { new Long(1),
                                                                                                                new Integer(0) }),
                                                           null,
                                                           new String[] { "title" },
                                                           new Object[] { "Administration" });

        model.dataChanged(event);
    }
}

}

当我运行应用程序时，我可以在表中看到 MessageVO 中的行。它进入模型类、活动数据模型类和更改类，更改 ActiveDataMode 类中的 listenerCount 和 currentEventId 值。当我更新数据库中的行时，它不会触发更改事件，也不会检测数据库中的更新。

有没有人知道如何监听数据库的变化并根据 ADF 中的数据库变化进行服务器端推送？

提前致谢。

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