Java tutorial
/************************************************************************************** * Copyright (C) 2006-2015 EsperTech Inc. All rights reserved. * * http://www.espertech.com/esper * * http://www.espertech.com * * ---------------------------------------------------------------------------------- * * The software in this package is published under the terms of the GPL license * * a copy of which has been included with this distribution in the license.txt file. * **************************************************************************************/ package com.espertech.esper.view.std; import com.espertech.esper.client.EventBean; import com.espertech.esper.client.EventType; import com.espertech.esper.collection.MultiKeyUntyped; import com.espertech.esper.collection.OneEventCollection; import com.espertech.esper.core.context.util.AgentInstanceViewFactoryChainContext; import com.espertech.esper.event.EventAdapterService; import com.espertech.esper.view.*; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import java.util.*; /** * This view simply adds a property to the events posted to it. This is useful for the group-merge views. */ public final class AddPropertyValueOptionalView extends ViewSupport implements CloneableView, StoppableView { private final AgentInstanceViewFactoryChainContext agentInstanceContext; private final String[] propertyNames; private final Object propertyValues; private final EventType eventType; private boolean mustAddProperty; // Keep a history of posted old events to avoid reconstructing the event // and adhere to the contract of posting the same reference to child views. // Only for must-add-property. private Map<EventBean, EventBean> newToOldEventMap; /** * Constructor. * @param propertyNames is the name of the field that is added to any events received by this view. * @param mergeValues is the values of the field that is added to any events received by this view. * @param mergedResultEventType is the event type that the merge view reports to it's child views * @param agentInstanceContext contains required view services */ public AddPropertyValueOptionalView(AgentInstanceViewFactoryChainContext agentInstanceContext, String[] propertyNames, Object mergeValues, EventType mergedResultEventType) { this.propertyNames = propertyNames; this.propertyValues = mergeValues; this.eventType = mergedResultEventType; this.agentInstanceContext = agentInstanceContext; this.newToOldEventMap = Collections.emptyMap(); } public View cloneView() { return new AddPropertyValueOptionalView(agentInstanceContext, propertyNames, propertyValues, eventType); } public void setParent(Viewable parent) { if (log.isDebugEnabled()) { log.debug(".setParent parent=" + parent); } super.setParent(parent); if (parent.getEventType() != eventType) { mustAddProperty = true; newToOldEventMap = new HashMap<EventBean, EventBean>(); } else { mustAddProperty = false; } } /** * Returns field name for which to set the merge value for. * @return field name to use to set value */ public final String[] getPropertyNames() { return propertyNames; } /** * Returns the value to set for the field. * @return value to set */ public final Object getPropertyValues() { return propertyValues; } public final void update(EventBean[] newData, EventBean[] oldData) { if (!mustAddProperty) { updateChildren(newData, oldData); return; } EventBean[] newEvents = null; EventBean[] oldEvents = null; if (newData != null) { newEvents = new EventBean[newData.length]; int index = 0; for (EventBean newEvent : newData) { EventBean theEvent = addProperty(newEvent, propertyNames, propertyValues, eventType, agentInstanceContext.getStatementContext().getEventAdapterService()); newEvents[index++] = theEvent; newToOldEventMap.put(newEvent, theEvent); } } if (oldData != null) { oldEvents = new EventBean[oldData.length]; int index = 0; for (EventBean oldEvent : oldData) { EventBean outgoing = newToOldEventMap.remove(oldEvent); if (outgoing != null) { oldEvents[index++] = outgoing; } else { EventBean theEvent = addProperty(oldEvent, propertyNames, propertyValues, eventType, agentInstanceContext.getStatementContext().getEventAdapterService()); oldEvents[index++] = theEvent; } } } updateChildren(newEvents, oldEvents); } public final EventType getEventType() { return eventType; } public final Iterator<EventBean> iterator() { final Iterator<EventBean> parentIterator = parent.iterator(); return new Iterator<EventBean>() { public boolean hasNext() { return parentIterator.hasNext(); } public EventBean next() { EventBean nextEvent = parentIterator.next(); if (mustAddProperty) { return addProperty(nextEvent, propertyNames, propertyValues, eventType, agentInstanceContext.getStatementContext().getEventAdapterService()); } else { return nextEvent; } } public void remove() { throw new UnsupportedOperationException(); } }; } @Override public void stop() { if (!newToOldEventMap.isEmpty()) { OneEventCollection oldEvents = new OneEventCollection(); for (Map.Entry<EventBean, EventBean> oldEvent : newToOldEventMap.entrySet()) { oldEvents.add(oldEvent.getValue()); } if (!oldEvents.isEmpty()) { updateChildren(null, oldEvents.toArray()); } newToOldEventMap.clear(); } } /** * Add a property to the event passed in. * @param originalEvent - event to add property to * @param propertyNames - names of properties to add * @param propertyValues - value of properties to add * @param targetEventType - new event type * @param eventAdapterService - service for generating events and handling event types * @return event with added property */ protected static EventBean addProperty(EventBean originalEvent, String[] propertyNames, Object propertyValues, EventType targetEventType, EventAdapterService eventAdapterService) { Map<String, Object> values = new HashMap<String, Object>(); if (propertyValues instanceof MultiKeyUntyped) { MultiKeyUntyped props = (MultiKeyUntyped) propertyValues; Object[] propertyValuesArr = props.getKeys(); for (int i = 0; i < propertyNames.length; i++) { values.put(propertyNames[i], propertyValuesArr[i]); } } else { values.put(propertyNames[0], propertyValues); } return eventAdapterService.adapterForTypedWrapper(originalEvent, values, targetEventType); } public final String toString() { return this.getClass().getName() + " propertyNames=" + Arrays.toString(propertyNames) + " propertyValue=" + propertyValues; } private static final Log log = LogFactory.getLog(AddPropertyValueOptionalView.class); }